1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * kernel/workqueue.c - generic async execution with shared worker pool 4 * 5 * Copyright (C) 2002 Ingo Molnar 6 * 7 * Derived from the taskqueue/keventd code by: 8 * David Woodhouse <dwmw2@infradead.org> 9 * Andrew Morton 10 * Kai Petzke <wpp@marie.physik.tu-berlin.de> 11 * Theodore Ts'o <tytso@mit.edu> 12 * 13 * Made to use alloc_percpu by Christoph Lameter. 14 * 15 * Copyright (C) 2010 SUSE Linux Products GmbH 16 * Copyright (C) 2010 Tejun Heo <tj@kernel.org> 17 * 18 * This is the generic async execution mechanism. Work items as are 19 * executed in process context. The worker pool is shared and 20 * automatically managed. There are two worker pools for each CPU (one for 21 * normal work items and the other for high priority ones) and some extra 22 * pools for workqueues which are not bound to any specific CPU - the 23 * number of these backing pools is dynamic. 24 * 25 * Please read Documentation/core-api/workqueue.rst for details. 26 */ 27 28 #include <linux/export.h> 29 #include <linux/kernel.h> 30 #include <linux/sched.h> 31 #include <linux/init.h> 32 #include <linux/interrupt.h> 33 #include <linux/signal.h> 34 #include <linux/completion.h> 35 #include <linux/workqueue.h> 36 #include <linux/slab.h> 37 #include <linux/cpu.h> 38 #include <linux/notifier.h> 39 #include <linux/kthread.h> 40 #include <linux/hardirq.h> 41 #include <linux/mempolicy.h> 42 #include <linux/freezer.h> 43 #include <linux/debug_locks.h> 44 #include <linux/lockdep.h> 45 #include <linux/idr.h> 46 #include <linux/jhash.h> 47 #include <linux/hashtable.h> 48 #include <linux/rculist.h> 49 #include <linux/nodemask.h> 50 #include <linux/moduleparam.h> 51 #include <linux/uaccess.h> 52 #include <linux/sched/isolation.h> 53 #include <linux/sched/debug.h> 54 #include <linux/nmi.h> 55 #include <linux/kvm_para.h> 56 #include <linux/delay.h> 57 #include <linux/irq_work.h> 58 59 #include "workqueue_internal.h" 60 61 enum worker_pool_flags { 62 /* 63 * worker_pool flags 64 * 65 * A bound pool is either associated or disassociated with its CPU. 66 * While associated (!DISASSOCIATED), all workers are bound to the 67 * CPU and none has %WORKER_UNBOUND set and concurrency management 68 * is in effect. 69 * 70 * While DISASSOCIATED, the cpu may be offline and all workers have 71 * %WORKER_UNBOUND set and concurrency management disabled, and may 72 * be executing on any CPU. The pool behaves as an unbound one. 73 * 74 * Note that DISASSOCIATED should be flipped only while holding 75 * wq_pool_attach_mutex to avoid changing binding state while 76 * worker_attach_to_pool() is in progress. 77 * 78 * As there can only be one concurrent BH execution context per CPU, a 79 * BH pool is per-CPU and always DISASSOCIATED. 80 */ 81 POOL_BH = 1 << 0, /* is a BH pool */ 82 POOL_MANAGER_ACTIVE = 1 << 1, /* being managed */ 83 POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ 84 POOL_BH_DRAINING = 1 << 3, /* draining after CPU offline */ 85 }; 86 87 enum worker_flags { 88 /* worker flags */ 89 WORKER_DIE = 1 << 1, /* die die die */ 90 WORKER_IDLE = 1 << 2, /* is idle */ 91 WORKER_PREP = 1 << 3, /* preparing to run works */ 92 WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ 93 WORKER_UNBOUND = 1 << 7, /* worker is unbound */ 94 WORKER_REBOUND = 1 << 8, /* worker was rebound */ 95 96 WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE | 97 WORKER_UNBOUND | WORKER_REBOUND, 98 }; 99 100 enum work_cancel_flags { 101 WORK_CANCEL_DELAYED = 1 << 0, /* canceling a delayed_work */ 102 WORK_CANCEL_DISABLE = 1 << 1, /* canceling to disable */ 103 }; 104 105 enum wq_internal_consts { 106 NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */ 107 108 UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */ 109 BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ 110 111 MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ 112 IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ 113 114 MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2, 115 /* call for help after 10ms 116 (min two ticks) */ 117 MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ 118 CREATE_COOLDOWN = HZ, /* time to breath after fail */ 119 120 /* 121 * Rescue workers are used only on emergencies and shared by 122 * all cpus. Give MIN_NICE. 123 */ 124 RESCUER_NICE_LEVEL = MIN_NICE, 125 HIGHPRI_NICE_LEVEL = MIN_NICE, 126 127 WQ_NAME_LEN = 32, 128 WORKER_ID_LEN = 10 + WQ_NAME_LEN, /* "kworker/R-" + WQ_NAME_LEN */ 129 }; 130 131 /* 132 * We don't want to trap softirq for too long. See MAX_SOFTIRQ_TIME and 133 * MAX_SOFTIRQ_RESTART in kernel/softirq.c. These are macros because 134 * msecs_to_jiffies() can't be an initializer. 135 */ 136 #define BH_WORKER_JIFFIES msecs_to_jiffies(2) 137 #define BH_WORKER_RESTARTS 10 138 139 /* 140 * Structure fields follow one of the following exclusion rules. 141 * 142 * I: Modifiable by initialization/destruction paths and read-only for 143 * everyone else. 144 * 145 * P: Preemption protected. Disabling preemption is enough and should 146 * only be modified and accessed from the local cpu. 147 * 148 * L: pool->lock protected. Access with pool->lock held. 149 * 150 * LN: pool->lock and wq_node_nr_active->lock protected for writes. Either for 151 * reads. 152 * 153 * K: Only modified by worker while holding pool->lock. Can be safely read by 154 * self, while holding pool->lock or from IRQ context if %current is the 155 * kworker. 156 * 157 * S: Only modified by worker self. 158 * 159 * A: wq_pool_attach_mutex protected. 160 * 161 * PL: wq_pool_mutex protected. 162 * 163 * PR: wq_pool_mutex protected for writes. RCU protected for reads. 164 * 165 * PW: wq_pool_mutex and wq->mutex protected for writes. Either for reads. 166 * 167 * PWR: wq_pool_mutex and wq->mutex protected for writes. Either or 168 * RCU for reads. 169 * 170 * WQ: wq->mutex protected. 171 * 172 * WR: wq->mutex protected for writes. RCU protected for reads. 173 * 174 * WO: wq->mutex protected for writes. Updated with WRITE_ONCE() and can be read 175 * with READ_ONCE() without locking. 176 * 177 * MD: wq_mayday_lock protected. 178 * 179 * WD: Used internally by the watchdog. 180 */ 181 182 /* struct worker is defined in workqueue_internal.h */ 183 184 struct worker_pool { 185 raw_spinlock_t lock; /* the pool lock */ 186 int cpu; /* I: the associated cpu */ 187 int node; /* I: the associated node ID */ 188 int id; /* I: pool ID */ 189 unsigned int flags; /* L: flags */ 190 191 unsigned long watchdog_ts; /* L: watchdog timestamp */ 192 bool cpu_stall; /* WD: stalled cpu bound pool */ 193 194 /* 195 * The counter is incremented in a process context on the associated CPU 196 * w/ preemption disabled, and decremented or reset in the same context 197 * but w/ pool->lock held. The readers grab pool->lock and are 198 * guaranteed to see if the counter reached zero. 199 */ 200 int nr_running; 201 202 struct list_head worklist; /* L: list of pending works */ 203 204 int nr_workers; /* L: total number of workers */ 205 int nr_idle; /* L: currently idle workers */ 206 207 struct list_head idle_list; /* L: list of idle workers */ 208 struct timer_list idle_timer; /* L: worker idle timeout */ 209 struct work_struct idle_cull_work; /* L: worker idle cleanup */ 210 211 struct timer_list mayday_timer; /* L: SOS timer for workers */ 212 213 /* a workers is either on busy_hash or idle_list, or the manager */ 214 DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER); 215 /* L: hash of busy workers */ 216 217 struct worker *manager; /* L: purely informational */ 218 struct list_head workers; /* A: attached workers */ 219 220 struct ida worker_ida; /* worker IDs for task name */ 221 222 struct workqueue_attrs *attrs; /* I: worker attributes */ 223 struct hlist_node hash_node; /* PL: unbound_pool_hash node */ 224 int refcnt; /* PL: refcnt for unbound pools */ 225 226 /* 227 * Destruction of pool is RCU protected to allow dereferences 228 * from get_work_pool(). 229 */ 230 struct rcu_head rcu; 231 }; 232 233 /* 234 * Per-pool_workqueue statistics. These can be monitored using 235 * tools/workqueue/wq_monitor.py. 236 */ 237 enum pool_workqueue_stats { 238 PWQ_STAT_STARTED, /* work items started execution */ 239 PWQ_STAT_COMPLETED, /* work items completed execution */ 240 PWQ_STAT_CPU_TIME, /* total CPU time consumed */ 241 PWQ_STAT_CPU_INTENSIVE, /* wq_cpu_intensive_thresh_us violations */ 242 PWQ_STAT_CM_WAKEUP, /* concurrency-management worker wakeups */ 243 PWQ_STAT_REPATRIATED, /* unbound workers brought back into scope */ 244 PWQ_STAT_MAYDAY, /* maydays to rescuer */ 245 PWQ_STAT_RESCUED, /* linked work items executed by rescuer */ 246 247 PWQ_NR_STATS, 248 }; 249 250 /* 251 * The per-pool workqueue. While queued, bits below WORK_PWQ_SHIFT 252 * of work_struct->data are used for flags and the remaining high bits 253 * point to the pwq; thus, pwqs need to be aligned at two's power of the 254 * number of flag bits. 255 */ 256 struct pool_workqueue { 257 struct worker_pool *pool; /* I: the associated pool */ 258 struct workqueue_struct *wq; /* I: the owning workqueue */ 259 int work_color; /* L: current color */ 260 int flush_color; /* L: flushing color */ 261 int refcnt; /* L: reference count */ 262 int nr_in_flight[WORK_NR_COLORS]; 263 /* L: nr of in_flight works */ 264 bool plugged; /* L: execution suspended */ 265 266 /* 267 * nr_active management and WORK_STRUCT_INACTIVE: 268 * 269 * When pwq->nr_active >= max_active, new work item is queued to 270 * pwq->inactive_works instead of pool->worklist and marked with 271 * WORK_STRUCT_INACTIVE. 272 * 273 * All work items marked with WORK_STRUCT_INACTIVE do not participate in 274 * nr_active and all work items in pwq->inactive_works are marked with 275 * WORK_STRUCT_INACTIVE. But not all WORK_STRUCT_INACTIVE work items are 276 * in pwq->inactive_works. Some of them are ready to run in 277 * pool->worklist or worker->scheduled. Those work itmes are only struct 278 * wq_barrier which is used for flush_work() and should not participate 279 * in nr_active. For non-barrier work item, it is marked with 280 * WORK_STRUCT_INACTIVE iff it is in pwq->inactive_works. 281 */ 282 int nr_active; /* L: nr of active works */ 283 struct list_head inactive_works; /* L: inactive works */ 284 struct list_head pending_node; /* LN: node on wq_node_nr_active->pending_pwqs */ 285 struct list_head pwqs_node; /* WR: node on wq->pwqs */ 286 struct list_head mayday_node; /* MD: node on wq->maydays */ 287 288 u64 stats[PWQ_NR_STATS]; 289 290 /* 291 * Release of unbound pwq is punted to a kthread_worker. See put_pwq() 292 * and pwq_release_workfn() for details. pool_workqueue itself is also 293 * RCU protected so that the first pwq can be determined without 294 * grabbing wq->mutex. 295 */ 296 struct kthread_work release_work; 297 struct rcu_head rcu; 298 } __aligned(1 << WORK_STRUCT_PWQ_SHIFT); 299 300 /* 301 * Structure used to wait for workqueue flush. 302 */ 303 struct wq_flusher { 304 struct list_head list; /* WQ: list of flushers */ 305 int flush_color; /* WQ: flush color waiting for */ 306 struct completion done; /* flush completion */ 307 }; 308 309 struct wq_device; 310 311 /* 312 * Unlike in a per-cpu workqueue where max_active limits its concurrency level 313 * on each CPU, in an unbound workqueue, max_active applies to the whole system. 314 * As sharing a single nr_active across multiple sockets can be very expensive, 315 * the counting and enforcement is per NUMA node. 316 * 317 * The following struct is used to enforce per-node max_active. When a pwq wants 318 * to start executing a work item, it should increment ->nr using 319 * tryinc_node_nr_active(). If acquisition fails due to ->nr already being over 320 * ->max, the pwq is queued on ->pending_pwqs. As in-flight work items finish 321 * and decrement ->nr, node_activate_pending_pwq() activates the pending pwqs in 322 * round-robin order. 323 */ 324 struct wq_node_nr_active { 325 int max; /* per-node max_active */ 326 atomic_t nr; /* per-node nr_active */ 327 raw_spinlock_t lock; /* nests inside pool locks */ 328 struct list_head pending_pwqs; /* LN: pwqs with inactive works */ 329 }; 330 331 /* 332 * The externally visible workqueue. It relays the issued work items to 333 * the appropriate worker_pool through its pool_workqueues. 334 */ 335 struct workqueue_struct { 336 struct list_head pwqs; /* WR: all pwqs of this wq */ 337 struct list_head list; /* PR: list of all workqueues */ 338 339 struct mutex mutex; /* protects this wq */ 340 int work_color; /* WQ: current work color */ 341 int flush_color; /* WQ: current flush color */ 342 atomic_t nr_pwqs_to_flush; /* flush in progress */ 343 struct wq_flusher *first_flusher; /* WQ: first flusher */ 344 struct list_head flusher_queue; /* WQ: flush waiters */ 345 struct list_head flusher_overflow; /* WQ: flush overflow list */ 346 347 struct list_head maydays; /* MD: pwqs requesting rescue */ 348 struct worker *rescuer; /* MD: rescue worker */ 349 350 int nr_drainers; /* WQ: drain in progress */ 351 352 /* See alloc_workqueue() function comment for info on min/max_active */ 353 int max_active; /* WO: max active works */ 354 int min_active; /* WO: min active works */ 355 int saved_max_active; /* WQ: saved max_active */ 356 int saved_min_active; /* WQ: saved min_active */ 357 358 struct workqueue_attrs *unbound_attrs; /* PW: only for unbound wqs */ 359 struct pool_workqueue __rcu *dfl_pwq; /* PW: only for unbound wqs */ 360 361 #ifdef CONFIG_SYSFS 362 struct wq_device *wq_dev; /* I: for sysfs interface */ 363 #endif 364 #ifdef CONFIG_LOCKDEP 365 char *lock_name; 366 struct lock_class_key key; 367 struct lockdep_map __lockdep_map; 368 struct lockdep_map *lockdep_map; 369 #endif 370 char name[WQ_NAME_LEN]; /* I: workqueue name */ 371 372 /* 373 * Destruction of workqueue_struct is RCU protected to allow walking 374 * the workqueues list without grabbing wq_pool_mutex. 375 * This is used to dump all workqueues from sysrq. 376 */ 377 struct rcu_head rcu; 378 379 /* hot fields used during command issue, aligned to cacheline */ 380 unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */ 381 struct pool_workqueue __rcu * __percpu *cpu_pwq; /* I: per-cpu pwqs */ 382 struct wq_node_nr_active *node_nr_active[]; /* I: per-node nr_active */ 383 }; 384 385 /* 386 * Each pod type describes how CPUs should be grouped for unbound workqueues. 387 * See the comment above workqueue_attrs->affn_scope. 388 */ 389 struct wq_pod_type { 390 int nr_pods; /* number of pods */ 391 cpumask_var_t *pod_cpus; /* pod -> cpus */ 392 int *pod_node; /* pod -> node */ 393 int *cpu_pod; /* cpu -> pod */ 394 }; 395 396 struct work_offq_data { 397 u32 pool_id; 398 u32 disable; 399 u32 flags; 400 }; 401 402 static const char *wq_affn_names[WQ_AFFN_NR_TYPES] = { 403 [WQ_AFFN_DFL] = "default", 404 [WQ_AFFN_CPU] = "cpu", 405 [WQ_AFFN_SMT] = "smt", 406 [WQ_AFFN_CACHE] = "cache", 407 [WQ_AFFN_NUMA] = "numa", 408 [WQ_AFFN_SYSTEM] = "system", 409 }; 410 411 /* 412 * Per-cpu work items which run for longer than the following threshold are 413 * automatically considered CPU intensive and excluded from concurrency 414 * management to prevent them from noticeably delaying other per-cpu work items. 415 * ULONG_MAX indicates that the user hasn't overridden it with a boot parameter. 416 * The actual value is initialized in wq_cpu_intensive_thresh_init(). 417 */ 418 static unsigned long wq_cpu_intensive_thresh_us = ULONG_MAX; 419 module_param_named(cpu_intensive_thresh_us, wq_cpu_intensive_thresh_us, ulong, 0644); 420 #ifdef CONFIG_WQ_CPU_INTENSIVE_REPORT 421 static unsigned int wq_cpu_intensive_warning_thresh = 4; 422 module_param_named(cpu_intensive_warning_thresh, wq_cpu_intensive_warning_thresh, uint, 0644); 423 #endif 424 425 /* see the comment above the definition of WQ_POWER_EFFICIENT */ 426 static bool wq_power_efficient = IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT); 427 module_param_named(power_efficient, wq_power_efficient, bool, 0444); 428 429 static bool wq_online; /* can kworkers be created yet? */ 430 static bool wq_topo_initialized __read_mostly = false; 431 432 static struct kmem_cache *pwq_cache; 433 434 static struct wq_pod_type wq_pod_types[WQ_AFFN_NR_TYPES]; 435 static enum wq_affn_scope wq_affn_dfl = WQ_AFFN_CACHE; 436 437 /* buf for wq_update_unbound_pod_attrs(), protected by CPU hotplug exclusion */ 438 static struct workqueue_attrs *unbound_wq_update_pwq_attrs_buf; 439 440 static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */ 441 static DEFINE_MUTEX(wq_pool_attach_mutex); /* protects worker attach/detach */ 442 static DEFINE_RAW_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */ 443 /* wait for manager to go away */ 444 static struct rcuwait manager_wait = __RCUWAIT_INITIALIZER(manager_wait); 445 446 static LIST_HEAD(workqueues); /* PR: list of all workqueues */ 447 static bool workqueue_freezing; /* PL: have wqs started freezing? */ 448 449 /* PL: mirror the cpu_online_mask excluding the CPU in the midst of hotplugging */ 450 static cpumask_var_t wq_online_cpumask; 451 452 /* PL&A: allowable cpus for unbound wqs and work items */ 453 static cpumask_var_t wq_unbound_cpumask; 454 455 /* PL: user requested unbound cpumask via sysfs */ 456 static cpumask_var_t wq_requested_unbound_cpumask; 457 458 /* PL: isolated cpumask to be excluded from unbound cpumask */ 459 static cpumask_var_t wq_isolated_cpumask; 460 461 /* for further constrain wq_unbound_cpumask by cmdline parameter*/ 462 static struct cpumask wq_cmdline_cpumask __initdata; 463 464 /* CPU where unbound work was last round robin scheduled from this CPU */ 465 static DEFINE_PER_CPU(int, wq_rr_cpu_last); 466 467 /* 468 * Local execution of unbound work items is no longer guaranteed. The 469 * following always forces round-robin CPU selection on unbound work items 470 * to uncover usages which depend on it. 471 */ 472 #ifdef CONFIG_DEBUG_WQ_FORCE_RR_CPU 473 static bool wq_debug_force_rr_cpu = true; 474 #else 475 static bool wq_debug_force_rr_cpu = false; 476 #endif 477 module_param_named(debug_force_rr_cpu, wq_debug_force_rr_cpu, bool, 0644); 478 479 /* to raise softirq for the BH worker pools on other CPUs */ 480 static DEFINE_PER_CPU_SHARED_ALIGNED(struct irq_work [NR_STD_WORKER_POOLS], bh_pool_irq_works); 481 482 /* the BH worker pools */ 483 static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], bh_worker_pools); 484 485 /* the per-cpu worker pools */ 486 static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], cpu_worker_pools); 487 488 static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */ 489 490 /* PL: hash of all unbound pools keyed by pool->attrs */ 491 static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER); 492 493 /* I: attributes used when instantiating standard unbound pools on demand */ 494 static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS]; 495 496 /* I: attributes used when instantiating ordered pools on demand */ 497 static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS]; 498 499 /* 500 * I: kthread_worker to release pwq's. pwq release needs to be bounced to a 501 * process context while holding a pool lock. Bounce to a dedicated kthread 502 * worker to avoid A-A deadlocks. 503 */ 504 static struct kthread_worker *pwq_release_worker __ro_after_init; 505 506 struct workqueue_struct *system_wq __ro_after_init; 507 EXPORT_SYMBOL(system_wq); 508 struct workqueue_struct *system_highpri_wq __ro_after_init; 509 EXPORT_SYMBOL_GPL(system_highpri_wq); 510 struct workqueue_struct *system_long_wq __ro_after_init; 511 EXPORT_SYMBOL_GPL(system_long_wq); 512 struct workqueue_struct *system_unbound_wq __ro_after_init; 513 EXPORT_SYMBOL_GPL(system_unbound_wq); 514 struct workqueue_struct *system_freezable_wq __ro_after_init; 515 EXPORT_SYMBOL_GPL(system_freezable_wq); 516 struct workqueue_struct *system_power_efficient_wq __ro_after_init; 517 EXPORT_SYMBOL_GPL(system_power_efficient_wq); 518 struct workqueue_struct *system_freezable_power_efficient_wq __ro_after_init; 519 EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq); 520 struct workqueue_struct *system_bh_wq; 521 EXPORT_SYMBOL_GPL(system_bh_wq); 522 struct workqueue_struct *system_bh_highpri_wq; 523 EXPORT_SYMBOL_GPL(system_bh_highpri_wq); 524 525 static int worker_thread(void *__worker); 526 static void workqueue_sysfs_unregister(struct workqueue_struct *wq); 527 static void show_pwq(struct pool_workqueue *pwq); 528 static void show_one_worker_pool(struct worker_pool *pool); 529 530 #define CREATE_TRACE_POINTS 531 #include <trace/events/workqueue.h> 532 533 #define assert_rcu_or_pool_mutex() \ 534 RCU_LOCKDEP_WARN(!rcu_read_lock_any_held() && \ 535 !lockdep_is_held(&wq_pool_mutex), \ 536 "RCU or wq_pool_mutex should be held") 537 538 #define assert_rcu_or_wq_mutex_or_pool_mutex(wq) \ 539 RCU_LOCKDEP_WARN(!rcu_read_lock_any_held() && \ 540 !lockdep_is_held(&wq->mutex) && \ 541 !lockdep_is_held(&wq_pool_mutex), \ 542 "RCU, wq->mutex or wq_pool_mutex should be held") 543 544 #define for_each_bh_worker_pool(pool, cpu) \ 545 for ((pool) = &per_cpu(bh_worker_pools, cpu)[0]; \ 546 (pool) < &per_cpu(bh_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \ 547 (pool)++) 548 549 #define for_each_cpu_worker_pool(pool, cpu) \ 550 for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \ 551 (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \ 552 (pool)++) 553 554 /** 555 * for_each_pool - iterate through all worker_pools in the system 556 * @pool: iteration cursor 557 * @pi: integer used for iteration 558 * 559 * This must be called either with wq_pool_mutex held or RCU read 560 * locked. If the pool needs to be used beyond the locking in effect, the 561 * caller is responsible for guaranteeing that the pool stays online. 562 * 563 * The if/else clause exists only for the lockdep assertion and can be 564 * ignored. 565 */ 566 #define for_each_pool(pool, pi) \ 567 idr_for_each_entry(&worker_pool_idr, pool, pi) \ 568 if (({ assert_rcu_or_pool_mutex(); false; })) { } \ 569 else 570 571 /** 572 * for_each_pool_worker - iterate through all workers of a worker_pool 573 * @worker: iteration cursor 574 * @pool: worker_pool to iterate workers of 575 * 576 * This must be called with wq_pool_attach_mutex. 577 * 578 * The if/else clause exists only for the lockdep assertion and can be 579 * ignored. 580 */ 581 #define for_each_pool_worker(worker, pool) \ 582 list_for_each_entry((worker), &(pool)->workers, node) \ 583 if (({ lockdep_assert_held(&wq_pool_attach_mutex); false; })) { } \ 584 else 585 586 /** 587 * for_each_pwq - iterate through all pool_workqueues of the specified workqueue 588 * @pwq: iteration cursor 589 * @wq: the target workqueue 590 * 591 * This must be called either with wq->mutex held or RCU read locked. 592 * If the pwq needs to be used beyond the locking in effect, the caller is 593 * responsible for guaranteeing that the pwq stays online. 594 * 595 * The if/else clause exists only for the lockdep assertion and can be 596 * ignored. 597 */ 598 #define for_each_pwq(pwq, wq) \ 599 list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node, \ 600 lockdep_is_held(&(wq->mutex))) 601 602 #ifdef CONFIG_DEBUG_OBJECTS_WORK 603 604 static const struct debug_obj_descr work_debug_descr; 605 606 static void *work_debug_hint(void *addr) 607 { 608 return ((struct work_struct *) addr)->func; 609 } 610 611 static bool work_is_static_object(void *addr) 612 { 613 struct work_struct *work = addr; 614 615 return test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work)); 616 } 617 618 /* 619 * fixup_init is called when: 620 * - an active object is initialized 621 */ 622 static bool work_fixup_init(void *addr, enum debug_obj_state state) 623 { 624 struct work_struct *work = addr; 625 626 switch (state) { 627 case ODEBUG_STATE_ACTIVE: 628 cancel_work_sync(work); 629 debug_object_init(work, &work_debug_descr); 630 return true; 631 default: 632 return false; 633 } 634 } 635 636 /* 637 * fixup_free is called when: 638 * - an active object is freed 639 */ 640 static bool work_fixup_free(void *addr, enum debug_obj_state state) 641 { 642 struct work_struct *work = addr; 643 644 switch (state) { 645 case ODEBUG_STATE_ACTIVE: 646 cancel_work_sync(work); 647 debug_object_free(work, &work_debug_descr); 648 return true; 649 default: 650 return false; 651 } 652 } 653 654 static const struct debug_obj_descr work_debug_descr = { 655 .name = "work_struct", 656 .debug_hint = work_debug_hint, 657 .is_static_object = work_is_static_object, 658 .fixup_init = work_fixup_init, 659 .fixup_free = work_fixup_free, 660 }; 661 662 static inline void debug_work_activate(struct work_struct *work) 663 { 664 debug_object_activate(work, &work_debug_descr); 665 } 666 667 static inline void debug_work_deactivate(struct work_struct *work) 668 { 669 debug_object_deactivate(work, &work_debug_descr); 670 } 671 672 void __init_work(struct work_struct *work, int onstack) 673 { 674 if (onstack) 675 debug_object_init_on_stack(work, &work_debug_descr); 676 else 677 debug_object_init(work, &work_debug_descr); 678 } 679 EXPORT_SYMBOL_GPL(__init_work); 680 681 void destroy_work_on_stack(struct work_struct *work) 682 { 683 debug_object_free(work, &work_debug_descr); 684 } 685 EXPORT_SYMBOL_GPL(destroy_work_on_stack); 686 687 void destroy_delayed_work_on_stack(struct delayed_work *work) 688 { 689 destroy_timer_on_stack(&work->timer); 690 debug_object_free(&work->work, &work_debug_descr); 691 } 692 EXPORT_SYMBOL_GPL(destroy_delayed_work_on_stack); 693 694 #else 695 static inline void debug_work_activate(struct work_struct *work) { } 696 static inline void debug_work_deactivate(struct work_struct *work) { } 697 #endif 698 699 /** 700 * worker_pool_assign_id - allocate ID and assign it to @pool 701 * @pool: the pool pointer of interest 702 * 703 * Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned 704 * successfully, -errno on failure. 705 */ 706 static int worker_pool_assign_id(struct worker_pool *pool) 707 { 708 int ret; 709 710 lockdep_assert_held(&wq_pool_mutex); 711 712 ret = idr_alloc(&worker_pool_idr, pool, 0, WORK_OFFQ_POOL_NONE, 713 GFP_KERNEL); 714 if (ret >= 0) { 715 pool->id = ret; 716 return 0; 717 } 718 return ret; 719 } 720 721 static struct pool_workqueue __rcu ** 722 unbound_pwq_slot(struct workqueue_struct *wq, int cpu) 723 { 724 if (cpu >= 0) 725 return per_cpu_ptr(wq->cpu_pwq, cpu); 726 else 727 return &wq->dfl_pwq; 728 } 729 730 /* @cpu < 0 for dfl_pwq */ 731 static struct pool_workqueue *unbound_pwq(struct workqueue_struct *wq, int cpu) 732 { 733 return rcu_dereference_check(*unbound_pwq_slot(wq, cpu), 734 lockdep_is_held(&wq_pool_mutex) || 735 lockdep_is_held(&wq->mutex)); 736 } 737 738 /** 739 * unbound_effective_cpumask - effective cpumask of an unbound workqueue 740 * @wq: workqueue of interest 741 * 742 * @wq->unbound_attrs->cpumask contains the cpumask requested by the user which 743 * is masked with wq_unbound_cpumask to determine the effective cpumask. The 744 * default pwq is always mapped to the pool with the current effective cpumask. 745 */ 746 static struct cpumask *unbound_effective_cpumask(struct workqueue_struct *wq) 747 { 748 return unbound_pwq(wq, -1)->pool->attrs->__pod_cpumask; 749 } 750 751 static unsigned int work_color_to_flags(int color) 752 { 753 return color << WORK_STRUCT_COLOR_SHIFT; 754 } 755 756 static int get_work_color(unsigned long work_data) 757 { 758 return (work_data >> WORK_STRUCT_COLOR_SHIFT) & 759 ((1 << WORK_STRUCT_COLOR_BITS) - 1); 760 } 761 762 static int work_next_color(int color) 763 { 764 return (color + 1) % WORK_NR_COLORS; 765 } 766 767 static unsigned long pool_offq_flags(struct worker_pool *pool) 768 { 769 return (pool->flags & POOL_BH) ? WORK_OFFQ_BH : 0; 770 } 771 772 /* 773 * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data 774 * contain the pointer to the queued pwq. Once execution starts, the flag 775 * is cleared and the high bits contain OFFQ flags and pool ID. 776 * 777 * set_work_pwq(), set_work_pool_and_clear_pending() and mark_work_canceling() 778 * can be used to set the pwq, pool or clear work->data. These functions should 779 * only be called while the work is owned - ie. while the PENDING bit is set. 780 * 781 * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq 782 * corresponding to a work. Pool is available once the work has been 783 * queued anywhere after initialization until it is sync canceled. pwq is 784 * available only while the work item is queued. 785 */ 786 static inline void set_work_data(struct work_struct *work, unsigned long data) 787 { 788 WARN_ON_ONCE(!work_pending(work)); 789 atomic_long_set(&work->data, data | work_static(work)); 790 } 791 792 static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq, 793 unsigned long flags) 794 { 795 set_work_data(work, (unsigned long)pwq | WORK_STRUCT_PENDING | 796 WORK_STRUCT_PWQ | flags); 797 } 798 799 static void set_work_pool_and_keep_pending(struct work_struct *work, 800 int pool_id, unsigned long flags) 801 { 802 set_work_data(work, ((unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT) | 803 WORK_STRUCT_PENDING | flags); 804 } 805 806 static void set_work_pool_and_clear_pending(struct work_struct *work, 807 int pool_id, unsigned long flags) 808 { 809 /* 810 * The following wmb is paired with the implied mb in 811 * test_and_set_bit(PENDING) and ensures all updates to @work made 812 * here are visible to and precede any updates by the next PENDING 813 * owner. 814 */ 815 smp_wmb(); 816 set_work_data(work, ((unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT) | 817 flags); 818 /* 819 * The following mb guarantees that previous clear of a PENDING bit 820 * will not be reordered with any speculative LOADS or STORES from 821 * work->current_func, which is executed afterwards. This possible 822 * reordering can lead to a missed execution on attempt to queue 823 * the same @work. E.g. consider this case: 824 * 825 * CPU#0 CPU#1 826 * ---------------------------- -------------------------------- 827 * 828 * 1 STORE event_indicated 829 * 2 queue_work_on() { 830 * 3 test_and_set_bit(PENDING) 831 * 4 } set_..._and_clear_pending() { 832 * 5 set_work_data() # clear bit 833 * 6 smp_mb() 834 * 7 work->current_func() { 835 * 8 LOAD event_indicated 836 * } 837 * 838 * Without an explicit full barrier speculative LOAD on line 8 can 839 * be executed before CPU#0 does STORE on line 1. If that happens, 840 * CPU#0 observes the PENDING bit is still set and new execution of 841 * a @work is not queued in a hope, that CPU#1 will eventually 842 * finish the queued @work. Meanwhile CPU#1 does not see 843 * event_indicated is set, because speculative LOAD was executed 844 * before actual STORE. 845 */ 846 smp_mb(); 847 } 848 849 static inline struct pool_workqueue *work_struct_pwq(unsigned long data) 850 { 851 return (struct pool_workqueue *)(data & WORK_STRUCT_PWQ_MASK); 852 } 853 854 static struct pool_workqueue *get_work_pwq(struct work_struct *work) 855 { 856 unsigned long data = atomic_long_read(&work->data); 857 858 if (data & WORK_STRUCT_PWQ) 859 return work_struct_pwq(data); 860 else 861 return NULL; 862 } 863 864 /** 865 * get_work_pool - return the worker_pool a given work was associated with 866 * @work: the work item of interest 867 * 868 * Pools are created and destroyed under wq_pool_mutex, and allows read 869 * access under RCU read lock. As such, this function should be 870 * called under wq_pool_mutex or inside of a rcu_read_lock() region. 871 * 872 * All fields of the returned pool are accessible as long as the above 873 * mentioned locking is in effect. If the returned pool needs to be used 874 * beyond the critical section, the caller is responsible for ensuring the 875 * returned pool is and stays online. 876 * 877 * Return: The worker_pool @work was last associated with. %NULL if none. 878 */ 879 static struct worker_pool *get_work_pool(struct work_struct *work) 880 { 881 unsigned long data = atomic_long_read(&work->data); 882 int pool_id; 883 884 assert_rcu_or_pool_mutex(); 885 886 if (data & WORK_STRUCT_PWQ) 887 return work_struct_pwq(data)->pool; 888 889 pool_id = data >> WORK_OFFQ_POOL_SHIFT; 890 if (pool_id == WORK_OFFQ_POOL_NONE) 891 return NULL; 892 893 return idr_find(&worker_pool_idr, pool_id); 894 } 895 896 static unsigned long shift_and_mask(unsigned long v, u32 shift, u32 bits) 897 { 898 return (v >> shift) & ((1U << bits) - 1); 899 } 900 901 static void work_offqd_unpack(struct work_offq_data *offqd, unsigned long data) 902 { 903 WARN_ON_ONCE(data & WORK_STRUCT_PWQ); 904 905 offqd->pool_id = shift_and_mask(data, WORK_OFFQ_POOL_SHIFT, 906 WORK_OFFQ_POOL_BITS); 907 offqd->disable = shift_and_mask(data, WORK_OFFQ_DISABLE_SHIFT, 908 WORK_OFFQ_DISABLE_BITS); 909 offqd->flags = data & WORK_OFFQ_FLAG_MASK; 910 } 911 912 static unsigned long work_offqd_pack_flags(struct work_offq_data *offqd) 913 { 914 return ((unsigned long)offqd->disable << WORK_OFFQ_DISABLE_SHIFT) | 915 ((unsigned long)offqd->flags); 916 } 917 918 /* 919 * Policy functions. These define the policies on how the global worker 920 * pools are managed. Unless noted otherwise, these functions assume that 921 * they're being called with pool->lock held. 922 */ 923 924 /* 925 * Need to wake up a worker? Called from anything but currently 926 * running workers. 927 * 928 * Note that, because unbound workers never contribute to nr_running, this 929 * function will always return %true for unbound pools as long as the 930 * worklist isn't empty. 931 */ 932 static bool need_more_worker(struct worker_pool *pool) 933 { 934 return !list_empty(&pool->worklist) && !pool->nr_running; 935 } 936 937 /* Can I start working? Called from busy but !running workers. */ 938 static bool may_start_working(struct worker_pool *pool) 939 { 940 return pool->nr_idle; 941 } 942 943 /* Do I need to keep working? Called from currently running workers. */ 944 static bool keep_working(struct worker_pool *pool) 945 { 946 return !list_empty(&pool->worklist) && (pool->nr_running <= 1); 947 } 948 949 /* Do we need a new worker? Called from manager. */ 950 static bool need_to_create_worker(struct worker_pool *pool) 951 { 952 return need_more_worker(pool) && !may_start_working(pool); 953 } 954 955 /* Do we have too many workers and should some go away? */ 956 static bool too_many_workers(struct worker_pool *pool) 957 { 958 bool managing = pool->flags & POOL_MANAGER_ACTIVE; 959 int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ 960 int nr_busy = pool->nr_workers - nr_idle; 961 962 return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; 963 } 964 965 /** 966 * worker_set_flags - set worker flags and adjust nr_running accordingly 967 * @worker: self 968 * @flags: flags to set 969 * 970 * Set @flags in @worker->flags and adjust nr_running accordingly. 971 */ 972 static inline void worker_set_flags(struct worker *worker, unsigned int flags) 973 { 974 struct worker_pool *pool = worker->pool; 975 976 lockdep_assert_held(&pool->lock); 977 978 /* If transitioning into NOT_RUNNING, adjust nr_running. */ 979 if ((flags & WORKER_NOT_RUNNING) && 980 !(worker->flags & WORKER_NOT_RUNNING)) { 981 pool->nr_running--; 982 } 983 984 worker->flags |= flags; 985 } 986 987 /** 988 * worker_clr_flags - clear worker flags and adjust nr_running accordingly 989 * @worker: self 990 * @flags: flags to clear 991 * 992 * Clear @flags in @worker->flags and adjust nr_running accordingly. 993 */ 994 static inline void worker_clr_flags(struct worker *worker, unsigned int flags) 995 { 996 struct worker_pool *pool = worker->pool; 997 unsigned int oflags = worker->flags; 998 999 lockdep_assert_held(&pool->lock); 1000 1001 worker->flags &= ~flags; 1002 1003 /* 1004 * If transitioning out of NOT_RUNNING, increment nr_running. Note 1005 * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask 1006 * of multiple flags, not a single flag. 1007 */ 1008 if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) 1009 if (!(worker->flags & WORKER_NOT_RUNNING)) 1010 pool->nr_running++; 1011 } 1012 1013 /* Return the first idle worker. Called with pool->lock held. */ 1014 static struct worker *first_idle_worker(struct worker_pool *pool) 1015 { 1016 if (unlikely(list_empty(&pool->idle_list))) 1017 return NULL; 1018 1019 return list_first_entry(&pool->idle_list, struct worker, entry); 1020 } 1021 1022 /** 1023 * worker_enter_idle - enter idle state 1024 * @worker: worker which is entering idle state 1025 * 1026 * @worker is entering idle state. Update stats and idle timer if 1027 * necessary. 1028 * 1029 * LOCKING: 1030 * raw_spin_lock_irq(pool->lock). 1031 */ 1032 static void worker_enter_idle(struct worker *worker) 1033 { 1034 struct worker_pool *pool = worker->pool; 1035 1036 if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) || 1037 WARN_ON_ONCE(!list_empty(&worker->entry) && 1038 (worker->hentry.next || worker->hentry.pprev))) 1039 return; 1040 1041 /* can't use worker_set_flags(), also called from create_worker() */ 1042 worker->flags |= WORKER_IDLE; 1043 pool->nr_idle++; 1044 worker->last_active = jiffies; 1045 1046 /* idle_list is LIFO */ 1047 list_add(&worker->entry, &pool->idle_list); 1048 1049 if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) 1050 mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); 1051 1052 /* Sanity check nr_running. */ 1053 WARN_ON_ONCE(pool->nr_workers == pool->nr_idle && pool->nr_running); 1054 } 1055 1056 /** 1057 * worker_leave_idle - leave idle state 1058 * @worker: worker which is leaving idle state 1059 * 1060 * @worker is leaving idle state. Update stats. 1061 * 1062 * LOCKING: 1063 * raw_spin_lock_irq(pool->lock). 1064 */ 1065 static void worker_leave_idle(struct worker *worker) 1066 { 1067 struct worker_pool *pool = worker->pool; 1068 1069 if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE))) 1070 return; 1071 worker_clr_flags(worker, WORKER_IDLE); 1072 pool->nr_idle--; 1073 list_del_init(&worker->entry); 1074 } 1075 1076 /** 1077 * find_worker_executing_work - find worker which is executing a work 1078 * @pool: pool of interest 1079 * @work: work to find worker for 1080 * 1081 * Find a worker which is executing @work on @pool by searching 1082 * @pool->busy_hash which is keyed by the address of @work. For a worker 1083 * to match, its current execution should match the address of @work and 1084 * its work function. This is to avoid unwanted dependency between 1085 * unrelated work executions through a work item being recycled while still 1086 * being executed. 1087 * 1088 * This is a bit tricky. A work item may be freed once its execution 1089 * starts and nothing prevents the freed area from being recycled for 1090 * another work item. If the same work item address ends up being reused 1091 * before the original execution finishes, workqueue will identify the 1092 * recycled work item as currently executing and make it wait until the 1093 * current execution finishes, introducing an unwanted dependency. 1094 * 1095 * This function checks the work item address and work function to avoid 1096 * false positives. Note that this isn't complete as one may construct a 1097 * work function which can introduce dependency onto itself through a 1098 * recycled work item. Well, if somebody wants to shoot oneself in the 1099 * foot that badly, there's only so much we can do, and if such deadlock 1100 * actually occurs, it should be easy to locate the culprit work function. 1101 * 1102 * CONTEXT: 1103 * raw_spin_lock_irq(pool->lock). 1104 * 1105 * Return: 1106 * Pointer to worker which is executing @work if found, %NULL 1107 * otherwise. 1108 */ 1109 static struct worker *find_worker_executing_work(struct worker_pool *pool, 1110 struct work_struct *work) 1111 { 1112 struct worker *worker; 1113 1114 hash_for_each_possible(pool->busy_hash, worker, hentry, 1115 (unsigned long)work) 1116 if (worker->current_work == work && 1117 worker->current_func == work->func) 1118 return worker; 1119 1120 return NULL; 1121 } 1122 1123 /** 1124 * move_linked_works - move linked works to a list 1125 * @work: start of series of works to be scheduled 1126 * @head: target list to append @work to 1127 * @nextp: out parameter for nested worklist walking 1128 * 1129 * Schedule linked works starting from @work to @head. Work series to be 1130 * scheduled starts at @work and includes any consecutive work with 1131 * WORK_STRUCT_LINKED set in its predecessor. See assign_work() for details on 1132 * @nextp. 1133 * 1134 * CONTEXT: 1135 * raw_spin_lock_irq(pool->lock). 1136 */ 1137 static void move_linked_works(struct work_struct *work, struct list_head *head, 1138 struct work_struct **nextp) 1139 { 1140 struct work_struct *n; 1141 1142 /* 1143 * Linked worklist will always end before the end of the list, 1144 * use NULL for list head. 1145 */ 1146 list_for_each_entry_safe_from(work, n, NULL, entry) { 1147 list_move_tail(&work->entry, head); 1148 if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) 1149 break; 1150 } 1151 1152 /* 1153 * If we're already inside safe list traversal and have moved 1154 * multiple works to the scheduled queue, the next position 1155 * needs to be updated. 1156 */ 1157 if (nextp) 1158 *nextp = n; 1159 } 1160 1161 /** 1162 * assign_work - assign a work item and its linked work items to a worker 1163 * @work: work to assign 1164 * @worker: worker to assign to 1165 * @nextp: out parameter for nested worklist walking 1166 * 1167 * Assign @work and its linked work items to @worker. If @work is already being 1168 * executed by another worker in the same pool, it'll be punted there. 1169 * 1170 * If @nextp is not NULL, it's updated to point to the next work of the last 1171 * scheduled work. This allows assign_work() to be nested inside 1172 * list_for_each_entry_safe(). 1173 * 1174 * Returns %true if @work was successfully assigned to @worker. %false if @work 1175 * was punted to another worker already executing it. 1176 */ 1177 static bool assign_work(struct work_struct *work, struct worker *worker, 1178 struct work_struct **nextp) 1179 { 1180 struct worker_pool *pool = worker->pool; 1181 struct worker *collision; 1182 1183 lockdep_assert_held(&pool->lock); 1184 1185 /* 1186 * A single work shouldn't be executed concurrently by multiple workers. 1187 * __queue_work() ensures that @work doesn't jump to a different pool 1188 * while still running in the previous pool. Here, we should ensure that 1189 * @work is not executed concurrently by multiple workers from the same 1190 * pool. Check whether anyone is already processing the work. If so, 1191 * defer the work to the currently executing one. 1192 */ 1193 collision = find_worker_executing_work(pool, work); 1194 if (unlikely(collision)) { 1195 move_linked_works(work, &collision->scheduled, nextp); 1196 return false; 1197 } 1198 1199 move_linked_works(work, &worker->scheduled, nextp); 1200 return true; 1201 } 1202 1203 static struct irq_work *bh_pool_irq_work(struct worker_pool *pool) 1204 { 1205 int high = pool->attrs->nice == HIGHPRI_NICE_LEVEL ? 1 : 0; 1206 1207 return &per_cpu(bh_pool_irq_works, pool->cpu)[high]; 1208 } 1209 1210 static void kick_bh_pool(struct worker_pool *pool) 1211 { 1212 #ifdef CONFIG_SMP 1213 /* see drain_dead_softirq_workfn() for BH_DRAINING */ 1214 if (unlikely(pool->cpu != smp_processor_id() && 1215 !(pool->flags & POOL_BH_DRAINING))) { 1216 irq_work_queue_on(bh_pool_irq_work(pool), pool->cpu); 1217 return; 1218 } 1219 #endif 1220 if (pool->attrs->nice == HIGHPRI_NICE_LEVEL) 1221 raise_softirq_irqoff(HI_SOFTIRQ); 1222 else 1223 raise_softirq_irqoff(TASKLET_SOFTIRQ); 1224 } 1225 1226 /** 1227 * kick_pool - wake up an idle worker if necessary 1228 * @pool: pool to kick 1229 * 1230 * @pool may have pending work items. Wake up worker if necessary. Returns 1231 * whether a worker was woken up. 1232 */ 1233 static bool kick_pool(struct worker_pool *pool) 1234 { 1235 struct worker *worker = first_idle_worker(pool); 1236 struct task_struct *p; 1237 1238 lockdep_assert_held(&pool->lock); 1239 1240 if (!need_more_worker(pool) || !worker) 1241 return false; 1242 1243 if (pool->flags & POOL_BH) { 1244 kick_bh_pool(pool); 1245 return true; 1246 } 1247 1248 p = worker->task; 1249 1250 #ifdef CONFIG_SMP 1251 /* 1252 * Idle @worker is about to execute @work and waking up provides an 1253 * opportunity to migrate @worker at a lower cost by setting the task's 1254 * wake_cpu field. Let's see if we want to move @worker to improve 1255 * execution locality. 1256 * 1257 * We're waking the worker that went idle the latest and there's some 1258 * chance that @worker is marked idle but hasn't gone off CPU yet. If 1259 * so, setting the wake_cpu won't do anything. As this is a best-effort 1260 * optimization and the race window is narrow, let's leave as-is for 1261 * now. If this becomes pronounced, we can skip over workers which are 1262 * still on cpu when picking an idle worker. 1263 * 1264 * If @pool has non-strict affinity, @worker might have ended up outside 1265 * its affinity scope. Repatriate. 1266 */ 1267 if (!pool->attrs->affn_strict && 1268 !cpumask_test_cpu(p->wake_cpu, pool->attrs->__pod_cpumask)) { 1269 struct work_struct *work = list_first_entry(&pool->worklist, 1270 struct work_struct, entry); 1271 int wake_cpu = cpumask_any_and_distribute(pool->attrs->__pod_cpumask, 1272 cpu_online_mask); 1273 if (wake_cpu < nr_cpu_ids) { 1274 p->wake_cpu = wake_cpu; 1275 get_work_pwq(work)->stats[PWQ_STAT_REPATRIATED]++; 1276 } 1277 } 1278 #endif 1279 wake_up_process(p); 1280 return true; 1281 } 1282 1283 #ifdef CONFIG_WQ_CPU_INTENSIVE_REPORT 1284 1285 /* 1286 * Concurrency-managed per-cpu work items that hog CPU for longer than 1287 * wq_cpu_intensive_thresh_us trigger the automatic CPU_INTENSIVE mechanism, 1288 * which prevents them from stalling other concurrency-managed work items. If a 1289 * work function keeps triggering this mechanism, it's likely that the work item 1290 * should be using an unbound workqueue instead. 1291 * 1292 * wq_cpu_intensive_report() tracks work functions which trigger such conditions 1293 * and report them so that they can be examined and converted to use unbound 1294 * workqueues as appropriate. To avoid flooding the console, each violating work 1295 * function is tracked and reported with exponential backoff. 1296 */ 1297 #define WCI_MAX_ENTS 128 1298 1299 struct wci_ent { 1300 work_func_t func; 1301 atomic64_t cnt; 1302 struct hlist_node hash_node; 1303 }; 1304 1305 static struct wci_ent wci_ents[WCI_MAX_ENTS]; 1306 static int wci_nr_ents; 1307 static DEFINE_RAW_SPINLOCK(wci_lock); 1308 static DEFINE_HASHTABLE(wci_hash, ilog2(WCI_MAX_ENTS)); 1309 1310 static struct wci_ent *wci_find_ent(work_func_t func) 1311 { 1312 struct wci_ent *ent; 1313 1314 hash_for_each_possible_rcu(wci_hash, ent, hash_node, 1315 (unsigned long)func) { 1316 if (ent->func == func) 1317 return ent; 1318 } 1319 return NULL; 1320 } 1321 1322 static void wq_cpu_intensive_report(work_func_t func) 1323 { 1324 struct wci_ent *ent; 1325 1326 restart: 1327 ent = wci_find_ent(func); 1328 if (ent) { 1329 u64 cnt; 1330 1331 /* 1332 * Start reporting from the warning_thresh and back off 1333 * exponentially. 1334 */ 1335 cnt = atomic64_inc_return_relaxed(&ent->cnt); 1336 if (wq_cpu_intensive_warning_thresh && 1337 cnt >= wq_cpu_intensive_warning_thresh && 1338 is_power_of_2(cnt + 1 - wq_cpu_intensive_warning_thresh)) 1339 printk_deferred(KERN_WARNING "workqueue: %ps hogged CPU for >%luus %llu times, consider switching to WQ_UNBOUND\n", 1340 ent->func, wq_cpu_intensive_thresh_us, 1341 atomic64_read(&ent->cnt)); 1342 return; 1343 } 1344 1345 /* 1346 * @func is a new violation. Allocate a new entry for it. If wcn_ents[] 1347 * is exhausted, something went really wrong and we probably made enough 1348 * noise already. 1349 */ 1350 if (wci_nr_ents >= WCI_MAX_ENTS) 1351 return; 1352 1353 raw_spin_lock(&wci_lock); 1354 1355 if (wci_nr_ents >= WCI_MAX_ENTS) { 1356 raw_spin_unlock(&wci_lock); 1357 return; 1358 } 1359 1360 if (wci_find_ent(func)) { 1361 raw_spin_unlock(&wci_lock); 1362 goto restart; 1363 } 1364 1365 ent = &wci_ents[wci_nr_ents++]; 1366 ent->func = func; 1367 atomic64_set(&ent->cnt, 0); 1368 hash_add_rcu(wci_hash, &ent->hash_node, (unsigned long)func); 1369 1370 raw_spin_unlock(&wci_lock); 1371 1372 goto restart; 1373 } 1374 1375 #else /* CONFIG_WQ_CPU_INTENSIVE_REPORT */ 1376 static void wq_cpu_intensive_report(work_func_t func) {} 1377 #endif /* CONFIG_WQ_CPU_INTENSIVE_REPORT */ 1378 1379 /** 1380 * wq_worker_running - a worker is running again 1381 * @task: task waking up 1382 * 1383 * This function is called when a worker returns from schedule() 1384 */ 1385 void wq_worker_running(struct task_struct *task) 1386 { 1387 struct worker *worker = kthread_data(task); 1388 1389 if (!READ_ONCE(worker->sleeping)) 1390 return; 1391 1392 /* 1393 * If preempted by unbind_workers() between the WORKER_NOT_RUNNING check 1394 * and the nr_running increment below, we may ruin the nr_running reset 1395 * and leave with an unexpected pool->nr_running == 1 on the newly unbound 1396 * pool. Protect against such race. 1397 */ 1398 preempt_disable(); 1399 if (!(worker->flags & WORKER_NOT_RUNNING)) 1400 worker->pool->nr_running++; 1401 preempt_enable(); 1402 1403 /* 1404 * CPU intensive auto-detection cares about how long a work item hogged 1405 * CPU without sleeping. Reset the starting timestamp on wakeup. 1406 */ 1407 worker->current_at = worker->task->se.sum_exec_runtime; 1408 1409 WRITE_ONCE(worker->sleeping, 0); 1410 } 1411 1412 /** 1413 * wq_worker_sleeping - a worker is going to sleep 1414 * @task: task going to sleep 1415 * 1416 * This function is called from schedule() when a busy worker is 1417 * going to sleep. 1418 */ 1419 void wq_worker_sleeping(struct task_struct *task) 1420 { 1421 struct worker *worker = kthread_data(task); 1422 struct worker_pool *pool; 1423 1424 /* 1425 * Rescuers, which may not have all the fields set up like normal 1426 * workers, also reach here, let's not access anything before 1427 * checking NOT_RUNNING. 1428 */ 1429 if (worker->flags & WORKER_NOT_RUNNING) 1430 return; 1431 1432 pool = worker->pool; 1433 1434 /* Return if preempted before wq_worker_running() was reached */ 1435 if (READ_ONCE(worker->sleeping)) 1436 return; 1437 1438 WRITE_ONCE(worker->sleeping, 1); 1439 raw_spin_lock_irq(&pool->lock); 1440 1441 /* 1442 * Recheck in case unbind_workers() preempted us. We don't 1443 * want to decrement nr_running after the worker is unbound 1444 * and nr_running has been reset. 1445 */ 1446 if (worker->flags & WORKER_NOT_RUNNING) { 1447 raw_spin_unlock_irq(&pool->lock); 1448 return; 1449 } 1450 1451 pool->nr_running--; 1452 if (kick_pool(pool)) 1453 worker->current_pwq->stats[PWQ_STAT_CM_WAKEUP]++; 1454 1455 raw_spin_unlock_irq(&pool->lock); 1456 } 1457 1458 /** 1459 * wq_worker_tick - a scheduler tick occurred while a kworker is running 1460 * @task: task currently running 1461 * 1462 * Called from sched_tick(). We're in the IRQ context and the current 1463 * worker's fields which follow the 'K' locking rule can be accessed safely. 1464 */ 1465 void wq_worker_tick(struct task_struct *task) 1466 { 1467 struct worker *worker = kthread_data(task); 1468 struct pool_workqueue *pwq = worker->current_pwq; 1469 struct worker_pool *pool = worker->pool; 1470 1471 if (!pwq) 1472 return; 1473 1474 pwq->stats[PWQ_STAT_CPU_TIME] += TICK_USEC; 1475 1476 if (!wq_cpu_intensive_thresh_us) 1477 return; 1478 1479 /* 1480 * If the current worker is concurrency managed and hogged the CPU for 1481 * longer than wq_cpu_intensive_thresh_us, it's automatically marked 1482 * CPU_INTENSIVE to avoid stalling other concurrency-managed work items. 1483 * 1484 * Set @worker->sleeping means that @worker is in the process of 1485 * switching out voluntarily and won't be contributing to 1486 * @pool->nr_running until it wakes up. As wq_worker_sleeping() also 1487 * decrements ->nr_running, setting CPU_INTENSIVE here can lead to 1488 * double decrements. The task is releasing the CPU anyway. Let's skip. 1489 * We probably want to make this prettier in the future. 1490 */ 1491 if ((worker->flags & WORKER_NOT_RUNNING) || READ_ONCE(worker->sleeping) || 1492 worker->task->se.sum_exec_runtime - worker->current_at < 1493 wq_cpu_intensive_thresh_us * NSEC_PER_USEC) 1494 return; 1495 1496 raw_spin_lock(&pool->lock); 1497 1498 worker_set_flags(worker, WORKER_CPU_INTENSIVE); 1499 wq_cpu_intensive_report(worker->current_func); 1500 pwq->stats[PWQ_STAT_CPU_INTENSIVE]++; 1501 1502 if (kick_pool(pool)) 1503 pwq->stats[PWQ_STAT_CM_WAKEUP]++; 1504 1505 raw_spin_unlock(&pool->lock); 1506 } 1507 1508 /** 1509 * wq_worker_last_func - retrieve worker's last work function 1510 * @task: Task to retrieve last work function of. 1511 * 1512 * Determine the last function a worker executed. This is called from 1513 * the scheduler to get a worker's last known identity. 1514 * 1515 * CONTEXT: 1516 * raw_spin_lock_irq(rq->lock) 1517 * 1518 * This function is called during schedule() when a kworker is going 1519 * to sleep. It's used by psi to identify aggregation workers during 1520 * dequeuing, to allow periodic aggregation to shut-off when that 1521 * worker is the last task in the system or cgroup to go to sleep. 1522 * 1523 * As this function doesn't involve any workqueue-related locking, it 1524 * only returns stable values when called from inside the scheduler's 1525 * queuing and dequeuing paths, when @task, which must be a kworker, 1526 * is guaranteed to not be processing any works. 1527 * 1528 * Return: 1529 * The last work function %current executed as a worker, NULL if it 1530 * hasn't executed any work yet. 1531 */ 1532 work_func_t wq_worker_last_func(struct task_struct *task) 1533 { 1534 struct worker *worker = kthread_data(task); 1535 1536 return worker->last_func; 1537 } 1538 1539 /** 1540 * wq_node_nr_active - Determine wq_node_nr_active to use 1541 * @wq: workqueue of interest 1542 * @node: NUMA node, can be %NUMA_NO_NODE 1543 * 1544 * Determine wq_node_nr_active to use for @wq on @node. Returns: 1545 * 1546 * - %NULL for per-cpu workqueues as they don't need to use shared nr_active. 1547 * 1548 * - node_nr_active[nr_node_ids] if @node is %NUMA_NO_NODE. 1549 * 1550 * - Otherwise, node_nr_active[@node]. 1551 */ 1552 static struct wq_node_nr_active *wq_node_nr_active(struct workqueue_struct *wq, 1553 int node) 1554 { 1555 if (!(wq->flags & WQ_UNBOUND)) 1556 return NULL; 1557 1558 if (node == NUMA_NO_NODE) 1559 node = nr_node_ids; 1560 1561 return wq->node_nr_active[node]; 1562 } 1563 1564 /** 1565 * wq_update_node_max_active - Update per-node max_actives to use 1566 * @wq: workqueue to update 1567 * @off_cpu: CPU that's going down, -1 if a CPU is not going down 1568 * 1569 * Update @wq->node_nr_active[]->max. @wq must be unbound. max_active is 1570 * distributed among nodes according to the proportions of numbers of online 1571 * cpus. The result is always between @wq->min_active and max_active. 1572 */ 1573 static void wq_update_node_max_active(struct workqueue_struct *wq, int off_cpu) 1574 { 1575 struct cpumask *effective = unbound_effective_cpumask(wq); 1576 int min_active = READ_ONCE(wq->min_active); 1577 int max_active = READ_ONCE(wq->max_active); 1578 int total_cpus, node; 1579 1580 lockdep_assert_held(&wq->mutex); 1581 1582 if (!wq_topo_initialized) 1583 return; 1584 1585 if (off_cpu >= 0 && !cpumask_test_cpu(off_cpu, effective)) 1586 off_cpu = -1; 1587 1588 total_cpus = cpumask_weight_and(effective, cpu_online_mask); 1589 if (off_cpu >= 0) 1590 total_cpus--; 1591 1592 /* If all CPUs of the wq get offline, use the default values */ 1593 if (unlikely(!total_cpus)) { 1594 for_each_node(node) 1595 wq_node_nr_active(wq, node)->max = min_active; 1596 1597 wq_node_nr_active(wq, NUMA_NO_NODE)->max = max_active; 1598 return; 1599 } 1600 1601 for_each_node(node) { 1602 int node_cpus; 1603 1604 node_cpus = cpumask_weight_and(effective, cpumask_of_node(node)); 1605 if (off_cpu >= 0 && cpu_to_node(off_cpu) == node) 1606 node_cpus--; 1607 1608 wq_node_nr_active(wq, node)->max = 1609 clamp(DIV_ROUND_UP(max_active * node_cpus, total_cpus), 1610 min_active, max_active); 1611 } 1612 1613 wq_node_nr_active(wq, NUMA_NO_NODE)->max = max_active; 1614 } 1615 1616 /** 1617 * get_pwq - get an extra reference on the specified pool_workqueue 1618 * @pwq: pool_workqueue to get 1619 * 1620 * Obtain an extra reference on @pwq. The caller should guarantee that 1621 * @pwq has positive refcnt and be holding the matching pool->lock. 1622 */ 1623 static void get_pwq(struct pool_workqueue *pwq) 1624 { 1625 lockdep_assert_held(&pwq->pool->lock); 1626 WARN_ON_ONCE(pwq->refcnt <= 0); 1627 pwq->refcnt++; 1628 } 1629 1630 /** 1631 * put_pwq - put a pool_workqueue reference 1632 * @pwq: pool_workqueue to put 1633 * 1634 * Drop a reference of @pwq. If its refcnt reaches zero, schedule its 1635 * destruction. The caller should be holding the matching pool->lock. 1636 */ 1637 static void put_pwq(struct pool_workqueue *pwq) 1638 { 1639 lockdep_assert_held(&pwq->pool->lock); 1640 if (likely(--pwq->refcnt)) 1641 return; 1642 /* 1643 * @pwq can't be released under pool->lock, bounce to a dedicated 1644 * kthread_worker to avoid A-A deadlocks. 1645 */ 1646 kthread_queue_work(pwq_release_worker, &pwq->release_work); 1647 } 1648 1649 /** 1650 * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock 1651 * @pwq: pool_workqueue to put (can be %NULL) 1652 * 1653 * put_pwq() with locking. This function also allows %NULL @pwq. 1654 */ 1655 static void put_pwq_unlocked(struct pool_workqueue *pwq) 1656 { 1657 if (pwq) { 1658 /* 1659 * As both pwqs and pools are RCU protected, the 1660 * following lock operations are safe. 1661 */ 1662 raw_spin_lock_irq(&pwq->pool->lock); 1663 put_pwq(pwq); 1664 raw_spin_unlock_irq(&pwq->pool->lock); 1665 } 1666 } 1667 1668 static bool pwq_is_empty(struct pool_workqueue *pwq) 1669 { 1670 return !pwq->nr_active && list_empty(&pwq->inactive_works); 1671 } 1672 1673 static void __pwq_activate_work(struct pool_workqueue *pwq, 1674 struct work_struct *work) 1675 { 1676 unsigned long *wdb = work_data_bits(work); 1677 1678 WARN_ON_ONCE(!(*wdb & WORK_STRUCT_INACTIVE)); 1679 trace_workqueue_activate_work(work); 1680 if (list_empty(&pwq->pool->worklist)) 1681 pwq->pool->watchdog_ts = jiffies; 1682 move_linked_works(work, &pwq->pool->worklist, NULL); 1683 __clear_bit(WORK_STRUCT_INACTIVE_BIT, wdb); 1684 } 1685 1686 static bool tryinc_node_nr_active(struct wq_node_nr_active *nna) 1687 { 1688 int max = READ_ONCE(nna->max); 1689 1690 while (true) { 1691 int old, tmp; 1692 1693 old = atomic_read(&nna->nr); 1694 if (old >= max) 1695 return false; 1696 tmp = atomic_cmpxchg_relaxed(&nna->nr, old, old + 1); 1697 if (tmp == old) 1698 return true; 1699 } 1700 } 1701 1702 /** 1703 * pwq_tryinc_nr_active - Try to increment nr_active for a pwq 1704 * @pwq: pool_workqueue of interest 1705 * @fill: max_active may have increased, try to increase concurrency level 1706 * 1707 * Try to increment nr_active for @pwq. Returns %true if an nr_active count is 1708 * successfully obtained. %false otherwise. 1709 */ 1710 static bool pwq_tryinc_nr_active(struct pool_workqueue *pwq, bool fill) 1711 { 1712 struct workqueue_struct *wq = pwq->wq; 1713 struct worker_pool *pool = pwq->pool; 1714 struct wq_node_nr_active *nna = wq_node_nr_active(wq, pool->node); 1715 bool obtained = false; 1716 1717 lockdep_assert_held(&pool->lock); 1718 1719 if (!nna) { 1720 /* BH or per-cpu workqueue, pwq->nr_active is sufficient */ 1721 obtained = pwq->nr_active < READ_ONCE(wq->max_active); 1722 goto out; 1723 } 1724 1725 if (unlikely(pwq->plugged)) 1726 return false; 1727 1728 /* 1729 * Unbound workqueue uses per-node shared nr_active $nna. If @pwq is 1730 * already waiting on $nna, pwq_dec_nr_active() will maintain the 1731 * concurrency level. Don't jump the line. 1732 * 1733 * We need to ignore the pending test after max_active has increased as 1734 * pwq_dec_nr_active() can only maintain the concurrency level but not 1735 * increase it. This is indicated by @fill. 1736 */ 1737 if (!list_empty(&pwq->pending_node) && likely(!fill)) 1738 goto out; 1739 1740 obtained = tryinc_node_nr_active(nna); 1741 if (obtained) 1742 goto out; 1743 1744 /* 1745 * Lockless acquisition failed. Lock, add ourself to $nna->pending_pwqs 1746 * and try again. The smp_mb() is paired with the implied memory barrier 1747 * of atomic_dec_return() in pwq_dec_nr_active() to ensure that either 1748 * we see the decremented $nna->nr or they see non-empty 1749 * $nna->pending_pwqs. 1750 */ 1751 raw_spin_lock(&nna->lock); 1752 1753 if (list_empty(&pwq->pending_node)) 1754 list_add_tail(&pwq->pending_node, &nna->pending_pwqs); 1755 else if (likely(!fill)) 1756 goto out_unlock; 1757 1758 smp_mb(); 1759 1760 obtained = tryinc_node_nr_active(nna); 1761 1762 /* 1763 * If @fill, @pwq might have already been pending. Being spuriously 1764 * pending in cold paths doesn't affect anything. Let's leave it be. 1765 */ 1766 if (obtained && likely(!fill)) 1767 list_del_init(&pwq->pending_node); 1768 1769 out_unlock: 1770 raw_spin_unlock(&nna->lock); 1771 out: 1772 if (obtained) 1773 pwq->nr_active++; 1774 return obtained; 1775 } 1776 1777 /** 1778 * pwq_activate_first_inactive - Activate the first inactive work item on a pwq 1779 * @pwq: pool_workqueue of interest 1780 * @fill: max_active may have increased, try to increase concurrency level 1781 * 1782 * Activate the first inactive work item of @pwq if available and allowed by 1783 * max_active limit. 1784 * 1785 * Returns %true if an inactive work item has been activated. %false if no 1786 * inactive work item is found or max_active limit is reached. 1787 */ 1788 static bool pwq_activate_first_inactive(struct pool_workqueue *pwq, bool fill) 1789 { 1790 struct work_struct *work = 1791 list_first_entry_or_null(&pwq->inactive_works, 1792 struct work_struct, entry); 1793 1794 if (work && pwq_tryinc_nr_active(pwq, fill)) { 1795 __pwq_activate_work(pwq, work); 1796 return true; 1797 } else { 1798 return false; 1799 } 1800 } 1801 1802 /** 1803 * unplug_oldest_pwq - unplug the oldest pool_workqueue 1804 * @wq: workqueue_struct where its oldest pwq is to be unplugged 1805 * 1806 * This function should only be called for ordered workqueues where only the 1807 * oldest pwq is unplugged, the others are plugged to suspend execution to 1808 * ensure proper work item ordering:: 1809 * 1810 * dfl_pwq --------------+ [P] - plugged 1811 * | 1812 * v 1813 * pwqs -> A -> B [P] -> C [P] (newest) 1814 * | | | 1815 * 1 3 5 1816 * | | | 1817 * 2 4 6 1818 * 1819 * When the oldest pwq is drained and removed, this function should be called 1820 * to unplug the next oldest one to start its work item execution. Note that 1821 * pwq's are linked into wq->pwqs with the oldest first, so the first one in 1822 * the list is the oldest. 1823 */ 1824 static void unplug_oldest_pwq(struct workqueue_struct *wq) 1825 { 1826 struct pool_workqueue *pwq; 1827 1828 lockdep_assert_held(&wq->mutex); 1829 1830 /* Caller should make sure that pwqs isn't empty before calling */ 1831 pwq = list_first_entry_or_null(&wq->pwqs, struct pool_workqueue, 1832 pwqs_node); 1833 raw_spin_lock_irq(&pwq->pool->lock); 1834 if (pwq->plugged) { 1835 pwq->plugged = false; 1836 if (pwq_activate_first_inactive(pwq, true)) 1837 kick_pool(pwq->pool); 1838 } 1839 raw_spin_unlock_irq(&pwq->pool->lock); 1840 } 1841 1842 /** 1843 * node_activate_pending_pwq - Activate a pending pwq on a wq_node_nr_active 1844 * @nna: wq_node_nr_active to activate a pending pwq for 1845 * @caller_pool: worker_pool the caller is locking 1846 * 1847 * Activate a pwq in @nna->pending_pwqs. Called with @caller_pool locked. 1848 * @caller_pool may be unlocked and relocked to lock other worker_pools. 1849 */ 1850 static void node_activate_pending_pwq(struct wq_node_nr_active *nna, 1851 struct worker_pool *caller_pool) 1852 { 1853 struct worker_pool *locked_pool = caller_pool; 1854 struct pool_workqueue *pwq; 1855 struct work_struct *work; 1856 1857 lockdep_assert_held(&caller_pool->lock); 1858 1859 raw_spin_lock(&nna->lock); 1860 retry: 1861 pwq = list_first_entry_or_null(&nna->pending_pwqs, 1862 struct pool_workqueue, pending_node); 1863 if (!pwq) 1864 goto out_unlock; 1865 1866 /* 1867 * If @pwq is for a different pool than @locked_pool, we need to lock 1868 * @pwq->pool->lock. Let's trylock first. If unsuccessful, do the unlock 1869 * / lock dance. For that, we also need to release @nna->lock as it's 1870 * nested inside pool locks. 1871 */ 1872 if (pwq->pool != locked_pool) { 1873 raw_spin_unlock(&locked_pool->lock); 1874 locked_pool = pwq->pool; 1875 if (!raw_spin_trylock(&locked_pool->lock)) { 1876 raw_spin_unlock(&nna->lock); 1877 raw_spin_lock(&locked_pool->lock); 1878 raw_spin_lock(&nna->lock); 1879 goto retry; 1880 } 1881 } 1882 1883 /* 1884 * $pwq may not have any inactive work items due to e.g. cancellations. 1885 * Drop it from pending_pwqs and see if there's another one. 1886 */ 1887 work = list_first_entry_or_null(&pwq->inactive_works, 1888 struct work_struct, entry); 1889 if (!work) { 1890 list_del_init(&pwq->pending_node); 1891 goto retry; 1892 } 1893 1894 /* 1895 * Acquire an nr_active count and activate the inactive work item. If 1896 * $pwq still has inactive work items, rotate it to the end of the 1897 * pending_pwqs so that we round-robin through them. This means that 1898 * inactive work items are not activated in queueing order which is fine 1899 * given that there has never been any ordering across different pwqs. 1900 */ 1901 if (likely(tryinc_node_nr_active(nna))) { 1902 pwq->nr_active++; 1903 __pwq_activate_work(pwq, work); 1904 1905 if (list_empty(&pwq->inactive_works)) 1906 list_del_init(&pwq->pending_node); 1907 else 1908 list_move_tail(&pwq->pending_node, &nna->pending_pwqs); 1909 1910 /* if activating a foreign pool, make sure it's running */ 1911 if (pwq->pool != caller_pool) 1912 kick_pool(pwq->pool); 1913 } 1914 1915 out_unlock: 1916 raw_spin_unlock(&nna->lock); 1917 if (locked_pool != caller_pool) { 1918 raw_spin_unlock(&locked_pool->lock); 1919 raw_spin_lock(&caller_pool->lock); 1920 } 1921 } 1922 1923 /** 1924 * pwq_dec_nr_active - Retire an active count 1925 * @pwq: pool_workqueue of interest 1926 * 1927 * Decrement @pwq's nr_active and try to activate the first inactive work item. 1928 * For unbound workqueues, this function may temporarily drop @pwq->pool->lock. 1929 */ 1930 static void pwq_dec_nr_active(struct pool_workqueue *pwq) 1931 { 1932 struct worker_pool *pool = pwq->pool; 1933 struct wq_node_nr_active *nna = wq_node_nr_active(pwq->wq, pool->node); 1934 1935 lockdep_assert_held(&pool->lock); 1936 1937 /* 1938 * @pwq->nr_active should be decremented for both percpu and unbound 1939 * workqueues. 1940 */ 1941 pwq->nr_active--; 1942 1943 /* 1944 * For a percpu workqueue, it's simple. Just need to kick the first 1945 * inactive work item on @pwq itself. 1946 */ 1947 if (!nna) { 1948 pwq_activate_first_inactive(pwq, false); 1949 return; 1950 } 1951 1952 /* 1953 * If @pwq is for an unbound workqueue, it's more complicated because 1954 * multiple pwqs and pools may be sharing the nr_active count. When a 1955 * pwq needs to wait for an nr_active count, it puts itself on 1956 * $nna->pending_pwqs. The following atomic_dec_return()'s implied 1957 * memory barrier is paired with smp_mb() in pwq_tryinc_nr_active() to 1958 * guarantee that either we see non-empty pending_pwqs or they see 1959 * decremented $nna->nr. 1960 * 1961 * $nna->max may change as CPUs come online/offline and @pwq->wq's 1962 * max_active gets updated. However, it is guaranteed to be equal to or 1963 * larger than @pwq->wq->min_active which is above zero unless freezing. 1964 * This maintains the forward progress guarantee. 1965 */ 1966 if (atomic_dec_return(&nna->nr) >= READ_ONCE(nna->max)) 1967 return; 1968 1969 if (!list_empty(&nna->pending_pwqs)) 1970 node_activate_pending_pwq(nna, pool); 1971 } 1972 1973 /** 1974 * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight 1975 * @pwq: pwq of interest 1976 * @work_data: work_data of work which left the queue 1977 * 1978 * A work either has completed or is removed from pending queue, 1979 * decrement nr_in_flight of its pwq and handle workqueue flushing. 1980 * 1981 * NOTE: 1982 * For unbound workqueues, this function may temporarily drop @pwq->pool->lock 1983 * and thus should be called after all other state updates for the in-flight 1984 * work item is complete. 1985 * 1986 * CONTEXT: 1987 * raw_spin_lock_irq(pool->lock). 1988 */ 1989 static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, unsigned long work_data) 1990 { 1991 int color = get_work_color(work_data); 1992 1993 if (!(work_data & WORK_STRUCT_INACTIVE)) 1994 pwq_dec_nr_active(pwq); 1995 1996 pwq->nr_in_flight[color]--; 1997 1998 /* is flush in progress and are we at the flushing tip? */ 1999 if (likely(pwq->flush_color != color)) 2000 goto out_put; 2001 2002 /* are there still in-flight works? */ 2003 if (pwq->nr_in_flight[color]) 2004 goto out_put; 2005 2006 /* this pwq is done, clear flush_color */ 2007 pwq->flush_color = -1; 2008 2009 /* 2010 * If this was the last pwq, wake up the first flusher. It 2011 * will handle the rest. 2012 */ 2013 if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush)) 2014 complete(&pwq->wq->first_flusher->done); 2015 out_put: 2016 put_pwq(pwq); 2017 } 2018 2019 /** 2020 * try_to_grab_pending - steal work item from worklist and disable irq 2021 * @work: work item to steal 2022 * @cflags: %WORK_CANCEL_ flags 2023 * @irq_flags: place to store irq state 2024 * 2025 * Try to grab PENDING bit of @work. This function can handle @work in any 2026 * stable state - idle, on timer or on worklist. 2027 * 2028 * Return: 2029 * 2030 * ======== ================================================================ 2031 * 1 if @work was pending and we successfully stole PENDING 2032 * 0 if @work was idle and we claimed PENDING 2033 * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry 2034 * ======== ================================================================ 2035 * 2036 * Note: 2037 * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting 2038 * interrupted while holding PENDING and @work off queue, irq must be 2039 * disabled on entry. This, combined with delayed_work->timer being 2040 * irqsafe, ensures that we return -EAGAIN for finite short period of time. 2041 * 2042 * On successful return, >= 0, irq is disabled and the caller is 2043 * responsible for releasing it using local_irq_restore(*@irq_flags). 2044 * 2045 * This function is safe to call from any context including IRQ handler. 2046 */ 2047 static int try_to_grab_pending(struct work_struct *work, u32 cflags, 2048 unsigned long *irq_flags) 2049 { 2050 struct worker_pool *pool; 2051 struct pool_workqueue *pwq; 2052 2053 local_irq_save(*irq_flags); 2054 2055 /* try to steal the timer if it exists */ 2056 if (cflags & WORK_CANCEL_DELAYED) { 2057 struct delayed_work *dwork = to_delayed_work(work); 2058 2059 /* 2060 * dwork->timer is irqsafe. If del_timer() fails, it's 2061 * guaranteed that the timer is not queued anywhere and not 2062 * running on the local CPU. 2063 */ 2064 if (likely(del_timer(&dwork->timer))) 2065 return 1; 2066 } 2067 2068 /* try to claim PENDING the normal way */ 2069 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) 2070 return 0; 2071 2072 rcu_read_lock(); 2073 /* 2074 * The queueing is in progress, or it is already queued. Try to 2075 * steal it from ->worklist without clearing WORK_STRUCT_PENDING. 2076 */ 2077 pool = get_work_pool(work); 2078 if (!pool) 2079 goto fail; 2080 2081 raw_spin_lock(&pool->lock); 2082 /* 2083 * work->data is guaranteed to point to pwq only while the work 2084 * item is queued on pwq->wq, and both updating work->data to point 2085 * to pwq on queueing and to pool on dequeueing are done under 2086 * pwq->pool->lock. This in turn guarantees that, if work->data 2087 * points to pwq which is associated with a locked pool, the work 2088 * item is currently queued on that pool. 2089 */ 2090 pwq = get_work_pwq(work); 2091 if (pwq && pwq->pool == pool) { 2092 unsigned long work_data = *work_data_bits(work); 2093 2094 debug_work_deactivate(work); 2095 2096 /* 2097 * A cancelable inactive work item must be in the 2098 * pwq->inactive_works since a queued barrier can't be 2099 * canceled (see the comments in insert_wq_barrier()). 2100 * 2101 * An inactive work item cannot be deleted directly because 2102 * it might have linked barrier work items which, if left 2103 * on the inactive_works list, will confuse pwq->nr_active 2104 * management later on and cause stall. Move the linked 2105 * barrier work items to the worklist when deleting the grabbed 2106 * item. Also keep WORK_STRUCT_INACTIVE in work_data, so that 2107 * it doesn't participate in nr_active management in later 2108 * pwq_dec_nr_in_flight(). 2109 */ 2110 if (work_data & WORK_STRUCT_INACTIVE) 2111 move_linked_works(work, &pwq->pool->worklist, NULL); 2112 2113 list_del_init(&work->entry); 2114 2115 /* 2116 * work->data points to pwq iff queued. Let's point to pool. As 2117 * this destroys work->data needed by the next step, stash it. 2118 */ 2119 set_work_pool_and_keep_pending(work, pool->id, 2120 pool_offq_flags(pool)); 2121 2122 /* must be the last step, see the function comment */ 2123 pwq_dec_nr_in_flight(pwq, work_data); 2124 2125 raw_spin_unlock(&pool->lock); 2126 rcu_read_unlock(); 2127 return 1; 2128 } 2129 raw_spin_unlock(&pool->lock); 2130 fail: 2131 rcu_read_unlock(); 2132 local_irq_restore(*irq_flags); 2133 return -EAGAIN; 2134 } 2135 2136 /** 2137 * work_grab_pending - steal work item from worklist and disable irq 2138 * @work: work item to steal 2139 * @cflags: %WORK_CANCEL_ flags 2140 * @irq_flags: place to store IRQ state 2141 * 2142 * Grab PENDING bit of @work. @work can be in any stable state - idle, on timer 2143 * or on worklist. 2144 * 2145 * Can be called from any context. IRQ is disabled on return with IRQ state 2146 * stored in *@irq_flags. The caller is responsible for re-enabling it using 2147 * local_irq_restore(). 2148 * 2149 * Returns %true if @work was pending. %false if idle. 2150 */ 2151 static bool work_grab_pending(struct work_struct *work, u32 cflags, 2152 unsigned long *irq_flags) 2153 { 2154 int ret; 2155 2156 while (true) { 2157 ret = try_to_grab_pending(work, cflags, irq_flags); 2158 if (ret >= 0) 2159 return ret; 2160 cpu_relax(); 2161 } 2162 } 2163 2164 /** 2165 * insert_work - insert a work into a pool 2166 * @pwq: pwq @work belongs to 2167 * @work: work to insert 2168 * @head: insertion point 2169 * @extra_flags: extra WORK_STRUCT_* flags to set 2170 * 2171 * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to 2172 * work_struct flags. 2173 * 2174 * CONTEXT: 2175 * raw_spin_lock_irq(pool->lock). 2176 */ 2177 static void insert_work(struct pool_workqueue *pwq, struct work_struct *work, 2178 struct list_head *head, unsigned int extra_flags) 2179 { 2180 debug_work_activate(work); 2181 2182 /* record the work call stack in order to print it in KASAN reports */ 2183 kasan_record_aux_stack_noalloc(work); 2184 2185 /* we own @work, set data and link */ 2186 set_work_pwq(work, pwq, extra_flags); 2187 list_add_tail(&work->entry, head); 2188 get_pwq(pwq); 2189 } 2190 2191 /* 2192 * Test whether @work is being queued from another work executing on the 2193 * same workqueue. 2194 */ 2195 static bool is_chained_work(struct workqueue_struct *wq) 2196 { 2197 struct worker *worker; 2198 2199 worker = current_wq_worker(); 2200 /* 2201 * Return %true iff I'm a worker executing a work item on @wq. If 2202 * I'm @worker, it's safe to dereference it without locking. 2203 */ 2204 return worker && worker->current_pwq->wq == wq; 2205 } 2206 2207 /* 2208 * When queueing an unbound work item to a wq, prefer local CPU if allowed 2209 * by wq_unbound_cpumask. Otherwise, round robin among the allowed ones to 2210 * avoid perturbing sensitive tasks. 2211 */ 2212 static int wq_select_unbound_cpu(int cpu) 2213 { 2214 int new_cpu; 2215 2216 if (likely(!wq_debug_force_rr_cpu)) { 2217 if (cpumask_test_cpu(cpu, wq_unbound_cpumask)) 2218 return cpu; 2219 } else { 2220 pr_warn_once("workqueue: round-robin CPU selection forced, expect performance impact\n"); 2221 } 2222 2223 new_cpu = __this_cpu_read(wq_rr_cpu_last); 2224 new_cpu = cpumask_next_and(new_cpu, wq_unbound_cpumask, cpu_online_mask); 2225 if (unlikely(new_cpu >= nr_cpu_ids)) { 2226 new_cpu = cpumask_first_and(wq_unbound_cpumask, cpu_online_mask); 2227 if (unlikely(new_cpu >= nr_cpu_ids)) 2228 return cpu; 2229 } 2230 __this_cpu_write(wq_rr_cpu_last, new_cpu); 2231 2232 return new_cpu; 2233 } 2234 2235 static void __queue_work(int cpu, struct workqueue_struct *wq, 2236 struct work_struct *work) 2237 { 2238 struct pool_workqueue *pwq; 2239 struct worker_pool *last_pool, *pool; 2240 unsigned int work_flags; 2241 unsigned int req_cpu = cpu; 2242 2243 /* 2244 * While a work item is PENDING && off queue, a task trying to 2245 * steal the PENDING will busy-loop waiting for it to either get 2246 * queued or lose PENDING. Grabbing PENDING and queueing should 2247 * happen with IRQ disabled. 2248 */ 2249 lockdep_assert_irqs_disabled(); 2250 2251 /* 2252 * For a draining wq, only works from the same workqueue are 2253 * allowed. The __WQ_DESTROYING helps to spot the issue that 2254 * queues a new work item to a wq after destroy_workqueue(wq). 2255 */ 2256 if (unlikely(wq->flags & (__WQ_DESTROYING | __WQ_DRAINING) && 2257 WARN_ON_ONCE(!is_chained_work(wq)))) 2258 return; 2259 rcu_read_lock(); 2260 retry: 2261 /* pwq which will be used unless @work is executing elsewhere */ 2262 if (req_cpu == WORK_CPU_UNBOUND) { 2263 if (wq->flags & WQ_UNBOUND) 2264 cpu = wq_select_unbound_cpu(raw_smp_processor_id()); 2265 else 2266 cpu = raw_smp_processor_id(); 2267 } 2268 2269 pwq = rcu_dereference(*per_cpu_ptr(wq->cpu_pwq, cpu)); 2270 pool = pwq->pool; 2271 2272 /* 2273 * If @work was previously on a different pool, it might still be 2274 * running there, in which case the work needs to be queued on that 2275 * pool to guarantee non-reentrancy. 2276 * 2277 * For ordered workqueue, work items must be queued on the newest pwq 2278 * for accurate order management. Guaranteed order also guarantees 2279 * non-reentrancy. See the comments above unplug_oldest_pwq(). 2280 */ 2281 last_pool = get_work_pool(work); 2282 if (last_pool && last_pool != pool && !(wq->flags & __WQ_ORDERED)) { 2283 struct worker *worker; 2284 2285 raw_spin_lock(&last_pool->lock); 2286 2287 worker = find_worker_executing_work(last_pool, work); 2288 2289 if (worker && worker->current_pwq->wq == wq) { 2290 pwq = worker->current_pwq; 2291 pool = pwq->pool; 2292 WARN_ON_ONCE(pool != last_pool); 2293 } else { 2294 /* meh... not running there, queue here */ 2295 raw_spin_unlock(&last_pool->lock); 2296 raw_spin_lock(&pool->lock); 2297 } 2298 } else { 2299 raw_spin_lock(&pool->lock); 2300 } 2301 2302 /* 2303 * pwq is determined and locked. For unbound pools, we could have raced 2304 * with pwq release and it could already be dead. If its refcnt is zero, 2305 * repeat pwq selection. Note that unbound pwqs never die without 2306 * another pwq replacing it in cpu_pwq or while work items are executing 2307 * on it, so the retrying is guaranteed to make forward-progress. 2308 */ 2309 if (unlikely(!pwq->refcnt)) { 2310 if (wq->flags & WQ_UNBOUND) { 2311 raw_spin_unlock(&pool->lock); 2312 cpu_relax(); 2313 goto retry; 2314 } 2315 /* oops */ 2316 WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt", 2317 wq->name, cpu); 2318 } 2319 2320 /* pwq determined, queue */ 2321 trace_workqueue_queue_work(req_cpu, pwq, work); 2322 2323 if (WARN_ON(!list_empty(&work->entry))) 2324 goto out; 2325 2326 pwq->nr_in_flight[pwq->work_color]++; 2327 work_flags = work_color_to_flags(pwq->work_color); 2328 2329 /* 2330 * Limit the number of concurrently active work items to max_active. 2331 * @work must also queue behind existing inactive work items to maintain 2332 * ordering when max_active changes. See wq_adjust_max_active(). 2333 */ 2334 if (list_empty(&pwq->inactive_works) && pwq_tryinc_nr_active(pwq, false)) { 2335 if (list_empty(&pool->worklist)) 2336 pool->watchdog_ts = jiffies; 2337 2338 trace_workqueue_activate_work(work); 2339 insert_work(pwq, work, &pool->worklist, work_flags); 2340 kick_pool(pool); 2341 } else { 2342 work_flags |= WORK_STRUCT_INACTIVE; 2343 insert_work(pwq, work, &pwq->inactive_works, work_flags); 2344 } 2345 2346 out: 2347 raw_spin_unlock(&pool->lock); 2348 rcu_read_unlock(); 2349 } 2350 2351 static bool clear_pending_if_disabled(struct work_struct *work) 2352 { 2353 unsigned long data = *work_data_bits(work); 2354 struct work_offq_data offqd; 2355 2356 if (likely((data & WORK_STRUCT_PWQ) || 2357 !(data & WORK_OFFQ_DISABLE_MASK))) 2358 return false; 2359 2360 work_offqd_unpack(&offqd, data); 2361 set_work_pool_and_clear_pending(work, offqd.pool_id, 2362 work_offqd_pack_flags(&offqd)); 2363 return true; 2364 } 2365 2366 /** 2367 * queue_work_on - queue work on specific cpu 2368 * @cpu: CPU number to execute work on 2369 * @wq: workqueue to use 2370 * @work: work to queue 2371 * 2372 * We queue the work to a specific CPU, the caller must ensure it 2373 * can't go away. Callers that fail to ensure that the specified 2374 * CPU cannot go away will execute on a randomly chosen CPU. 2375 * But note well that callers specifying a CPU that never has been 2376 * online will get a splat. 2377 * 2378 * Return: %false if @work was already on a queue, %true otherwise. 2379 */ 2380 bool queue_work_on(int cpu, struct workqueue_struct *wq, 2381 struct work_struct *work) 2382 { 2383 bool ret = false; 2384 unsigned long irq_flags; 2385 2386 local_irq_save(irq_flags); 2387 2388 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)) && 2389 !clear_pending_if_disabled(work)) { 2390 __queue_work(cpu, wq, work); 2391 ret = true; 2392 } 2393 2394 local_irq_restore(irq_flags); 2395 return ret; 2396 } 2397 EXPORT_SYMBOL(queue_work_on); 2398 2399 /** 2400 * select_numa_node_cpu - Select a CPU based on NUMA node 2401 * @node: NUMA node ID that we want to select a CPU from 2402 * 2403 * This function will attempt to find a "random" cpu available on a given 2404 * node. If there are no CPUs available on the given node it will return 2405 * WORK_CPU_UNBOUND indicating that we should just schedule to any 2406 * available CPU if we need to schedule this work. 2407 */ 2408 static int select_numa_node_cpu(int node) 2409 { 2410 int cpu; 2411 2412 /* Delay binding to CPU if node is not valid or online */ 2413 if (node < 0 || node >= MAX_NUMNODES || !node_online(node)) 2414 return WORK_CPU_UNBOUND; 2415 2416 /* Use local node/cpu if we are already there */ 2417 cpu = raw_smp_processor_id(); 2418 if (node == cpu_to_node(cpu)) 2419 return cpu; 2420 2421 /* Use "random" otherwise know as "first" online CPU of node */ 2422 cpu = cpumask_any_and(cpumask_of_node(node), cpu_online_mask); 2423 2424 /* If CPU is valid return that, otherwise just defer */ 2425 return cpu < nr_cpu_ids ? cpu : WORK_CPU_UNBOUND; 2426 } 2427 2428 /** 2429 * queue_work_node - queue work on a "random" cpu for a given NUMA node 2430 * @node: NUMA node that we are targeting the work for 2431 * @wq: workqueue to use 2432 * @work: work to queue 2433 * 2434 * We queue the work to a "random" CPU within a given NUMA node. The basic 2435 * idea here is to provide a way to somehow associate work with a given 2436 * NUMA node. 2437 * 2438 * This function will only make a best effort attempt at getting this onto 2439 * the right NUMA node. If no node is requested or the requested node is 2440 * offline then we just fall back to standard queue_work behavior. 2441 * 2442 * Currently the "random" CPU ends up being the first available CPU in the 2443 * intersection of cpu_online_mask and the cpumask of the node, unless we 2444 * are running on the node. In that case we just use the current CPU. 2445 * 2446 * Return: %false if @work was already on a queue, %true otherwise. 2447 */ 2448 bool queue_work_node(int node, struct workqueue_struct *wq, 2449 struct work_struct *work) 2450 { 2451 unsigned long irq_flags; 2452 bool ret = false; 2453 2454 /* 2455 * This current implementation is specific to unbound workqueues. 2456 * Specifically we only return the first available CPU for a given 2457 * node instead of cycling through individual CPUs within the node. 2458 * 2459 * If this is used with a per-cpu workqueue then the logic in 2460 * workqueue_select_cpu_near would need to be updated to allow for 2461 * some round robin type logic. 2462 */ 2463 WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)); 2464 2465 local_irq_save(irq_flags); 2466 2467 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)) && 2468 !clear_pending_if_disabled(work)) { 2469 int cpu = select_numa_node_cpu(node); 2470 2471 __queue_work(cpu, wq, work); 2472 ret = true; 2473 } 2474 2475 local_irq_restore(irq_flags); 2476 return ret; 2477 } 2478 EXPORT_SYMBOL_GPL(queue_work_node); 2479 2480 void delayed_work_timer_fn(struct timer_list *t) 2481 { 2482 struct delayed_work *dwork = from_timer(dwork, t, timer); 2483 2484 /* should have been called from irqsafe timer with irq already off */ 2485 __queue_work(dwork->cpu, dwork->wq, &dwork->work); 2486 } 2487 EXPORT_SYMBOL(delayed_work_timer_fn); 2488 2489 static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, 2490 struct delayed_work *dwork, unsigned long delay) 2491 { 2492 struct timer_list *timer = &dwork->timer; 2493 struct work_struct *work = &dwork->work; 2494 2495 WARN_ON_ONCE(!wq); 2496 WARN_ON_ONCE(timer->function != delayed_work_timer_fn); 2497 WARN_ON_ONCE(timer_pending(timer)); 2498 WARN_ON_ONCE(!list_empty(&work->entry)); 2499 2500 /* 2501 * If @delay is 0, queue @dwork->work immediately. This is for 2502 * both optimization and correctness. The earliest @timer can 2503 * expire is on the closest next tick and delayed_work users depend 2504 * on that there's no such delay when @delay is 0. 2505 */ 2506 if (!delay) { 2507 __queue_work(cpu, wq, &dwork->work); 2508 return; 2509 } 2510 2511 dwork->wq = wq; 2512 dwork->cpu = cpu; 2513 timer->expires = jiffies + delay; 2514 2515 if (housekeeping_enabled(HK_TYPE_TIMER)) { 2516 /* If the current cpu is a housekeeping cpu, use it. */ 2517 cpu = smp_processor_id(); 2518 if (!housekeeping_test_cpu(cpu, HK_TYPE_TIMER)) 2519 cpu = housekeeping_any_cpu(HK_TYPE_TIMER); 2520 add_timer_on(timer, cpu); 2521 } else { 2522 if (likely(cpu == WORK_CPU_UNBOUND)) 2523 add_timer_global(timer); 2524 else 2525 add_timer_on(timer, cpu); 2526 } 2527 } 2528 2529 /** 2530 * queue_delayed_work_on - queue work on specific CPU after delay 2531 * @cpu: CPU number to execute work on 2532 * @wq: workqueue to use 2533 * @dwork: work to queue 2534 * @delay: number of jiffies to wait before queueing 2535 * 2536 * Return: %false if @work was already on a queue, %true otherwise. If 2537 * @delay is zero and @dwork is idle, it will be scheduled for immediate 2538 * execution. 2539 */ 2540 bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, 2541 struct delayed_work *dwork, unsigned long delay) 2542 { 2543 struct work_struct *work = &dwork->work; 2544 bool ret = false; 2545 unsigned long irq_flags; 2546 2547 /* read the comment in __queue_work() */ 2548 local_irq_save(irq_flags); 2549 2550 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)) && 2551 !clear_pending_if_disabled(work)) { 2552 __queue_delayed_work(cpu, wq, dwork, delay); 2553 ret = true; 2554 } 2555 2556 local_irq_restore(irq_flags); 2557 return ret; 2558 } 2559 EXPORT_SYMBOL(queue_delayed_work_on); 2560 2561 /** 2562 * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU 2563 * @cpu: CPU number to execute work on 2564 * @wq: workqueue to use 2565 * @dwork: work to queue 2566 * @delay: number of jiffies to wait before queueing 2567 * 2568 * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise, 2569 * modify @dwork's timer so that it expires after @delay. If @delay is 2570 * zero, @work is guaranteed to be scheduled immediately regardless of its 2571 * current state. 2572 * 2573 * Return: %false if @dwork was idle and queued, %true if @dwork was 2574 * pending and its timer was modified. 2575 * 2576 * This function is safe to call from any context including IRQ handler. 2577 * See try_to_grab_pending() for details. 2578 */ 2579 bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, 2580 struct delayed_work *dwork, unsigned long delay) 2581 { 2582 unsigned long irq_flags; 2583 bool ret; 2584 2585 ret = work_grab_pending(&dwork->work, WORK_CANCEL_DELAYED, &irq_flags); 2586 2587 if (!clear_pending_if_disabled(&dwork->work)) 2588 __queue_delayed_work(cpu, wq, dwork, delay); 2589 2590 local_irq_restore(irq_flags); 2591 return ret; 2592 } 2593 EXPORT_SYMBOL_GPL(mod_delayed_work_on); 2594 2595 static void rcu_work_rcufn(struct rcu_head *rcu) 2596 { 2597 struct rcu_work *rwork = container_of(rcu, struct rcu_work, rcu); 2598 2599 /* read the comment in __queue_work() */ 2600 local_irq_disable(); 2601 __queue_work(WORK_CPU_UNBOUND, rwork->wq, &rwork->work); 2602 local_irq_enable(); 2603 } 2604 2605 /** 2606 * queue_rcu_work - queue work after a RCU grace period 2607 * @wq: workqueue to use 2608 * @rwork: work to queue 2609 * 2610 * Return: %false if @rwork was already pending, %true otherwise. Note 2611 * that a full RCU grace period is guaranteed only after a %true return. 2612 * While @rwork is guaranteed to be executed after a %false return, the 2613 * execution may happen before a full RCU grace period has passed. 2614 */ 2615 bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork) 2616 { 2617 struct work_struct *work = &rwork->work; 2618 2619 /* 2620 * rcu_work can't be canceled or disabled. Warn if the user reached 2621 * inside @rwork and disabled the inner work. 2622 */ 2623 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)) && 2624 !WARN_ON_ONCE(clear_pending_if_disabled(work))) { 2625 rwork->wq = wq; 2626 call_rcu_hurry(&rwork->rcu, rcu_work_rcufn); 2627 return true; 2628 } 2629 2630 return false; 2631 } 2632 EXPORT_SYMBOL(queue_rcu_work); 2633 2634 static struct worker *alloc_worker(int node) 2635 { 2636 struct worker *worker; 2637 2638 worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, node); 2639 if (worker) { 2640 INIT_LIST_HEAD(&worker->entry); 2641 INIT_LIST_HEAD(&worker->scheduled); 2642 INIT_LIST_HEAD(&worker->node); 2643 /* on creation a worker is in !idle && prep state */ 2644 worker->flags = WORKER_PREP; 2645 } 2646 return worker; 2647 } 2648 2649 static cpumask_t *pool_allowed_cpus(struct worker_pool *pool) 2650 { 2651 if (pool->cpu < 0 && pool->attrs->affn_strict) 2652 return pool->attrs->__pod_cpumask; 2653 else 2654 return pool->attrs->cpumask; 2655 } 2656 2657 /** 2658 * worker_attach_to_pool() - attach a worker to a pool 2659 * @worker: worker to be attached 2660 * @pool: the target pool 2661 * 2662 * Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and 2663 * cpu-binding of @worker are kept coordinated with the pool across 2664 * cpu-[un]hotplugs. 2665 */ 2666 static void worker_attach_to_pool(struct worker *worker, 2667 struct worker_pool *pool) 2668 { 2669 mutex_lock(&wq_pool_attach_mutex); 2670 2671 /* 2672 * The wq_pool_attach_mutex ensures %POOL_DISASSOCIATED remains stable 2673 * across this function. See the comments above the flag definition for 2674 * details. BH workers are, while per-CPU, always DISASSOCIATED. 2675 */ 2676 if (pool->flags & POOL_DISASSOCIATED) { 2677 worker->flags |= WORKER_UNBOUND; 2678 } else { 2679 WARN_ON_ONCE(pool->flags & POOL_BH); 2680 kthread_set_per_cpu(worker->task, pool->cpu); 2681 } 2682 2683 if (worker->rescue_wq) 2684 set_cpus_allowed_ptr(worker->task, pool_allowed_cpus(pool)); 2685 2686 list_add_tail(&worker->node, &pool->workers); 2687 worker->pool = pool; 2688 2689 mutex_unlock(&wq_pool_attach_mutex); 2690 } 2691 2692 static void unbind_worker(struct worker *worker) 2693 { 2694 lockdep_assert_held(&wq_pool_attach_mutex); 2695 2696 kthread_set_per_cpu(worker->task, -1); 2697 if (cpumask_intersects(wq_unbound_cpumask, cpu_active_mask)) 2698 WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, wq_unbound_cpumask) < 0); 2699 else 2700 WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0); 2701 } 2702 2703 2704 static void detach_worker(struct worker *worker) 2705 { 2706 lockdep_assert_held(&wq_pool_attach_mutex); 2707 2708 unbind_worker(worker); 2709 list_del(&worker->node); 2710 } 2711 2712 /** 2713 * worker_detach_from_pool() - detach a worker from its pool 2714 * @worker: worker which is attached to its pool 2715 * 2716 * Undo the attaching which had been done in worker_attach_to_pool(). The 2717 * caller worker shouldn't access to the pool after detached except it has 2718 * other reference to the pool. 2719 */ 2720 static void worker_detach_from_pool(struct worker *worker) 2721 { 2722 struct worker_pool *pool = worker->pool; 2723 2724 /* there is one permanent BH worker per CPU which should never detach */ 2725 WARN_ON_ONCE(pool->flags & POOL_BH); 2726 2727 mutex_lock(&wq_pool_attach_mutex); 2728 detach_worker(worker); 2729 worker->pool = NULL; 2730 mutex_unlock(&wq_pool_attach_mutex); 2731 2732 /* clear leftover flags without pool->lock after it is detached */ 2733 worker->flags &= ~(WORKER_UNBOUND | WORKER_REBOUND); 2734 } 2735 2736 static int format_worker_id(char *buf, size_t size, struct worker *worker, 2737 struct worker_pool *pool) 2738 { 2739 if (worker->rescue_wq) 2740 return scnprintf(buf, size, "kworker/R-%s", 2741 worker->rescue_wq->name); 2742 2743 if (pool) { 2744 if (pool->cpu >= 0) 2745 return scnprintf(buf, size, "kworker/%d:%d%s", 2746 pool->cpu, worker->id, 2747 pool->attrs->nice < 0 ? "H" : ""); 2748 else 2749 return scnprintf(buf, size, "kworker/u%d:%d", 2750 pool->id, worker->id); 2751 } else { 2752 return scnprintf(buf, size, "kworker/dying"); 2753 } 2754 } 2755 2756 /** 2757 * create_worker - create a new workqueue worker 2758 * @pool: pool the new worker will belong to 2759 * 2760 * Create and start a new worker which is attached to @pool. 2761 * 2762 * CONTEXT: 2763 * Might sleep. Does GFP_KERNEL allocations. 2764 * 2765 * Return: 2766 * Pointer to the newly created worker. 2767 */ 2768 static struct worker *create_worker(struct worker_pool *pool) 2769 { 2770 struct worker *worker; 2771 int id; 2772 2773 /* ID is needed to determine kthread name */ 2774 id = ida_alloc(&pool->worker_ida, GFP_KERNEL); 2775 if (id < 0) { 2776 pr_err_once("workqueue: Failed to allocate a worker ID: %pe\n", 2777 ERR_PTR(id)); 2778 return NULL; 2779 } 2780 2781 worker = alloc_worker(pool->node); 2782 if (!worker) { 2783 pr_err_once("workqueue: Failed to allocate a worker\n"); 2784 goto fail; 2785 } 2786 2787 worker->id = id; 2788 2789 if (!(pool->flags & POOL_BH)) { 2790 char id_buf[WORKER_ID_LEN]; 2791 2792 format_worker_id(id_buf, sizeof(id_buf), worker, pool); 2793 worker->task = kthread_create_on_node(worker_thread, worker, 2794 pool->node, "%s", id_buf); 2795 if (IS_ERR(worker->task)) { 2796 if (PTR_ERR(worker->task) == -EINTR) { 2797 pr_err("workqueue: Interrupted when creating a worker thread \"%s\"\n", 2798 id_buf); 2799 } else { 2800 pr_err_once("workqueue: Failed to create a worker thread: %pe", 2801 worker->task); 2802 } 2803 goto fail; 2804 } 2805 2806 set_user_nice(worker->task, pool->attrs->nice); 2807 kthread_bind_mask(worker->task, pool_allowed_cpus(pool)); 2808 } 2809 2810 /* successful, attach the worker to the pool */ 2811 worker_attach_to_pool(worker, pool); 2812 2813 /* start the newly created worker */ 2814 raw_spin_lock_irq(&pool->lock); 2815 2816 worker->pool->nr_workers++; 2817 worker_enter_idle(worker); 2818 2819 /* 2820 * @worker is waiting on a completion in kthread() and will trigger hung 2821 * check if not woken up soon. As kick_pool() is noop if @pool is empty, 2822 * wake it up explicitly. 2823 */ 2824 if (worker->task) 2825 wake_up_process(worker->task); 2826 2827 raw_spin_unlock_irq(&pool->lock); 2828 2829 return worker; 2830 2831 fail: 2832 ida_free(&pool->worker_ida, id); 2833 kfree(worker); 2834 return NULL; 2835 } 2836 2837 static void detach_dying_workers(struct list_head *cull_list) 2838 { 2839 struct worker *worker; 2840 2841 list_for_each_entry(worker, cull_list, entry) 2842 detach_worker(worker); 2843 } 2844 2845 static void reap_dying_workers(struct list_head *cull_list) 2846 { 2847 struct worker *worker, *tmp; 2848 2849 list_for_each_entry_safe(worker, tmp, cull_list, entry) { 2850 list_del_init(&worker->entry); 2851 kthread_stop_put(worker->task); 2852 kfree(worker); 2853 } 2854 } 2855 2856 /** 2857 * set_worker_dying - Tag a worker for destruction 2858 * @worker: worker to be destroyed 2859 * @list: transfer worker away from its pool->idle_list and into list 2860 * 2861 * Tag @worker for destruction and adjust @pool stats accordingly. The worker 2862 * should be idle. 2863 * 2864 * CONTEXT: 2865 * raw_spin_lock_irq(pool->lock). 2866 */ 2867 static void set_worker_dying(struct worker *worker, struct list_head *list) 2868 { 2869 struct worker_pool *pool = worker->pool; 2870 2871 lockdep_assert_held(&pool->lock); 2872 lockdep_assert_held(&wq_pool_attach_mutex); 2873 2874 /* sanity check frenzy */ 2875 if (WARN_ON(worker->current_work) || 2876 WARN_ON(!list_empty(&worker->scheduled)) || 2877 WARN_ON(!(worker->flags & WORKER_IDLE))) 2878 return; 2879 2880 pool->nr_workers--; 2881 pool->nr_idle--; 2882 2883 worker->flags |= WORKER_DIE; 2884 2885 list_move(&worker->entry, list); 2886 2887 /* get an extra task struct reference for later kthread_stop_put() */ 2888 get_task_struct(worker->task); 2889 } 2890 2891 /** 2892 * idle_worker_timeout - check if some idle workers can now be deleted. 2893 * @t: The pool's idle_timer that just expired 2894 * 2895 * The timer is armed in worker_enter_idle(). Note that it isn't disarmed in 2896 * worker_leave_idle(), as a worker flicking between idle and active while its 2897 * pool is at the too_many_workers() tipping point would cause too much timer 2898 * housekeeping overhead. Since IDLE_WORKER_TIMEOUT is long enough, we just let 2899 * it expire and re-evaluate things from there. 2900 */ 2901 static void idle_worker_timeout(struct timer_list *t) 2902 { 2903 struct worker_pool *pool = from_timer(pool, t, idle_timer); 2904 bool do_cull = false; 2905 2906 if (work_pending(&pool->idle_cull_work)) 2907 return; 2908 2909 raw_spin_lock_irq(&pool->lock); 2910 2911 if (too_many_workers(pool)) { 2912 struct worker *worker; 2913 unsigned long expires; 2914 2915 /* idle_list is kept in LIFO order, check the last one */ 2916 worker = list_last_entry(&pool->idle_list, struct worker, entry); 2917 expires = worker->last_active + IDLE_WORKER_TIMEOUT; 2918 do_cull = !time_before(jiffies, expires); 2919 2920 if (!do_cull) 2921 mod_timer(&pool->idle_timer, expires); 2922 } 2923 raw_spin_unlock_irq(&pool->lock); 2924 2925 if (do_cull) 2926 queue_work(system_unbound_wq, &pool->idle_cull_work); 2927 } 2928 2929 /** 2930 * idle_cull_fn - cull workers that have been idle for too long. 2931 * @work: the pool's work for handling these idle workers 2932 * 2933 * This goes through a pool's idle workers and gets rid of those that have been 2934 * idle for at least IDLE_WORKER_TIMEOUT seconds. 2935 * 2936 * We don't want to disturb isolated CPUs because of a pcpu kworker being 2937 * culled, so this also resets worker affinity. This requires a sleepable 2938 * context, hence the split between timer callback and work item. 2939 */ 2940 static void idle_cull_fn(struct work_struct *work) 2941 { 2942 struct worker_pool *pool = container_of(work, struct worker_pool, idle_cull_work); 2943 LIST_HEAD(cull_list); 2944 2945 /* 2946 * Grabbing wq_pool_attach_mutex here ensures an already-running worker 2947 * cannot proceed beyong set_pf_worker() in its self-destruct path. 2948 * This is required as a previously-preempted worker could run after 2949 * set_worker_dying() has happened but before detach_dying_workers() did. 2950 */ 2951 mutex_lock(&wq_pool_attach_mutex); 2952 raw_spin_lock_irq(&pool->lock); 2953 2954 while (too_many_workers(pool)) { 2955 struct worker *worker; 2956 unsigned long expires; 2957 2958 worker = list_last_entry(&pool->idle_list, struct worker, entry); 2959 expires = worker->last_active + IDLE_WORKER_TIMEOUT; 2960 2961 if (time_before(jiffies, expires)) { 2962 mod_timer(&pool->idle_timer, expires); 2963 break; 2964 } 2965 2966 set_worker_dying(worker, &cull_list); 2967 } 2968 2969 raw_spin_unlock_irq(&pool->lock); 2970 detach_dying_workers(&cull_list); 2971 mutex_unlock(&wq_pool_attach_mutex); 2972 2973 reap_dying_workers(&cull_list); 2974 } 2975 2976 static void send_mayday(struct work_struct *work) 2977 { 2978 struct pool_workqueue *pwq = get_work_pwq(work); 2979 struct workqueue_struct *wq = pwq->wq; 2980 2981 lockdep_assert_held(&wq_mayday_lock); 2982 2983 if (!wq->rescuer) 2984 return; 2985 2986 /* mayday mayday mayday */ 2987 if (list_empty(&pwq->mayday_node)) { 2988 /* 2989 * If @pwq is for an unbound wq, its base ref may be put at 2990 * any time due to an attribute change. Pin @pwq until the 2991 * rescuer is done with it. 2992 */ 2993 get_pwq(pwq); 2994 list_add_tail(&pwq->mayday_node, &wq->maydays); 2995 wake_up_process(wq->rescuer->task); 2996 pwq->stats[PWQ_STAT_MAYDAY]++; 2997 } 2998 } 2999 3000 static void pool_mayday_timeout(struct timer_list *t) 3001 { 3002 struct worker_pool *pool = from_timer(pool, t, mayday_timer); 3003 struct work_struct *work; 3004 3005 raw_spin_lock_irq(&pool->lock); 3006 raw_spin_lock(&wq_mayday_lock); /* for wq->maydays */ 3007 3008 if (need_to_create_worker(pool)) { 3009 /* 3010 * We've been trying to create a new worker but 3011 * haven't been successful. We might be hitting an 3012 * allocation deadlock. Send distress signals to 3013 * rescuers. 3014 */ 3015 list_for_each_entry(work, &pool->worklist, entry) 3016 send_mayday(work); 3017 } 3018 3019 raw_spin_unlock(&wq_mayday_lock); 3020 raw_spin_unlock_irq(&pool->lock); 3021 3022 mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL); 3023 } 3024 3025 /** 3026 * maybe_create_worker - create a new worker if necessary 3027 * @pool: pool to create a new worker for 3028 * 3029 * Create a new worker for @pool if necessary. @pool is guaranteed to 3030 * have at least one idle worker on return from this function. If 3031 * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is 3032 * sent to all rescuers with works scheduled on @pool to resolve 3033 * possible allocation deadlock. 3034 * 3035 * On return, need_to_create_worker() is guaranteed to be %false and 3036 * may_start_working() %true. 3037 * 3038 * LOCKING: 3039 * raw_spin_lock_irq(pool->lock) which may be released and regrabbed 3040 * multiple times. Does GFP_KERNEL allocations. Called only from 3041 * manager. 3042 */ 3043 static void maybe_create_worker(struct worker_pool *pool) 3044 __releases(&pool->lock) 3045 __acquires(&pool->lock) 3046 { 3047 restart: 3048 raw_spin_unlock_irq(&pool->lock); 3049 3050 /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ 3051 mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); 3052 3053 while (true) { 3054 if (create_worker(pool) || !need_to_create_worker(pool)) 3055 break; 3056 3057 schedule_timeout_interruptible(CREATE_COOLDOWN); 3058 3059 if (!need_to_create_worker(pool)) 3060 break; 3061 } 3062 3063 del_timer_sync(&pool->mayday_timer); 3064 raw_spin_lock_irq(&pool->lock); 3065 /* 3066 * This is necessary even after a new worker was just successfully 3067 * created as @pool->lock was dropped and the new worker might have 3068 * already become busy. 3069 */ 3070 if (need_to_create_worker(pool)) 3071 goto restart; 3072 } 3073 3074 /** 3075 * manage_workers - manage worker pool 3076 * @worker: self 3077 * 3078 * Assume the manager role and manage the worker pool @worker belongs 3079 * to. At any given time, there can be only zero or one manager per 3080 * pool. The exclusion is handled automatically by this function. 3081 * 3082 * The caller can safely start processing works on false return. On 3083 * true return, it's guaranteed that need_to_create_worker() is false 3084 * and may_start_working() is true. 3085 * 3086 * CONTEXT: 3087 * raw_spin_lock_irq(pool->lock) which may be released and regrabbed 3088 * multiple times. Does GFP_KERNEL allocations. 3089 * 3090 * Return: 3091 * %false if the pool doesn't need management and the caller can safely 3092 * start processing works, %true if management function was performed and 3093 * the conditions that the caller verified before calling the function may 3094 * no longer be true. 3095 */ 3096 static bool manage_workers(struct worker *worker) 3097 { 3098 struct worker_pool *pool = worker->pool; 3099 3100 if (pool->flags & POOL_MANAGER_ACTIVE) 3101 return false; 3102 3103 pool->flags |= POOL_MANAGER_ACTIVE; 3104 pool->manager = worker; 3105 3106 maybe_create_worker(pool); 3107 3108 pool->manager = NULL; 3109 pool->flags &= ~POOL_MANAGER_ACTIVE; 3110 rcuwait_wake_up(&manager_wait); 3111 return true; 3112 } 3113 3114 /** 3115 * process_one_work - process single work 3116 * @worker: self 3117 * @work: work to process 3118 * 3119 * Process @work. This function contains all the logics necessary to 3120 * process a single work including synchronization against and 3121 * interaction with other workers on the same cpu, queueing and 3122 * flushing. As long as context requirement is met, any worker can 3123 * call this function to process a work. 3124 * 3125 * CONTEXT: 3126 * raw_spin_lock_irq(pool->lock) which is released and regrabbed. 3127 */ 3128 static void process_one_work(struct worker *worker, struct work_struct *work) 3129 __releases(&pool->lock) 3130 __acquires(&pool->lock) 3131 { 3132 struct pool_workqueue *pwq = get_work_pwq(work); 3133 struct worker_pool *pool = worker->pool; 3134 unsigned long work_data; 3135 int lockdep_start_depth, rcu_start_depth; 3136 bool bh_draining = pool->flags & POOL_BH_DRAINING; 3137 #ifdef CONFIG_LOCKDEP 3138 /* 3139 * It is permissible to free the struct work_struct from 3140 * inside the function that is called from it, this we need to 3141 * take into account for lockdep too. To avoid bogus "held 3142 * lock freed" warnings as well as problems when looking into 3143 * work->lockdep_map, make a copy and use that here. 3144 */ 3145 struct lockdep_map lockdep_map; 3146 3147 lockdep_copy_map(&lockdep_map, &work->lockdep_map); 3148 #endif 3149 /* ensure we're on the correct CPU */ 3150 WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && 3151 raw_smp_processor_id() != pool->cpu); 3152 3153 /* claim and dequeue */ 3154 debug_work_deactivate(work); 3155 hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work); 3156 worker->current_work = work; 3157 worker->current_func = work->func; 3158 worker->current_pwq = pwq; 3159 if (worker->task) 3160 worker->current_at = worker->task->se.sum_exec_runtime; 3161 work_data = *work_data_bits(work); 3162 worker->current_color = get_work_color(work_data); 3163 3164 /* 3165 * Record wq name for cmdline and debug reporting, may get 3166 * overridden through set_worker_desc(). 3167 */ 3168 strscpy(worker->desc, pwq->wq->name, WORKER_DESC_LEN); 3169 3170 list_del_init(&work->entry); 3171 3172 /* 3173 * CPU intensive works don't participate in concurrency management. 3174 * They're the scheduler's responsibility. This takes @worker out 3175 * of concurrency management and the next code block will chain 3176 * execution of the pending work items. 3177 */ 3178 if (unlikely(pwq->wq->flags & WQ_CPU_INTENSIVE)) 3179 worker_set_flags(worker, WORKER_CPU_INTENSIVE); 3180 3181 /* 3182 * Kick @pool if necessary. It's always noop for per-cpu worker pools 3183 * since nr_running would always be >= 1 at this point. This is used to 3184 * chain execution of the pending work items for WORKER_NOT_RUNNING 3185 * workers such as the UNBOUND and CPU_INTENSIVE ones. 3186 */ 3187 kick_pool(pool); 3188 3189 /* 3190 * Record the last pool and clear PENDING which should be the last 3191 * update to @work. Also, do this inside @pool->lock so that 3192 * PENDING and queued state changes happen together while IRQ is 3193 * disabled. 3194 */ 3195 set_work_pool_and_clear_pending(work, pool->id, pool_offq_flags(pool)); 3196 3197 pwq->stats[PWQ_STAT_STARTED]++; 3198 raw_spin_unlock_irq(&pool->lock); 3199 3200 rcu_start_depth = rcu_preempt_depth(); 3201 lockdep_start_depth = lockdep_depth(current); 3202 /* see drain_dead_softirq_workfn() */ 3203 if (!bh_draining) 3204 lock_map_acquire(pwq->wq->lockdep_map); 3205 lock_map_acquire(&lockdep_map); 3206 /* 3207 * Strictly speaking we should mark the invariant state without holding 3208 * any locks, that is, before these two lock_map_acquire()'s. 3209 * 3210 * However, that would result in: 3211 * 3212 * A(W1) 3213 * WFC(C) 3214 * A(W1) 3215 * C(C) 3216 * 3217 * Which would create W1->C->W1 dependencies, even though there is no 3218 * actual deadlock possible. There are two solutions, using a 3219 * read-recursive acquire on the work(queue) 'locks', but this will then 3220 * hit the lockdep limitation on recursive locks, or simply discard 3221 * these locks. 3222 * 3223 * AFAICT there is no possible deadlock scenario between the 3224 * flush_work() and complete() primitives (except for single-threaded 3225 * workqueues), so hiding them isn't a problem. 3226 */ 3227 lockdep_invariant_state(true); 3228 trace_workqueue_execute_start(work); 3229 worker->current_func(work); 3230 /* 3231 * While we must be careful to not use "work" after this, the trace 3232 * point will only record its address. 3233 */ 3234 trace_workqueue_execute_end(work, worker->current_func); 3235 pwq->stats[PWQ_STAT_COMPLETED]++; 3236 lock_map_release(&lockdep_map); 3237 if (!bh_draining) 3238 lock_map_release(pwq->wq->lockdep_map); 3239 3240 if (unlikely((worker->task && in_atomic()) || 3241 lockdep_depth(current) != lockdep_start_depth || 3242 rcu_preempt_depth() != rcu_start_depth)) { 3243 pr_err("BUG: workqueue leaked atomic, lock or RCU: %s[%d]\n" 3244 " preempt=0x%08x lock=%d->%d RCU=%d->%d workfn=%ps\n", 3245 current->comm, task_pid_nr(current), preempt_count(), 3246 lockdep_start_depth, lockdep_depth(current), 3247 rcu_start_depth, rcu_preempt_depth(), 3248 worker->current_func); 3249 debug_show_held_locks(current); 3250 dump_stack(); 3251 } 3252 3253 /* 3254 * The following prevents a kworker from hogging CPU on !PREEMPTION 3255 * kernels, where a requeueing work item waiting for something to 3256 * happen could deadlock with stop_machine as such work item could 3257 * indefinitely requeue itself while all other CPUs are trapped in 3258 * stop_machine. At the same time, report a quiescent RCU state so 3259 * the same condition doesn't freeze RCU. 3260 */ 3261 if (worker->task) 3262 cond_resched(); 3263 3264 raw_spin_lock_irq(&pool->lock); 3265 3266 /* 3267 * In addition to %WQ_CPU_INTENSIVE, @worker may also have been marked 3268 * CPU intensive by wq_worker_tick() if @work hogged CPU longer than 3269 * wq_cpu_intensive_thresh_us. Clear it. 3270 */ 3271 worker_clr_flags(worker, WORKER_CPU_INTENSIVE); 3272 3273 /* tag the worker for identification in schedule() */ 3274 worker->last_func = worker->current_func; 3275 3276 /* we're done with it, release */ 3277 hash_del(&worker->hentry); 3278 worker->current_work = NULL; 3279 worker->current_func = NULL; 3280 worker->current_pwq = NULL; 3281 worker->current_color = INT_MAX; 3282 3283 /* must be the last step, see the function comment */ 3284 pwq_dec_nr_in_flight(pwq, work_data); 3285 } 3286 3287 /** 3288 * process_scheduled_works - process scheduled works 3289 * @worker: self 3290 * 3291 * Process all scheduled works. Please note that the scheduled list 3292 * may change while processing a work, so this function repeatedly 3293 * fetches a work from the top and executes it. 3294 * 3295 * CONTEXT: 3296 * raw_spin_lock_irq(pool->lock) which may be released and regrabbed 3297 * multiple times. 3298 */ 3299 static void process_scheduled_works(struct worker *worker) 3300 { 3301 struct work_struct *work; 3302 bool first = true; 3303 3304 while ((work = list_first_entry_or_null(&worker->scheduled, 3305 struct work_struct, entry))) { 3306 if (first) { 3307 worker->pool->watchdog_ts = jiffies; 3308 first = false; 3309 } 3310 process_one_work(worker, work); 3311 } 3312 } 3313 3314 static void set_pf_worker(bool val) 3315 { 3316 mutex_lock(&wq_pool_attach_mutex); 3317 if (val) 3318 current->flags |= PF_WQ_WORKER; 3319 else 3320 current->flags &= ~PF_WQ_WORKER; 3321 mutex_unlock(&wq_pool_attach_mutex); 3322 } 3323 3324 /** 3325 * worker_thread - the worker thread function 3326 * @__worker: self 3327 * 3328 * The worker thread function. All workers belong to a worker_pool - 3329 * either a per-cpu one or dynamic unbound one. These workers process all 3330 * work items regardless of their specific target workqueue. The only 3331 * exception is work items which belong to workqueues with a rescuer which 3332 * will be explained in rescuer_thread(). 3333 * 3334 * Return: 0 3335 */ 3336 static int worker_thread(void *__worker) 3337 { 3338 struct worker *worker = __worker; 3339 struct worker_pool *pool = worker->pool; 3340 3341 /* tell the scheduler that this is a workqueue worker */ 3342 set_pf_worker(true); 3343 woke_up: 3344 raw_spin_lock_irq(&pool->lock); 3345 3346 /* am I supposed to die? */ 3347 if (unlikely(worker->flags & WORKER_DIE)) { 3348 raw_spin_unlock_irq(&pool->lock); 3349 set_pf_worker(false); 3350 /* 3351 * The worker is dead and PF_WQ_WORKER is cleared, worker->pool 3352 * shouldn't be accessed, reset it to NULL in case otherwise. 3353 */ 3354 worker->pool = NULL; 3355 ida_free(&pool->worker_ida, worker->id); 3356 return 0; 3357 } 3358 3359 worker_leave_idle(worker); 3360 recheck: 3361 /* no more worker necessary? */ 3362 if (!need_more_worker(pool)) 3363 goto sleep; 3364 3365 /* do we need to manage? */ 3366 if (unlikely(!may_start_working(pool)) && manage_workers(worker)) 3367 goto recheck; 3368 3369 /* 3370 * ->scheduled list can only be filled while a worker is 3371 * preparing to process a work or actually processing it. 3372 * Make sure nobody diddled with it while I was sleeping. 3373 */ 3374 WARN_ON_ONCE(!list_empty(&worker->scheduled)); 3375 3376 /* 3377 * Finish PREP stage. We're guaranteed to have at least one idle 3378 * worker or that someone else has already assumed the manager 3379 * role. This is where @worker starts participating in concurrency 3380 * management if applicable and concurrency management is restored 3381 * after being rebound. See rebind_workers() for details. 3382 */ 3383 worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND); 3384 3385 do { 3386 struct work_struct *work = 3387 list_first_entry(&pool->worklist, 3388 struct work_struct, entry); 3389 3390 if (assign_work(work, worker, NULL)) 3391 process_scheduled_works(worker); 3392 } while (keep_working(pool)); 3393 3394 worker_set_flags(worker, WORKER_PREP); 3395 sleep: 3396 /* 3397 * pool->lock is held and there's no work to process and no need to 3398 * manage, sleep. Workers are woken up only while holding 3399 * pool->lock or from local cpu, so setting the current state 3400 * before releasing pool->lock is enough to prevent losing any 3401 * event. 3402 */ 3403 worker_enter_idle(worker); 3404 __set_current_state(TASK_IDLE); 3405 raw_spin_unlock_irq(&pool->lock); 3406 schedule(); 3407 goto woke_up; 3408 } 3409 3410 /** 3411 * rescuer_thread - the rescuer thread function 3412 * @__rescuer: self 3413 * 3414 * Workqueue rescuer thread function. There's one rescuer for each 3415 * workqueue which has WQ_MEM_RECLAIM set. 3416 * 3417 * Regular work processing on a pool may block trying to create a new 3418 * worker which uses GFP_KERNEL allocation which has slight chance of 3419 * developing into deadlock if some works currently on the same queue 3420 * need to be processed to satisfy the GFP_KERNEL allocation. This is 3421 * the problem rescuer solves. 3422 * 3423 * When such condition is possible, the pool summons rescuers of all 3424 * workqueues which have works queued on the pool and let them process 3425 * those works so that forward progress can be guaranteed. 3426 * 3427 * This should happen rarely. 3428 * 3429 * Return: 0 3430 */ 3431 static int rescuer_thread(void *__rescuer) 3432 { 3433 struct worker *rescuer = __rescuer; 3434 struct workqueue_struct *wq = rescuer->rescue_wq; 3435 bool should_stop; 3436 3437 set_user_nice(current, RESCUER_NICE_LEVEL); 3438 3439 /* 3440 * Mark rescuer as worker too. As WORKER_PREP is never cleared, it 3441 * doesn't participate in concurrency management. 3442 */ 3443 set_pf_worker(true); 3444 repeat: 3445 set_current_state(TASK_IDLE); 3446 3447 /* 3448 * By the time the rescuer is requested to stop, the workqueue 3449 * shouldn't have any work pending, but @wq->maydays may still have 3450 * pwq(s) queued. This can happen by non-rescuer workers consuming 3451 * all the work items before the rescuer got to them. Go through 3452 * @wq->maydays processing before acting on should_stop so that the 3453 * list is always empty on exit. 3454 */ 3455 should_stop = kthread_should_stop(); 3456 3457 /* see whether any pwq is asking for help */ 3458 raw_spin_lock_irq(&wq_mayday_lock); 3459 3460 while (!list_empty(&wq->maydays)) { 3461 struct pool_workqueue *pwq = list_first_entry(&wq->maydays, 3462 struct pool_workqueue, mayday_node); 3463 struct worker_pool *pool = pwq->pool; 3464 struct work_struct *work, *n; 3465 3466 __set_current_state(TASK_RUNNING); 3467 list_del_init(&pwq->mayday_node); 3468 3469 raw_spin_unlock_irq(&wq_mayday_lock); 3470 3471 worker_attach_to_pool(rescuer, pool); 3472 3473 raw_spin_lock_irq(&pool->lock); 3474 3475 /* 3476 * Slurp in all works issued via this workqueue and 3477 * process'em. 3478 */ 3479 WARN_ON_ONCE(!list_empty(&rescuer->scheduled)); 3480 list_for_each_entry_safe(work, n, &pool->worklist, entry) { 3481 if (get_work_pwq(work) == pwq && 3482 assign_work(work, rescuer, &n)) 3483 pwq->stats[PWQ_STAT_RESCUED]++; 3484 } 3485 3486 if (!list_empty(&rescuer->scheduled)) { 3487 process_scheduled_works(rescuer); 3488 3489 /* 3490 * The above execution of rescued work items could 3491 * have created more to rescue through 3492 * pwq_activate_first_inactive() or chained 3493 * queueing. Let's put @pwq back on mayday list so 3494 * that such back-to-back work items, which may be 3495 * being used to relieve memory pressure, don't 3496 * incur MAYDAY_INTERVAL delay inbetween. 3497 */ 3498 if (pwq->nr_active && need_to_create_worker(pool)) { 3499 raw_spin_lock(&wq_mayday_lock); 3500 /* 3501 * Queue iff we aren't racing destruction 3502 * and somebody else hasn't queued it already. 3503 */ 3504 if (wq->rescuer && list_empty(&pwq->mayday_node)) { 3505 get_pwq(pwq); 3506 list_add_tail(&pwq->mayday_node, &wq->maydays); 3507 } 3508 raw_spin_unlock(&wq_mayday_lock); 3509 } 3510 } 3511 3512 /* 3513 * Put the reference grabbed by send_mayday(). @pool won't 3514 * go away while we're still attached to it. 3515 */ 3516 put_pwq(pwq); 3517 3518 /* 3519 * Leave this pool. Notify regular workers; otherwise, we end up 3520 * with 0 concurrency and stalling the execution. 3521 */ 3522 kick_pool(pool); 3523 3524 raw_spin_unlock_irq(&pool->lock); 3525 3526 worker_detach_from_pool(rescuer); 3527 3528 raw_spin_lock_irq(&wq_mayday_lock); 3529 } 3530 3531 raw_spin_unlock_irq(&wq_mayday_lock); 3532 3533 if (should_stop) { 3534 __set_current_state(TASK_RUNNING); 3535 set_pf_worker(false); 3536 return 0; 3537 } 3538 3539 /* rescuers should never participate in concurrency management */ 3540 WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING)); 3541 schedule(); 3542 goto repeat; 3543 } 3544 3545 static void bh_worker(struct worker *worker) 3546 { 3547 struct worker_pool *pool = worker->pool; 3548 int nr_restarts = BH_WORKER_RESTARTS; 3549 unsigned long end = jiffies + BH_WORKER_JIFFIES; 3550 3551 raw_spin_lock_irq(&pool->lock); 3552 worker_leave_idle(worker); 3553 3554 /* 3555 * This function follows the structure of worker_thread(). See there for 3556 * explanations on each step. 3557 */ 3558 if (!need_more_worker(pool)) 3559 goto done; 3560 3561 WARN_ON_ONCE(!list_empty(&worker->scheduled)); 3562 worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND); 3563 3564 do { 3565 struct work_struct *work = 3566 list_first_entry(&pool->worklist, 3567 struct work_struct, entry); 3568 3569 if (assign_work(work, worker, NULL)) 3570 process_scheduled_works(worker); 3571 } while (keep_working(pool) && 3572 --nr_restarts && time_before(jiffies, end)); 3573 3574 worker_set_flags(worker, WORKER_PREP); 3575 done: 3576 worker_enter_idle(worker); 3577 kick_pool(pool); 3578 raw_spin_unlock_irq(&pool->lock); 3579 } 3580 3581 /* 3582 * TODO: Convert all tasklet users to workqueue and use softirq directly. 3583 * 3584 * This is currently called from tasklet[_hi]action() and thus is also called 3585 * whenever there are tasklets to run. Let's do an early exit if there's nothing 3586 * queued. Once conversion from tasklet is complete, the need_more_worker() test 3587 * can be dropped. 3588 * 3589 * After full conversion, we'll add worker->softirq_action, directly use the 3590 * softirq action and obtain the worker pointer from the softirq_action pointer. 3591 */ 3592 void workqueue_softirq_action(bool highpri) 3593 { 3594 struct worker_pool *pool = 3595 &per_cpu(bh_worker_pools, smp_processor_id())[highpri]; 3596 if (need_more_worker(pool)) 3597 bh_worker(list_first_entry(&pool->workers, struct worker, node)); 3598 } 3599 3600 struct wq_drain_dead_softirq_work { 3601 struct work_struct work; 3602 struct worker_pool *pool; 3603 struct completion done; 3604 }; 3605 3606 static void drain_dead_softirq_workfn(struct work_struct *work) 3607 { 3608 struct wq_drain_dead_softirq_work *dead_work = 3609 container_of(work, struct wq_drain_dead_softirq_work, work); 3610 struct worker_pool *pool = dead_work->pool; 3611 bool repeat; 3612 3613 /* 3614 * @pool's CPU is dead and we want to execute its still pending work 3615 * items from this BH work item which is running on a different CPU. As 3616 * its CPU is dead, @pool can't be kicked and, as work execution path 3617 * will be nested, a lockdep annotation needs to be suppressed. Mark 3618 * @pool with %POOL_BH_DRAINING for the special treatments. 3619 */ 3620 raw_spin_lock_irq(&pool->lock); 3621 pool->flags |= POOL_BH_DRAINING; 3622 raw_spin_unlock_irq(&pool->lock); 3623 3624 bh_worker(list_first_entry(&pool->workers, struct worker, node)); 3625 3626 raw_spin_lock_irq(&pool->lock); 3627 pool->flags &= ~POOL_BH_DRAINING; 3628 repeat = need_more_worker(pool); 3629 raw_spin_unlock_irq(&pool->lock); 3630 3631 /* 3632 * bh_worker() might hit consecutive execution limit and bail. If there 3633 * still are pending work items, reschedule self and return so that we 3634 * don't hog this CPU's BH. 3635 */ 3636 if (repeat) { 3637 if (pool->attrs->nice == HIGHPRI_NICE_LEVEL) 3638 queue_work(system_bh_highpri_wq, work); 3639 else 3640 queue_work(system_bh_wq, work); 3641 } else { 3642 complete(&dead_work->done); 3643 } 3644 } 3645 3646 /* 3647 * @cpu is dead. Drain the remaining BH work items on the current CPU. It's 3648 * possible to allocate dead_work per CPU and avoid flushing. However, then we 3649 * have to worry about draining overlapping with CPU coming back online or 3650 * nesting (one CPU's dead_work queued on another CPU which is also dead and so 3651 * on). Let's keep it simple and drain them synchronously. These are BH work 3652 * items which shouldn't be requeued on the same pool. Shouldn't take long. 3653 */ 3654 void workqueue_softirq_dead(unsigned int cpu) 3655 { 3656 int i; 3657 3658 for (i = 0; i < NR_STD_WORKER_POOLS; i++) { 3659 struct worker_pool *pool = &per_cpu(bh_worker_pools, cpu)[i]; 3660 struct wq_drain_dead_softirq_work dead_work; 3661 3662 if (!need_more_worker(pool)) 3663 continue; 3664 3665 INIT_WORK_ONSTACK(&dead_work.work, drain_dead_softirq_workfn); 3666 dead_work.pool = pool; 3667 init_completion(&dead_work.done); 3668 3669 if (pool->attrs->nice == HIGHPRI_NICE_LEVEL) 3670 queue_work(system_bh_highpri_wq, &dead_work.work); 3671 else 3672 queue_work(system_bh_wq, &dead_work.work); 3673 3674 wait_for_completion(&dead_work.done); 3675 destroy_work_on_stack(&dead_work.work); 3676 } 3677 } 3678 3679 /** 3680 * check_flush_dependency - check for flush dependency sanity 3681 * @target_wq: workqueue being flushed 3682 * @target_work: work item being flushed (NULL for workqueue flushes) 3683 * 3684 * %current is trying to flush the whole @target_wq or @target_work on it. 3685 * If @target_wq doesn't have %WQ_MEM_RECLAIM, verify that %current is not 3686 * reclaiming memory or running on a workqueue which doesn't have 3687 * %WQ_MEM_RECLAIM as that can break forward-progress guarantee leading to 3688 * a deadlock. 3689 */ 3690 static void check_flush_dependency(struct workqueue_struct *target_wq, 3691 struct work_struct *target_work) 3692 { 3693 work_func_t target_func = target_work ? target_work->func : NULL; 3694 struct worker *worker; 3695 3696 if (target_wq->flags & WQ_MEM_RECLAIM) 3697 return; 3698 3699 worker = current_wq_worker(); 3700 3701 WARN_ONCE(current->flags & PF_MEMALLOC, 3702 "workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%ps", 3703 current->pid, current->comm, target_wq->name, target_func); 3704 WARN_ONCE(worker && ((worker->current_pwq->wq->flags & 3705 (WQ_MEM_RECLAIM | __WQ_LEGACY)) == WQ_MEM_RECLAIM), 3706 "workqueue: WQ_MEM_RECLAIM %s:%ps is flushing !WQ_MEM_RECLAIM %s:%ps", 3707 worker->current_pwq->wq->name, worker->current_func, 3708 target_wq->name, target_func); 3709 } 3710 3711 struct wq_barrier { 3712 struct work_struct work; 3713 struct completion done; 3714 struct task_struct *task; /* purely informational */ 3715 }; 3716 3717 static void wq_barrier_func(struct work_struct *work) 3718 { 3719 struct wq_barrier *barr = container_of(work, struct wq_barrier, work); 3720 complete(&barr->done); 3721 } 3722 3723 /** 3724 * insert_wq_barrier - insert a barrier work 3725 * @pwq: pwq to insert barrier into 3726 * @barr: wq_barrier to insert 3727 * @target: target work to attach @barr to 3728 * @worker: worker currently executing @target, NULL if @target is not executing 3729 * 3730 * @barr is linked to @target such that @barr is completed only after 3731 * @target finishes execution. Please note that the ordering 3732 * guarantee is observed only with respect to @target and on the local 3733 * cpu. 3734 * 3735 * Currently, a queued barrier can't be canceled. This is because 3736 * try_to_grab_pending() can't determine whether the work to be 3737 * grabbed is at the head of the queue and thus can't clear LINKED 3738 * flag of the previous work while there must be a valid next work 3739 * after a work with LINKED flag set. 3740 * 3741 * Note that when @worker is non-NULL, @target may be modified 3742 * underneath us, so we can't reliably determine pwq from @target. 3743 * 3744 * CONTEXT: 3745 * raw_spin_lock_irq(pool->lock). 3746 */ 3747 static void insert_wq_barrier(struct pool_workqueue *pwq, 3748 struct wq_barrier *barr, 3749 struct work_struct *target, struct worker *worker) 3750 { 3751 static __maybe_unused struct lock_class_key bh_key, thr_key; 3752 unsigned int work_flags = 0; 3753 unsigned int work_color; 3754 struct list_head *head; 3755 3756 /* 3757 * debugobject calls are safe here even with pool->lock locked 3758 * as we know for sure that this will not trigger any of the 3759 * checks and call back into the fixup functions where we 3760 * might deadlock. 3761 * 3762 * BH and threaded workqueues need separate lockdep keys to avoid 3763 * spuriously triggering "inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} 3764 * usage". 3765 */ 3766 INIT_WORK_ONSTACK_KEY(&barr->work, wq_barrier_func, 3767 (pwq->wq->flags & WQ_BH) ? &bh_key : &thr_key); 3768 __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); 3769 3770 init_completion_map(&barr->done, &target->lockdep_map); 3771 3772 barr->task = current; 3773 3774 /* The barrier work item does not participate in nr_active. */ 3775 work_flags |= WORK_STRUCT_INACTIVE; 3776 3777 /* 3778 * If @target is currently being executed, schedule the 3779 * barrier to the worker; otherwise, put it after @target. 3780 */ 3781 if (worker) { 3782 head = worker->scheduled.next; 3783 work_color = worker->current_color; 3784 } else { 3785 unsigned long *bits = work_data_bits(target); 3786 3787 head = target->entry.next; 3788 /* there can already be other linked works, inherit and set */ 3789 work_flags |= *bits & WORK_STRUCT_LINKED; 3790 work_color = get_work_color(*bits); 3791 __set_bit(WORK_STRUCT_LINKED_BIT, bits); 3792 } 3793 3794 pwq->nr_in_flight[work_color]++; 3795 work_flags |= work_color_to_flags(work_color); 3796 3797 insert_work(pwq, &barr->work, head, work_flags); 3798 } 3799 3800 /** 3801 * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing 3802 * @wq: workqueue being flushed 3803 * @flush_color: new flush color, < 0 for no-op 3804 * @work_color: new work color, < 0 for no-op 3805 * 3806 * Prepare pwqs for workqueue flushing. 3807 * 3808 * If @flush_color is non-negative, flush_color on all pwqs should be 3809 * -1. If no pwq has in-flight commands at the specified color, all 3810 * pwq->flush_color's stay at -1 and %false is returned. If any pwq 3811 * has in flight commands, its pwq->flush_color is set to 3812 * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq 3813 * wakeup logic is armed and %true is returned. 3814 * 3815 * The caller should have initialized @wq->first_flusher prior to 3816 * calling this function with non-negative @flush_color. If 3817 * @flush_color is negative, no flush color update is done and %false 3818 * is returned. 3819 * 3820 * If @work_color is non-negative, all pwqs should have the same 3821 * work_color which is previous to @work_color and all will be 3822 * advanced to @work_color. 3823 * 3824 * CONTEXT: 3825 * mutex_lock(wq->mutex). 3826 * 3827 * Return: 3828 * %true if @flush_color >= 0 and there's something to flush. %false 3829 * otherwise. 3830 */ 3831 static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq, 3832 int flush_color, int work_color) 3833 { 3834 bool wait = false; 3835 struct pool_workqueue *pwq; 3836 struct worker_pool *current_pool = NULL; 3837 3838 if (flush_color >= 0) { 3839 WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush)); 3840 atomic_set(&wq->nr_pwqs_to_flush, 1); 3841 } 3842 3843 /* 3844 * For unbound workqueue, pwqs will map to only a few pools. 3845 * Most of the time, pwqs within the same pool will be linked 3846 * sequentially to wq->pwqs by cpu index. So in the majority 3847 * of pwq iters, the pool is the same, only doing lock/unlock 3848 * if the pool has changed. This can largely reduce expensive 3849 * lock operations. 3850 */ 3851 for_each_pwq(pwq, wq) { 3852 if (current_pool != pwq->pool) { 3853 if (likely(current_pool)) 3854 raw_spin_unlock_irq(¤t_pool->lock); 3855 current_pool = pwq->pool; 3856 raw_spin_lock_irq(¤t_pool->lock); 3857 } 3858 3859 if (flush_color >= 0) { 3860 WARN_ON_ONCE(pwq->flush_color != -1); 3861 3862 if (pwq->nr_in_flight[flush_color]) { 3863 pwq->flush_color = flush_color; 3864 atomic_inc(&wq->nr_pwqs_to_flush); 3865 wait = true; 3866 } 3867 } 3868 3869 if (work_color >= 0) { 3870 WARN_ON_ONCE(work_color != work_next_color(pwq->work_color)); 3871 pwq->work_color = work_color; 3872 } 3873 3874 } 3875 3876 if (current_pool) 3877 raw_spin_unlock_irq(¤t_pool->lock); 3878 3879 if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush)) 3880 complete(&wq->first_flusher->done); 3881 3882 return wait; 3883 } 3884 3885 static void touch_wq_lockdep_map(struct workqueue_struct *wq) 3886 { 3887 #ifdef CONFIG_LOCKDEP 3888 if (unlikely(!wq->lockdep_map)) 3889 return; 3890 3891 if (wq->flags & WQ_BH) 3892 local_bh_disable(); 3893 3894 lock_map_acquire(wq->lockdep_map); 3895 lock_map_release(wq->lockdep_map); 3896 3897 if (wq->flags & WQ_BH) 3898 local_bh_enable(); 3899 #endif 3900 } 3901 3902 static void touch_work_lockdep_map(struct work_struct *work, 3903 struct workqueue_struct *wq) 3904 { 3905 #ifdef CONFIG_LOCKDEP 3906 if (wq->flags & WQ_BH) 3907 local_bh_disable(); 3908 3909 lock_map_acquire(&work->lockdep_map); 3910 lock_map_release(&work->lockdep_map); 3911 3912 if (wq->flags & WQ_BH) 3913 local_bh_enable(); 3914 #endif 3915 } 3916 3917 /** 3918 * __flush_workqueue - ensure that any scheduled work has run to completion. 3919 * @wq: workqueue to flush 3920 * 3921 * This function sleeps until all work items which were queued on entry 3922 * have finished execution, but it is not livelocked by new incoming ones. 3923 */ 3924 void __flush_workqueue(struct workqueue_struct *wq) 3925 { 3926 struct wq_flusher this_flusher = { 3927 .list = LIST_HEAD_INIT(this_flusher.list), 3928 .flush_color = -1, 3929 .done = COMPLETION_INITIALIZER_ONSTACK_MAP(this_flusher.done, (*wq->lockdep_map)), 3930 }; 3931 int next_color; 3932 3933 if (WARN_ON(!wq_online)) 3934 return; 3935 3936 touch_wq_lockdep_map(wq); 3937 3938 mutex_lock(&wq->mutex); 3939 3940 /* 3941 * Start-to-wait phase 3942 */ 3943 next_color = work_next_color(wq->work_color); 3944 3945 if (next_color != wq->flush_color) { 3946 /* 3947 * Color space is not full. The current work_color 3948 * becomes our flush_color and work_color is advanced 3949 * by one. 3950 */ 3951 WARN_ON_ONCE(!list_empty(&wq->flusher_overflow)); 3952 this_flusher.flush_color = wq->work_color; 3953 wq->work_color = next_color; 3954 3955 if (!wq->first_flusher) { 3956 /* no flush in progress, become the first flusher */ 3957 WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); 3958 3959 wq->first_flusher = &this_flusher; 3960 3961 if (!flush_workqueue_prep_pwqs(wq, wq->flush_color, 3962 wq->work_color)) { 3963 /* nothing to flush, done */ 3964 wq->flush_color = next_color; 3965 wq->first_flusher = NULL; 3966 goto out_unlock; 3967 } 3968 } else { 3969 /* wait in queue */ 3970 WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color); 3971 list_add_tail(&this_flusher.list, &wq->flusher_queue); 3972 flush_workqueue_prep_pwqs(wq, -1, wq->work_color); 3973 } 3974 } else { 3975 /* 3976 * Oops, color space is full, wait on overflow queue. 3977 * The next flush completion will assign us 3978 * flush_color and transfer to flusher_queue. 3979 */ 3980 list_add_tail(&this_flusher.list, &wq->flusher_overflow); 3981 } 3982 3983 check_flush_dependency(wq, NULL); 3984 3985 mutex_unlock(&wq->mutex); 3986 3987 wait_for_completion(&this_flusher.done); 3988 3989 /* 3990 * Wake-up-and-cascade phase 3991 * 3992 * First flushers are responsible for cascading flushes and 3993 * handling overflow. Non-first flushers can simply return. 3994 */ 3995 if (READ_ONCE(wq->first_flusher) != &this_flusher) 3996 return; 3997 3998 mutex_lock(&wq->mutex); 3999 4000 /* we might have raced, check again with mutex held */ 4001 if (wq->first_flusher != &this_flusher) 4002 goto out_unlock; 4003 4004 WRITE_ONCE(wq->first_flusher, NULL); 4005 4006 WARN_ON_ONCE(!list_empty(&this_flusher.list)); 4007 WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); 4008 4009 while (true) { 4010 struct wq_flusher *next, *tmp; 4011 4012 /* complete all the flushers sharing the current flush color */ 4013 list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { 4014 if (next->flush_color != wq->flush_color) 4015 break; 4016 list_del_init(&next->list); 4017 complete(&next->done); 4018 } 4019 4020 WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) && 4021 wq->flush_color != work_next_color(wq->work_color)); 4022 4023 /* this flush_color is finished, advance by one */ 4024 wq->flush_color = work_next_color(wq->flush_color); 4025 4026 /* one color has been freed, handle overflow queue */ 4027 if (!list_empty(&wq->flusher_overflow)) { 4028 /* 4029 * Assign the same color to all overflowed 4030 * flushers, advance work_color and append to 4031 * flusher_queue. This is the start-to-wait 4032 * phase for these overflowed flushers. 4033 */ 4034 list_for_each_entry(tmp, &wq->flusher_overflow, list) 4035 tmp->flush_color = wq->work_color; 4036 4037 wq->work_color = work_next_color(wq->work_color); 4038 4039 list_splice_tail_init(&wq->flusher_overflow, 4040 &wq->flusher_queue); 4041 flush_workqueue_prep_pwqs(wq, -1, wq->work_color); 4042 } 4043 4044 if (list_empty(&wq->flusher_queue)) { 4045 WARN_ON_ONCE(wq->flush_color != wq->work_color); 4046 break; 4047 } 4048 4049 /* 4050 * Need to flush more colors. Make the next flusher 4051 * the new first flusher and arm pwqs. 4052 */ 4053 WARN_ON_ONCE(wq->flush_color == wq->work_color); 4054 WARN_ON_ONCE(wq->flush_color != next->flush_color); 4055 4056 list_del_init(&next->list); 4057 wq->first_flusher = next; 4058 4059 if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1)) 4060 break; 4061 4062 /* 4063 * Meh... this color is already done, clear first 4064 * flusher and repeat cascading. 4065 */ 4066 wq->first_flusher = NULL; 4067 } 4068 4069 out_unlock: 4070 mutex_unlock(&wq->mutex); 4071 } 4072 EXPORT_SYMBOL(__flush_workqueue); 4073 4074 /** 4075 * drain_workqueue - drain a workqueue 4076 * @wq: workqueue to drain 4077 * 4078 * Wait until the workqueue becomes empty. While draining is in progress, 4079 * only chain queueing is allowed. IOW, only currently pending or running 4080 * work items on @wq can queue further work items on it. @wq is flushed 4081 * repeatedly until it becomes empty. The number of flushing is determined 4082 * by the depth of chaining and should be relatively short. Whine if it 4083 * takes too long. 4084 */ 4085 void drain_workqueue(struct workqueue_struct *wq) 4086 { 4087 unsigned int flush_cnt = 0; 4088 struct pool_workqueue *pwq; 4089 4090 /* 4091 * __queue_work() needs to test whether there are drainers, is much 4092 * hotter than drain_workqueue() and already looks at @wq->flags. 4093 * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers. 4094 */ 4095 mutex_lock(&wq->mutex); 4096 if (!wq->nr_drainers++) 4097 wq->flags |= __WQ_DRAINING; 4098 mutex_unlock(&wq->mutex); 4099 reflush: 4100 __flush_workqueue(wq); 4101 4102 mutex_lock(&wq->mutex); 4103 4104 for_each_pwq(pwq, wq) { 4105 bool drained; 4106 4107 raw_spin_lock_irq(&pwq->pool->lock); 4108 drained = pwq_is_empty(pwq); 4109 raw_spin_unlock_irq(&pwq->pool->lock); 4110 4111 if (drained) 4112 continue; 4113 4114 if (++flush_cnt == 10 || 4115 (flush_cnt % 100 == 0 && flush_cnt <= 1000)) 4116 pr_warn("workqueue %s: %s() isn't complete after %u tries\n", 4117 wq->name, __func__, flush_cnt); 4118 4119 mutex_unlock(&wq->mutex); 4120 goto reflush; 4121 } 4122 4123 if (!--wq->nr_drainers) 4124 wq->flags &= ~__WQ_DRAINING; 4125 mutex_unlock(&wq->mutex); 4126 } 4127 EXPORT_SYMBOL_GPL(drain_workqueue); 4128 4129 static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr, 4130 bool from_cancel) 4131 { 4132 struct worker *worker = NULL; 4133 struct worker_pool *pool; 4134 struct pool_workqueue *pwq; 4135 struct workqueue_struct *wq; 4136 4137 rcu_read_lock(); 4138 pool = get_work_pool(work); 4139 if (!pool) { 4140 rcu_read_unlock(); 4141 return false; 4142 } 4143 4144 raw_spin_lock_irq(&pool->lock); 4145 /* see the comment in try_to_grab_pending() with the same code */ 4146 pwq = get_work_pwq(work); 4147 if (pwq) { 4148 if (unlikely(pwq->pool != pool)) 4149 goto already_gone; 4150 } else { 4151 worker = find_worker_executing_work(pool, work); 4152 if (!worker) 4153 goto already_gone; 4154 pwq = worker->current_pwq; 4155 } 4156 4157 wq = pwq->wq; 4158 check_flush_dependency(wq, work); 4159 4160 insert_wq_barrier(pwq, barr, work, worker); 4161 raw_spin_unlock_irq(&pool->lock); 4162 4163 touch_work_lockdep_map(work, wq); 4164 4165 /* 4166 * Force a lock recursion deadlock when using flush_work() inside a 4167 * single-threaded or rescuer equipped workqueue. 4168 * 4169 * For single threaded workqueues the deadlock happens when the work 4170 * is after the work issuing the flush_work(). For rescuer equipped 4171 * workqueues the deadlock happens when the rescuer stalls, blocking 4172 * forward progress. 4173 */ 4174 if (!from_cancel && (wq->saved_max_active == 1 || wq->rescuer)) 4175 touch_wq_lockdep_map(wq); 4176 4177 rcu_read_unlock(); 4178 return true; 4179 already_gone: 4180 raw_spin_unlock_irq(&pool->lock); 4181 rcu_read_unlock(); 4182 return false; 4183 } 4184 4185 static bool __flush_work(struct work_struct *work, bool from_cancel) 4186 { 4187 struct wq_barrier barr; 4188 4189 if (WARN_ON(!wq_online)) 4190 return false; 4191 4192 if (WARN_ON(!work->func)) 4193 return false; 4194 4195 if (!start_flush_work(work, &barr, from_cancel)) 4196 return false; 4197 4198 /* 4199 * start_flush_work() returned %true. If @from_cancel is set, we know 4200 * that @work must have been executing during start_flush_work() and 4201 * can't currently be queued. Its data must contain OFFQ bits. If @work 4202 * was queued on a BH workqueue, we also know that it was running in the 4203 * BH context and thus can be busy-waited. 4204 */ 4205 if (from_cancel) { 4206 unsigned long data = *work_data_bits(work); 4207 4208 if (!WARN_ON_ONCE(data & WORK_STRUCT_PWQ) && 4209 (data & WORK_OFFQ_BH)) { 4210 /* 4211 * On RT, prevent a live lock when %current preempted 4212 * soft interrupt processing or prevents ksoftirqd from 4213 * running by keeping flipping BH. If the BH work item 4214 * runs on a different CPU then this has no effect other 4215 * than doing the BH disable/enable dance for nothing. 4216 * This is copied from 4217 * kernel/softirq.c::tasklet_unlock_spin_wait(). 4218 */ 4219 while (!try_wait_for_completion(&barr.done)) { 4220 if (IS_ENABLED(CONFIG_PREEMPT_RT)) { 4221 local_bh_disable(); 4222 local_bh_enable(); 4223 } else { 4224 cpu_relax(); 4225 } 4226 } 4227 goto out_destroy; 4228 } 4229 } 4230 4231 wait_for_completion(&barr.done); 4232 4233 out_destroy: 4234 destroy_work_on_stack(&barr.work); 4235 return true; 4236 } 4237 4238 /** 4239 * flush_work - wait for a work to finish executing the last queueing instance 4240 * @work: the work to flush 4241 * 4242 * Wait until @work has finished execution. @work is guaranteed to be idle 4243 * on return if it hasn't been requeued since flush started. 4244 * 4245 * Return: 4246 * %true if flush_work() waited for the work to finish execution, 4247 * %false if it was already idle. 4248 */ 4249 bool flush_work(struct work_struct *work) 4250 { 4251 might_sleep(); 4252 return __flush_work(work, false); 4253 } 4254 EXPORT_SYMBOL_GPL(flush_work); 4255 4256 /** 4257 * flush_delayed_work - wait for a dwork to finish executing the last queueing 4258 * @dwork: the delayed work to flush 4259 * 4260 * Delayed timer is cancelled and the pending work is queued for 4261 * immediate execution. Like flush_work(), this function only 4262 * considers the last queueing instance of @dwork. 4263 * 4264 * Return: 4265 * %true if flush_work() waited for the work to finish execution, 4266 * %false if it was already idle. 4267 */ 4268 bool flush_delayed_work(struct delayed_work *dwork) 4269 { 4270 local_irq_disable(); 4271 if (del_timer_sync(&dwork->timer)) 4272 __queue_work(dwork->cpu, dwork->wq, &dwork->work); 4273 local_irq_enable(); 4274 return flush_work(&dwork->work); 4275 } 4276 EXPORT_SYMBOL(flush_delayed_work); 4277 4278 /** 4279 * flush_rcu_work - wait for a rwork to finish executing the last queueing 4280 * @rwork: the rcu work to flush 4281 * 4282 * Return: 4283 * %true if flush_rcu_work() waited for the work to finish execution, 4284 * %false if it was already idle. 4285 */ 4286 bool flush_rcu_work(struct rcu_work *rwork) 4287 { 4288 if (test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&rwork->work))) { 4289 rcu_barrier(); 4290 flush_work(&rwork->work); 4291 return true; 4292 } else { 4293 return flush_work(&rwork->work); 4294 } 4295 } 4296 EXPORT_SYMBOL(flush_rcu_work); 4297 4298 static void work_offqd_disable(struct work_offq_data *offqd) 4299 { 4300 const unsigned long max = (1lu << WORK_OFFQ_DISABLE_BITS) - 1; 4301 4302 if (likely(offqd->disable < max)) 4303 offqd->disable++; 4304 else 4305 WARN_ONCE(true, "workqueue: work disable count overflowed\n"); 4306 } 4307 4308 static void work_offqd_enable(struct work_offq_data *offqd) 4309 { 4310 if (likely(offqd->disable > 0)) 4311 offqd->disable--; 4312 else 4313 WARN_ONCE(true, "workqueue: work disable count underflowed\n"); 4314 } 4315 4316 static bool __cancel_work(struct work_struct *work, u32 cflags) 4317 { 4318 struct work_offq_data offqd; 4319 unsigned long irq_flags; 4320 int ret; 4321 4322 ret = work_grab_pending(work, cflags, &irq_flags); 4323 4324 work_offqd_unpack(&offqd, *work_data_bits(work)); 4325 4326 if (cflags & WORK_CANCEL_DISABLE) 4327 work_offqd_disable(&offqd); 4328 4329 set_work_pool_and_clear_pending(work, offqd.pool_id, 4330 work_offqd_pack_flags(&offqd)); 4331 local_irq_restore(irq_flags); 4332 return ret; 4333 } 4334 4335 static bool __cancel_work_sync(struct work_struct *work, u32 cflags) 4336 { 4337 bool ret; 4338 4339 ret = __cancel_work(work, cflags | WORK_CANCEL_DISABLE); 4340 4341 if (*work_data_bits(work) & WORK_OFFQ_BH) 4342 WARN_ON_ONCE(in_hardirq()); 4343 else 4344 might_sleep(); 4345 4346 /* 4347 * Skip __flush_work() during early boot when we know that @work isn't 4348 * executing. This allows canceling during early boot. 4349 */ 4350 if (wq_online) 4351 __flush_work(work, true); 4352 4353 if (!(cflags & WORK_CANCEL_DISABLE)) 4354 enable_work(work); 4355 4356 return ret; 4357 } 4358 4359 /* 4360 * See cancel_delayed_work() 4361 */ 4362 bool cancel_work(struct work_struct *work) 4363 { 4364 return __cancel_work(work, 0); 4365 } 4366 EXPORT_SYMBOL(cancel_work); 4367 4368 /** 4369 * cancel_work_sync - cancel a work and wait for it to finish 4370 * @work: the work to cancel 4371 * 4372 * Cancel @work and wait for its execution to finish. This function can be used 4373 * even if the work re-queues itself or migrates to another workqueue. On return 4374 * from this function, @work is guaranteed to be not pending or executing on any 4375 * CPU as long as there aren't racing enqueues. 4376 * 4377 * cancel_work_sync(&delayed_work->work) must not be used for delayed_work's. 4378 * Use cancel_delayed_work_sync() instead. 4379 * 4380 * Must be called from a sleepable context if @work was last queued on a non-BH 4381 * workqueue. Can also be called from non-hardirq atomic contexts including BH 4382 * if @work was last queued on a BH workqueue. 4383 * 4384 * Returns %true if @work was pending, %false otherwise. 4385 */ 4386 bool cancel_work_sync(struct work_struct *work) 4387 { 4388 return __cancel_work_sync(work, 0); 4389 } 4390 EXPORT_SYMBOL_GPL(cancel_work_sync); 4391 4392 /** 4393 * cancel_delayed_work - cancel a delayed work 4394 * @dwork: delayed_work to cancel 4395 * 4396 * Kill off a pending delayed_work. 4397 * 4398 * Return: %true if @dwork was pending and canceled; %false if it wasn't 4399 * pending. 4400 * 4401 * Note: 4402 * The work callback function may still be running on return, unless 4403 * it returns %true and the work doesn't re-arm itself. Explicitly flush or 4404 * use cancel_delayed_work_sync() to wait on it. 4405 * 4406 * This function is safe to call from any context including IRQ handler. 4407 */ 4408 bool cancel_delayed_work(struct delayed_work *dwork) 4409 { 4410 return __cancel_work(&dwork->work, WORK_CANCEL_DELAYED); 4411 } 4412 EXPORT_SYMBOL(cancel_delayed_work); 4413 4414 /** 4415 * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish 4416 * @dwork: the delayed work cancel 4417 * 4418 * This is cancel_work_sync() for delayed works. 4419 * 4420 * Return: 4421 * %true if @dwork was pending, %false otherwise. 4422 */ 4423 bool cancel_delayed_work_sync(struct delayed_work *dwork) 4424 { 4425 return __cancel_work_sync(&dwork->work, WORK_CANCEL_DELAYED); 4426 } 4427 EXPORT_SYMBOL(cancel_delayed_work_sync); 4428 4429 /** 4430 * disable_work - Disable and cancel a work item 4431 * @work: work item to disable 4432 * 4433 * Disable @work by incrementing its disable count and cancel it if currently 4434 * pending. As long as the disable count is non-zero, any attempt to queue @work 4435 * will fail and return %false. The maximum supported disable depth is 2 to the 4436 * power of %WORK_OFFQ_DISABLE_BITS, currently 65536. 4437 * 4438 * Can be called from any context. Returns %true if @work was pending, %false 4439 * otherwise. 4440 */ 4441 bool disable_work(struct work_struct *work) 4442 { 4443 return __cancel_work(work, WORK_CANCEL_DISABLE); 4444 } 4445 EXPORT_SYMBOL_GPL(disable_work); 4446 4447 /** 4448 * disable_work_sync - Disable, cancel and drain a work item 4449 * @work: work item to disable 4450 * 4451 * Similar to disable_work() but also wait for @work to finish if currently 4452 * executing. 4453 * 4454 * Must be called from a sleepable context if @work was last queued on a non-BH 4455 * workqueue. Can also be called from non-hardirq atomic contexts including BH 4456 * if @work was last queued on a BH workqueue. 4457 * 4458 * Returns %true if @work was pending, %false otherwise. 4459 */ 4460 bool disable_work_sync(struct work_struct *work) 4461 { 4462 return __cancel_work_sync(work, WORK_CANCEL_DISABLE); 4463 } 4464 EXPORT_SYMBOL_GPL(disable_work_sync); 4465 4466 /** 4467 * enable_work - Enable a work item 4468 * @work: work item to enable 4469 * 4470 * Undo disable_work[_sync]() by decrementing @work's disable count. @work can 4471 * only be queued if its disable count is 0. 4472 * 4473 * Can be called from any context. Returns %true if the disable count reached 0. 4474 * Otherwise, %false. 4475 */ 4476 bool enable_work(struct work_struct *work) 4477 { 4478 struct work_offq_data offqd; 4479 unsigned long irq_flags; 4480 4481 work_grab_pending(work, 0, &irq_flags); 4482 4483 work_offqd_unpack(&offqd, *work_data_bits(work)); 4484 work_offqd_enable(&offqd); 4485 set_work_pool_and_clear_pending(work, offqd.pool_id, 4486 work_offqd_pack_flags(&offqd)); 4487 local_irq_restore(irq_flags); 4488 4489 return !offqd.disable; 4490 } 4491 EXPORT_SYMBOL_GPL(enable_work); 4492 4493 /** 4494 * disable_delayed_work - Disable and cancel a delayed work item 4495 * @dwork: delayed work item to disable 4496 * 4497 * disable_work() for delayed work items. 4498 */ 4499 bool disable_delayed_work(struct delayed_work *dwork) 4500 { 4501 return __cancel_work(&dwork->work, 4502 WORK_CANCEL_DELAYED | WORK_CANCEL_DISABLE); 4503 } 4504 EXPORT_SYMBOL_GPL(disable_delayed_work); 4505 4506 /** 4507 * disable_delayed_work_sync - Disable, cancel and drain a delayed work item 4508 * @dwork: delayed work item to disable 4509 * 4510 * disable_work_sync() for delayed work items. 4511 */ 4512 bool disable_delayed_work_sync(struct delayed_work *dwork) 4513 { 4514 return __cancel_work_sync(&dwork->work, 4515 WORK_CANCEL_DELAYED | WORK_CANCEL_DISABLE); 4516 } 4517 EXPORT_SYMBOL_GPL(disable_delayed_work_sync); 4518 4519 /** 4520 * enable_delayed_work - Enable a delayed work item 4521 * @dwork: delayed work item to enable 4522 * 4523 * enable_work() for delayed work items. 4524 */ 4525 bool enable_delayed_work(struct delayed_work *dwork) 4526 { 4527 return enable_work(&dwork->work); 4528 } 4529 EXPORT_SYMBOL_GPL(enable_delayed_work); 4530 4531 /** 4532 * schedule_on_each_cpu - execute a function synchronously on each online CPU 4533 * @func: the function to call 4534 * 4535 * schedule_on_each_cpu() executes @func on each online CPU using the 4536 * system workqueue and blocks until all CPUs have completed. 4537 * schedule_on_each_cpu() is very slow. 4538 * 4539 * Return: 4540 * 0 on success, -errno on failure. 4541 */ 4542 int schedule_on_each_cpu(work_func_t func) 4543 { 4544 int cpu; 4545 struct work_struct __percpu *works; 4546 4547 works = alloc_percpu(struct work_struct); 4548 if (!works) 4549 return -ENOMEM; 4550 4551 cpus_read_lock(); 4552 4553 for_each_online_cpu(cpu) { 4554 struct work_struct *work = per_cpu_ptr(works, cpu); 4555 4556 INIT_WORK(work, func); 4557 schedule_work_on(cpu, work); 4558 } 4559 4560 for_each_online_cpu(cpu) 4561 flush_work(per_cpu_ptr(works, cpu)); 4562 4563 cpus_read_unlock(); 4564 free_percpu(works); 4565 return 0; 4566 } 4567 4568 /** 4569 * execute_in_process_context - reliably execute the routine with user context 4570 * @fn: the function to execute 4571 * @ew: guaranteed storage for the execute work structure (must 4572 * be available when the work executes) 4573 * 4574 * Executes the function immediately if process context is available, 4575 * otherwise schedules the function for delayed execution. 4576 * 4577 * Return: 0 - function was executed 4578 * 1 - function was scheduled for execution 4579 */ 4580 int execute_in_process_context(work_func_t fn, struct execute_work *ew) 4581 { 4582 if (!in_interrupt()) { 4583 fn(&ew->work); 4584 return 0; 4585 } 4586 4587 INIT_WORK(&ew->work, fn); 4588 schedule_work(&ew->work); 4589 4590 return 1; 4591 } 4592 EXPORT_SYMBOL_GPL(execute_in_process_context); 4593 4594 /** 4595 * free_workqueue_attrs - free a workqueue_attrs 4596 * @attrs: workqueue_attrs to free 4597 * 4598 * Undo alloc_workqueue_attrs(). 4599 */ 4600 void free_workqueue_attrs(struct workqueue_attrs *attrs) 4601 { 4602 if (attrs) { 4603 free_cpumask_var(attrs->cpumask); 4604 free_cpumask_var(attrs->__pod_cpumask); 4605 kfree(attrs); 4606 } 4607 } 4608 4609 /** 4610 * alloc_workqueue_attrs - allocate a workqueue_attrs 4611 * 4612 * Allocate a new workqueue_attrs, initialize with default settings and 4613 * return it. 4614 * 4615 * Return: The allocated new workqueue_attr on success. %NULL on failure. 4616 */ 4617 struct workqueue_attrs *alloc_workqueue_attrs(void) 4618 { 4619 struct workqueue_attrs *attrs; 4620 4621 attrs = kzalloc(sizeof(*attrs), GFP_KERNEL); 4622 if (!attrs) 4623 goto fail; 4624 if (!alloc_cpumask_var(&attrs->cpumask, GFP_KERNEL)) 4625 goto fail; 4626 if (!alloc_cpumask_var(&attrs->__pod_cpumask, GFP_KERNEL)) 4627 goto fail; 4628 4629 cpumask_copy(attrs->cpumask, cpu_possible_mask); 4630 attrs->affn_scope = WQ_AFFN_DFL; 4631 return attrs; 4632 fail: 4633 free_workqueue_attrs(attrs); 4634 return NULL; 4635 } 4636 4637 static void copy_workqueue_attrs(struct workqueue_attrs *to, 4638 const struct workqueue_attrs *from) 4639 { 4640 to->nice = from->nice; 4641 cpumask_copy(to->cpumask, from->cpumask); 4642 cpumask_copy(to->__pod_cpumask, from->__pod_cpumask); 4643 to->affn_strict = from->affn_strict; 4644 4645 /* 4646 * Unlike hash and equality test, copying shouldn't ignore wq-only 4647 * fields as copying is used for both pool and wq attrs. Instead, 4648 * get_unbound_pool() explicitly clears the fields. 4649 */ 4650 to->affn_scope = from->affn_scope; 4651 to->ordered = from->ordered; 4652 } 4653 4654 /* 4655 * Some attrs fields are workqueue-only. Clear them for worker_pool's. See the 4656 * comments in 'struct workqueue_attrs' definition. 4657 */ 4658 static void wqattrs_clear_for_pool(struct workqueue_attrs *attrs) 4659 { 4660 attrs->affn_scope = WQ_AFFN_NR_TYPES; 4661 attrs->ordered = false; 4662 if (attrs->affn_strict) 4663 cpumask_copy(attrs->cpumask, cpu_possible_mask); 4664 } 4665 4666 /* hash value of the content of @attr */ 4667 static u32 wqattrs_hash(const struct workqueue_attrs *attrs) 4668 { 4669 u32 hash = 0; 4670 4671 hash = jhash_1word(attrs->nice, hash); 4672 hash = jhash_1word(attrs->affn_strict, hash); 4673 hash = jhash(cpumask_bits(attrs->__pod_cpumask), 4674 BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash); 4675 if (!attrs->affn_strict) 4676 hash = jhash(cpumask_bits(attrs->cpumask), 4677 BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash); 4678 return hash; 4679 } 4680 4681 /* content equality test */ 4682 static bool wqattrs_equal(const struct workqueue_attrs *a, 4683 const struct workqueue_attrs *b) 4684 { 4685 if (a->nice != b->nice) 4686 return false; 4687 if (a->affn_strict != b->affn_strict) 4688 return false; 4689 if (!cpumask_equal(a->__pod_cpumask, b->__pod_cpumask)) 4690 return false; 4691 if (!a->affn_strict && !cpumask_equal(a->cpumask, b->cpumask)) 4692 return false; 4693 return true; 4694 } 4695 4696 /* Update @attrs with actually available CPUs */ 4697 static void wqattrs_actualize_cpumask(struct workqueue_attrs *attrs, 4698 const cpumask_t *unbound_cpumask) 4699 { 4700 /* 4701 * Calculate the effective CPU mask of @attrs given @unbound_cpumask. If 4702 * @attrs->cpumask doesn't overlap with @unbound_cpumask, we fallback to 4703 * @unbound_cpumask. 4704 */ 4705 cpumask_and(attrs->cpumask, attrs->cpumask, unbound_cpumask); 4706 if (unlikely(cpumask_empty(attrs->cpumask))) 4707 cpumask_copy(attrs->cpumask, unbound_cpumask); 4708 } 4709 4710 /* find wq_pod_type to use for @attrs */ 4711 static const struct wq_pod_type * 4712 wqattrs_pod_type(const struct workqueue_attrs *attrs) 4713 { 4714 enum wq_affn_scope scope; 4715 struct wq_pod_type *pt; 4716 4717 /* to synchronize access to wq_affn_dfl */ 4718 lockdep_assert_held(&wq_pool_mutex); 4719 4720 if (attrs->affn_scope == WQ_AFFN_DFL) 4721 scope = wq_affn_dfl; 4722 else 4723 scope = attrs->affn_scope; 4724 4725 pt = &wq_pod_types[scope]; 4726 4727 if (!WARN_ON_ONCE(attrs->affn_scope == WQ_AFFN_NR_TYPES) && 4728 likely(pt->nr_pods)) 4729 return pt; 4730 4731 /* 4732 * Before workqueue_init_topology(), only SYSTEM is available which is 4733 * initialized in workqueue_init_early(). 4734 */ 4735 pt = &wq_pod_types[WQ_AFFN_SYSTEM]; 4736 BUG_ON(!pt->nr_pods); 4737 return pt; 4738 } 4739 4740 /** 4741 * init_worker_pool - initialize a newly zalloc'd worker_pool 4742 * @pool: worker_pool to initialize 4743 * 4744 * Initialize a newly zalloc'd @pool. It also allocates @pool->attrs. 4745 * 4746 * Return: 0 on success, -errno on failure. Even on failure, all fields 4747 * inside @pool proper are initialized and put_unbound_pool() can be called 4748 * on @pool safely to release it. 4749 */ 4750 static int init_worker_pool(struct worker_pool *pool) 4751 { 4752 raw_spin_lock_init(&pool->lock); 4753 pool->id = -1; 4754 pool->cpu = -1; 4755 pool->node = NUMA_NO_NODE; 4756 pool->flags |= POOL_DISASSOCIATED; 4757 pool->watchdog_ts = jiffies; 4758 INIT_LIST_HEAD(&pool->worklist); 4759 INIT_LIST_HEAD(&pool->idle_list); 4760 hash_init(pool->busy_hash); 4761 4762 timer_setup(&pool->idle_timer, idle_worker_timeout, TIMER_DEFERRABLE); 4763 INIT_WORK(&pool->idle_cull_work, idle_cull_fn); 4764 4765 timer_setup(&pool->mayday_timer, pool_mayday_timeout, 0); 4766 4767 INIT_LIST_HEAD(&pool->workers); 4768 4769 ida_init(&pool->worker_ida); 4770 INIT_HLIST_NODE(&pool->hash_node); 4771 pool->refcnt = 1; 4772 4773 /* shouldn't fail above this point */ 4774 pool->attrs = alloc_workqueue_attrs(); 4775 if (!pool->attrs) 4776 return -ENOMEM; 4777 4778 wqattrs_clear_for_pool(pool->attrs); 4779 4780 return 0; 4781 } 4782 4783 #ifdef CONFIG_LOCKDEP 4784 static void wq_init_lockdep(struct workqueue_struct *wq) 4785 { 4786 char *lock_name; 4787 4788 lockdep_register_key(&wq->key); 4789 lock_name = kasprintf(GFP_KERNEL, "%s%s", "(wq_completion)", wq->name); 4790 if (!lock_name) 4791 lock_name = wq->name; 4792 4793 wq->lock_name = lock_name; 4794 wq->lockdep_map = &wq->__lockdep_map; 4795 lockdep_init_map(wq->lockdep_map, lock_name, &wq->key, 0); 4796 } 4797 4798 static void wq_unregister_lockdep(struct workqueue_struct *wq) 4799 { 4800 if (wq->lockdep_map != &wq->__lockdep_map) 4801 return; 4802 4803 lockdep_unregister_key(&wq->key); 4804 } 4805 4806 static void wq_free_lockdep(struct workqueue_struct *wq) 4807 { 4808 if (wq->lockdep_map != &wq->__lockdep_map) 4809 return; 4810 4811 if (wq->lock_name != wq->name) 4812 kfree(wq->lock_name); 4813 } 4814 #else 4815 static void wq_init_lockdep(struct workqueue_struct *wq) 4816 { 4817 } 4818 4819 static void wq_unregister_lockdep(struct workqueue_struct *wq) 4820 { 4821 } 4822 4823 static void wq_free_lockdep(struct workqueue_struct *wq) 4824 { 4825 } 4826 #endif 4827 4828 static void free_node_nr_active(struct wq_node_nr_active **nna_ar) 4829 { 4830 int node; 4831 4832 for_each_node(node) { 4833 kfree(nna_ar[node]); 4834 nna_ar[node] = NULL; 4835 } 4836 4837 kfree(nna_ar[nr_node_ids]); 4838 nna_ar[nr_node_ids] = NULL; 4839 } 4840 4841 static void init_node_nr_active(struct wq_node_nr_active *nna) 4842 { 4843 nna->max = WQ_DFL_MIN_ACTIVE; 4844 atomic_set(&nna->nr, 0); 4845 raw_spin_lock_init(&nna->lock); 4846 INIT_LIST_HEAD(&nna->pending_pwqs); 4847 } 4848 4849 /* 4850 * Each node's nr_active counter will be accessed mostly from its own node and 4851 * should be allocated in the node. 4852 */ 4853 static int alloc_node_nr_active(struct wq_node_nr_active **nna_ar) 4854 { 4855 struct wq_node_nr_active *nna; 4856 int node; 4857 4858 for_each_node(node) { 4859 nna = kzalloc_node(sizeof(*nna), GFP_KERNEL, node); 4860 if (!nna) 4861 goto err_free; 4862 init_node_nr_active(nna); 4863 nna_ar[node] = nna; 4864 } 4865 4866 /* [nr_node_ids] is used as the fallback */ 4867 nna = kzalloc_node(sizeof(*nna), GFP_KERNEL, NUMA_NO_NODE); 4868 if (!nna) 4869 goto err_free; 4870 init_node_nr_active(nna); 4871 nna_ar[nr_node_ids] = nna; 4872 4873 return 0; 4874 4875 err_free: 4876 free_node_nr_active(nna_ar); 4877 return -ENOMEM; 4878 } 4879 4880 static void rcu_free_wq(struct rcu_head *rcu) 4881 { 4882 struct workqueue_struct *wq = 4883 container_of(rcu, struct workqueue_struct, rcu); 4884 4885 if (wq->flags & WQ_UNBOUND) 4886 free_node_nr_active(wq->node_nr_active); 4887 4888 wq_free_lockdep(wq); 4889 free_percpu(wq->cpu_pwq); 4890 free_workqueue_attrs(wq->unbound_attrs); 4891 kfree(wq); 4892 } 4893 4894 static void rcu_free_pool(struct rcu_head *rcu) 4895 { 4896 struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu); 4897 4898 ida_destroy(&pool->worker_ida); 4899 free_workqueue_attrs(pool->attrs); 4900 kfree(pool); 4901 } 4902 4903 /** 4904 * put_unbound_pool - put a worker_pool 4905 * @pool: worker_pool to put 4906 * 4907 * Put @pool. If its refcnt reaches zero, it gets destroyed in RCU 4908 * safe manner. get_unbound_pool() calls this function on its failure path 4909 * and this function should be able to release pools which went through, 4910 * successfully or not, init_worker_pool(). 4911 * 4912 * Should be called with wq_pool_mutex held. 4913 */ 4914 static void put_unbound_pool(struct worker_pool *pool) 4915 { 4916 struct worker *worker; 4917 LIST_HEAD(cull_list); 4918 4919 lockdep_assert_held(&wq_pool_mutex); 4920 4921 if (--pool->refcnt) 4922 return; 4923 4924 /* sanity checks */ 4925 if (WARN_ON(!(pool->cpu < 0)) || 4926 WARN_ON(!list_empty(&pool->worklist))) 4927 return; 4928 4929 /* release id and unhash */ 4930 if (pool->id >= 0) 4931 idr_remove(&worker_pool_idr, pool->id); 4932 hash_del(&pool->hash_node); 4933 4934 /* 4935 * Become the manager and destroy all workers. This prevents 4936 * @pool's workers from blocking on attach_mutex. We're the last 4937 * manager and @pool gets freed with the flag set. 4938 * 4939 * Having a concurrent manager is quite unlikely to happen as we can 4940 * only get here with 4941 * pwq->refcnt == pool->refcnt == 0 4942 * which implies no work queued to the pool, which implies no worker can 4943 * become the manager. However a worker could have taken the role of 4944 * manager before the refcnts dropped to 0, since maybe_create_worker() 4945 * drops pool->lock 4946 */ 4947 while (true) { 4948 rcuwait_wait_event(&manager_wait, 4949 !(pool->flags & POOL_MANAGER_ACTIVE), 4950 TASK_UNINTERRUPTIBLE); 4951 4952 mutex_lock(&wq_pool_attach_mutex); 4953 raw_spin_lock_irq(&pool->lock); 4954 if (!(pool->flags & POOL_MANAGER_ACTIVE)) { 4955 pool->flags |= POOL_MANAGER_ACTIVE; 4956 break; 4957 } 4958 raw_spin_unlock_irq(&pool->lock); 4959 mutex_unlock(&wq_pool_attach_mutex); 4960 } 4961 4962 while ((worker = first_idle_worker(pool))) 4963 set_worker_dying(worker, &cull_list); 4964 WARN_ON(pool->nr_workers || pool->nr_idle); 4965 raw_spin_unlock_irq(&pool->lock); 4966 4967 detach_dying_workers(&cull_list); 4968 4969 mutex_unlock(&wq_pool_attach_mutex); 4970 4971 reap_dying_workers(&cull_list); 4972 4973 /* shut down the timers */ 4974 del_timer_sync(&pool->idle_timer); 4975 cancel_work_sync(&pool->idle_cull_work); 4976 del_timer_sync(&pool->mayday_timer); 4977 4978 /* RCU protected to allow dereferences from get_work_pool() */ 4979 call_rcu(&pool->rcu, rcu_free_pool); 4980 } 4981 4982 /** 4983 * get_unbound_pool - get a worker_pool with the specified attributes 4984 * @attrs: the attributes of the worker_pool to get 4985 * 4986 * Obtain a worker_pool which has the same attributes as @attrs, bump the 4987 * reference count and return it. If there already is a matching 4988 * worker_pool, it will be used; otherwise, this function attempts to 4989 * create a new one. 4990 * 4991 * Should be called with wq_pool_mutex held. 4992 * 4993 * Return: On success, a worker_pool with the same attributes as @attrs. 4994 * On failure, %NULL. 4995 */ 4996 static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) 4997 { 4998 struct wq_pod_type *pt = &wq_pod_types[WQ_AFFN_NUMA]; 4999 u32 hash = wqattrs_hash(attrs); 5000 struct worker_pool *pool; 5001 int pod, node = NUMA_NO_NODE; 5002 5003 lockdep_assert_held(&wq_pool_mutex); 5004 5005 /* do we already have a matching pool? */ 5006 hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) { 5007 if (wqattrs_equal(pool->attrs, attrs)) { 5008 pool->refcnt++; 5009 return pool; 5010 } 5011 } 5012 5013 /* If __pod_cpumask is contained inside a NUMA pod, that's our node */ 5014 for (pod = 0; pod < pt->nr_pods; pod++) { 5015 if (cpumask_subset(attrs->__pod_cpumask, pt->pod_cpus[pod])) { 5016 node = pt->pod_node[pod]; 5017 break; 5018 } 5019 } 5020 5021 /* nope, create a new one */ 5022 pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, node); 5023 if (!pool || init_worker_pool(pool) < 0) 5024 goto fail; 5025 5026 pool->node = node; 5027 copy_workqueue_attrs(pool->attrs, attrs); 5028 wqattrs_clear_for_pool(pool->attrs); 5029 5030 if (worker_pool_assign_id(pool) < 0) 5031 goto fail; 5032 5033 /* create and start the initial worker */ 5034 if (wq_online && !create_worker(pool)) 5035 goto fail; 5036 5037 /* install */ 5038 hash_add(unbound_pool_hash, &pool->hash_node, hash); 5039 5040 return pool; 5041 fail: 5042 if (pool) 5043 put_unbound_pool(pool); 5044 return NULL; 5045 } 5046 5047 /* 5048 * Scheduled on pwq_release_worker by put_pwq() when an unbound pwq hits zero 5049 * refcnt and needs to be destroyed. 5050 */ 5051 static void pwq_release_workfn(struct kthread_work *work) 5052 { 5053 struct pool_workqueue *pwq = container_of(work, struct pool_workqueue, 5054 release_work); 5055 struct workqueue_struct *wq = pwq->wq; 5056 struct worker_pool *pool = pwq->pool; 5057 bool is_last = false; 5058 5059 /* 5060 * When @pwq is not linked, it doesn't hold any reference to the 5061 * @wq, and @wq is invalid to access. 5062 */ 5063 if (!list_empty(&pwq->pwqs_node)) { 5064 mutex_lock(&wq->mutex); 5065 list_del_rcu(&pwq->pwqs_node); 5066 is_last = list_empty(&wq->pwqs); 5067 5068 /* 5069 * For ordered workqueue with a plugged dfl_pwq, restart it now. 5070 */ 5071 if (!is_last && (wq->flags & __WQ_ORDERED)) 5072 unplug_oldest_pwq(wq); 5073 5074 mutex_unlock(&wq->mutex); 5075 } 5076 5077 if (wq->flags & WQ_UNBOUND) { 5078 mutex_lock(&wq_pool_mutex); 5079 put_unbound_pool(pool); 5080 mutex_unlock(&wq_pool_mutex); 5081 } 5082 5083 if (!list_empty(&pwq->pending_node)) { 5084 struct wq_node_nr_active *nna = 5085 wq_node_nr_active(pwq->wq, pwq->pool->node); 5086 5087 raw_spin_lock_irq(&nna->lock); 5088 list_del_init(&pwq->pending_node); 5089 raw_spin_unlock_irq(&nna->lock); 5090 } 5091 5092 kfree_rcu(pwq, rcu); 5093 5094 /* 5095 * If we're the last pwq going away, @wq is already dead and no one 5096 * is gonna access it anymore. Schedule RCU free. 5097 */ 5098 if (is_last) { 5099 wq_unregister_lockdep(wq); 5100 call_rcu(&wq->rcu, rcu_free_wq); 5101 } 5102 } 5103 5104 /* initialize newly allocated @pwq which is associated with @wq and @pool */ 5105 static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq, 5106 struct worker_pool *pool) 5107 { 5108 BUG_ON((unsigned long)pwq & ~WORK_STRUCT_PWQ_MASK); 5109 5110 memset(pwq, 0, sizeof(*pwq)); 5111 5112 pwq->pool = pool; 5113 pwq->wq = wq; 5114 pwq->flush_color = -1; 5115 pwq->refcnt = 1; 5116 INIT_LIST_HEAD(&pwq->inactive_works); 5117 INIT_LIST_HEAD(&pwq->pending_node); 5118 INIT_LIST_HEAD(&pwq->pwqs_node); 5119 INIT_LIST_HEAD(&pwq->mayday_node); 5120 kthread_init_work(&pwq->release_work, pwq_release_workfn); 5121 } 5122 5123 /* sync @pwq with the current state of its associated wq and link it */ 5124 static void link_pwq(struct pool_workqueue *pwq) 5125 { 5126 struct workqueue_struct *wq = pwq->wq; 5127 5128 lockdep_assert_held(&wq->mutex); 5129 5130 /* may be called multiple times, ignore if already linked */ 5131 if (!list_empty(&pwq->pwqs_node)) 5132 return; 5133 5134 /* set the matching work_color */ 5135 pwq->work_color = wq->work_color; 5136 5137 /* link in @pwq */ 5138 list_add_tail_rcu(&pwq->pwqs_node, &wq->pwqs); 5139 } 5140 5141 /* obtain a pool matching @attr and create a pwq associating the pool and @wq */ 5142 static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq, 5143 const struct workqueue_attrs *attrs) 5144 { 5145 struct worker_pool *pool; 5146 struct pool_workqueue *pwq; 5147 5148 lockdep_assert_held(&wq_pool_mutex); 5149 5150 pool = get_unbound_pool(attrs); 5151 if (!pool) 5152 return NULL; 5153 5154 pwq = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, pool->node); 5155 if (!pwq) { 5156 put_unbound_pool(pool); 5157 return NULL; 5158 } 5159 5160 init_pwq(pwq, wq, pool); 5161 return pwq; 5162 } 5163 5164 static void apply_wqattrs_lock(void) 5165 { 5166 mutex_lock(&wq_pool_mutex); 5167 } 5168 5169 static void apply_wqattrs_unlock(void) 5170 { 5171 mutex_unlock(&wq_pool_mutex); 5172 } 5173 5174 /** 5175 * wq_calc_pod_cpumask - calculate a wq_attrs' cpumask for a pod 5176 * @attrs: the wq_attrs of the default pwq of the target workqueue 5177 * @cpu: the target CPU 5178 * 5179 * Calculate the cpumask a workqueue with @attrs should use on @pod. 5180 * The result is stored in @attrs->__pod_cpumask. 5181 * 5182 * If pod affinity is not enabled, @attrs->cpumask is always used. If enabled 5183 * and @pod has online CPUs requested by @attrs, the returned cpumask is the 5184 * intersection of the possible CPUs of @pod and @attrs->cpumask. 5185 * 5186 * The caller is responsible for ensuring that the cpumask of @pod stays stable. 5187 */ 5188 static void wq_calc_pod_cpumask(struct workqueue_attrs *attrs, int cpu) 5189 { 5190 const struct wq_pod_type *pt = wqattrs_pod_type(attrs); 5191 int pod = pt->cpu_pod[cpu]; 5192 5193 /* calculate possible CPUs in @pod that @attrs wants */ 5194 cpumask_and(attrs->__pod_cpumask, pt->pod_cpus[pod], attrs->cpumask); 5195 /* does @pod have any online CPUs @attrs wants? */ 5196 if (!cpumask_intersects(attrs->__pod_cpumask, wq_online_cpumask)) { 5197 cpumask_copy(attrs->__pod_cpumask, attrs->cpumask); 5198 return; 5199 } 5200 } 5201 5202 /* install @pwq into @wq and return the old pwq, @cpu < 0 for dfl_pwq */ 5203 static struct pool_workqueue *install_unbound_pwq(struct workqueue_struct *wq, 5204 int cpu, struct pool_workqueue *pwq) 5205 { 5206 struct pool_workqueue __rcu **slot = unbound_pwq_slot(wq, cpu); 5207 struct pool_workqueue *old_pwq; 5208 5209 lockdep_assert_held(&wq_pool_mutex); 5210 lockdep_assert_held(&wq->mutex); 5211 5212 /* link_pwq() can handle duplicate calls */ 5213 link_pwq(pwq); 5214 5215 old_pwq = rcu_access_pointer(*slot); 5216 rcu_assign_pointer(*slot, pwq); 5217 return old_pwq; 5218 } 5219 5220 /* context to store the prepared attrs & pwqs before applying */ 5221 struct apply_wqattrs_ctx { 5222 struct workqueue_struct *wq; /* target workqueue */ 5223 struct workqueue_attrs *attrs; /* attrs to apply */ 5224 struct list_head list; /* queued for batching commit */ 5225 struct pool_workqueue *dfl_pwq; 5226 struct pool_workqueue *pwq_tbl[]; 5227 }; 5228 5229 /* free the resources after success or abort */ 5230 static void apply_wqattrs_cleanup(struct apply_wqattrs_ctx *ctx) 5231 { 5232 if (ctx) { 5233 int cpu; 5234 5235 for_each_possible_cpu(cpu) 5236 put_pwq_unlocked(ctx->pwq_tbl[cpu]); 5237 put_pwq_unlocked(ctx->dfl_pwq); 5238 5239 free_workqueue_attrs(ctx->attrs); 5240 5241 kfree(ctx); 5242 } 5243 } 5244 5245 /* allocate the attrs and pwqs for later installation */ 5246 static struct apply_wqattrs_ctx * 5247 apply_wqattrs_prepare(struct workqueue_struct *wq, 5248 const struct workqueue_attrs *attrs, 5249 const cpumask_var_t unbound_cpumask) 5250 { 5251 struct apply_wqattrs_ctx *ctx; 5252 struct workqueue_attrs *new_attrs; 5253 int cpu; 5254 5255 lockdep_assert_held(&wq_pool_mutex); 5256 5257 if (WARN_ON(attrs->affn_scope < 0 || 5258 attrs->affn_scope >= WQ_AFFN_NR_TYPES)) 5259 return ERR_PTR(-EINVAL); 5260 5261 ctx = kzalloc(struct_size(ctx, pwq_tbl, nr_cpu_ids), GFP_KERNEL); 5262 5263 new_attrs = alloc_workqueue_attrs(); 5264 if (!ctx || !new_attrs) 5265 goto out_free; 5266 5267 /* 5268 * If something goes wrong during CPU up/down, we'll fall back to 5269 * the default pwq covering whole @attrs->cpumask. Always create 5270 * it even if we don't use it immediately. 5271 */ 5272 copy_workqueue_attrs(new_attrs, attrs); 5273 wqattrs_actualize_cpumask(new_attrs, unbound_cpumask); 5274 cpumask_copy(new_attrs->__pod_cpumask, new_attrs->cpumask); 5275 ctx->dfl_pwq = alloc_unbound_pwq(wq, new_attrs); 5276 if (!ctx->dfl_pwq) 5277 goto out_free; 5278 5279 for_each_possible_cpu(cpu) { 5280 if (new_attrs->ordered) { 5281 ctx->dfl_pwq->refcnt++; 5282 ctx->pwq_tbl[cpu] = ctx->dfl_pwq; 5283 } else { 5284 wq_calc_pod_cpumask(new_attrs, cpu); 5285 ctx->pwq_tbl[cpu] = alloc_unbound_pwq(wq, new_attrs); 5286 if (!ctx->pwq_tbl[cpu]) 5287 goto out_free; 5288 } 5289 } 5290 5291 /* save the user configured attrs and sanitize it. */ 5292 copy_workqueue_attrs(new_attrs, attrs); 5293 cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask); 5294 cpumask_copy(new_attrs->__pod_cpumask, new_attrs->cpumask); 5295 ctx->attrs = new_attrs; 5296 5297 /* 5298 * For initialized ordered workqueues, there should only be one pwq 5299 * (dfl_pwq). Set the plugged flag of ctx->dfl_pwq to suspend execution 5300 * of newly queued work items until execution of older work items in 5301 * the old pwq's have completed. 5302 */ 5303 if ((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs)) 5304 ctx->dfl_pwq->plugged = true; 5305 5306 ctx->wq = wq; 5307 return ctx; 5308 5309 out_free: 5310 free_workqueue_attrs(new_attrs); 5311 apply_wqattrs_cleanup(ctx); 5312 return ERR_PTR(-ENOMEM); 5313 } 5314 5315 /* set attrs and install prepared pwqs, @ctx points to old pwqs on return */ 5316 static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx) 5317 { 5318 int cpu; 5319 5320 /* all pwqs have been created successfully, let's install'em */ 5321 mutex_lock(&ctx->wq->mutex); 5322 5323 copy_workqueue_attrs(ctx->wq->unbound_attrs, ctx->attrs); 5324 5325 /* save the previous pwqs and install the new ones */ 5326 for_each_possible_cpu(cpu) 5327 ctx->pwq_tbl[cpu] = install_unbound_pwq(ctx->wq, cpu, 5328 ctx->pwq_tbl[cpu]); 5329 ctx->dfl_pwq = install_unbound_pwq(ctx->wq, -1, ctx->dfl_pwq); 5330 5331 /* update node_nr_active->max */ 5332 wq_update_node_max_active(ctx->wq, -1); 5333 5334 /* rescuer needs to respect wq cpumask changes */ 5335 if (ctx->wq->rescuer) 5336 set_cpus_allowed_ptr(ctx->wq->rescuer->task, 5337 unbound_effective_cpumask(ctx->wq)); 5338 5339 mutex_unlock(&ctx->wq->mutex); 5340 } 5341 5342 static int apply_workqueue_attrs_locked(struct workqueue_struct *wq, 5343 const struct workqueue_attrs *attrs) 5344 { 5345 struct apply_wqattrs_ctx *ctx; 5346 5347 /* only unbound workqueues can change attributes */ 5348 if (WARN_ON(!(wq->flags & WQ_UNBOUND))) 5349 return -EINVAL; 5350 5351 ctx = apply_wqattrs_prepare(wq, attrs, wq_unbound_cpumask); 5352 if (IS_ERR(ctx)) 5353 return PTR_ERR(ctx); 5354 5355 /* the ctx has been prepared successfully, let's commit it */ 5356 apply_wqattrs_commit(ctx); 5357 apply_wqattrs_cleanup(ctx); 5358 5359 return 0; 5360 } 5361 5362 /** 5363 * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue 5364 * @wq: the target workqueue 5365 * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs() 5366 * 5367 * Apply @attrs to an unbound workqueue @wq. Unless disabled, this function maps 5368 * a separate pwq to each CPU pod with possibles CPUs in @attrs->cpumask so that 5369 * work items are affine to the pod it was issued on. Older pwqs are released as 5370 * in-flight work items finish. Note that a work item which repeatedly requeues 5371 * itself back-to-back will stay on its current pwq. 5372 * 5373 * Performs GFP_KERNEL allocations. 5374 * 5375 * Return: 0 on success and -errno on failure. 5376 */ 5377 int apply_workqueue_attrs(struct workqueue_struct *wq, 5378 const struct workqueue_attrs *attrs) 5379 { 5380 int ret; 5381 5382 mutex_lock(&wq_pool_mutex); 5383 ret = apply_workqueue_attrs_locked(wq, attrs); 5384 mutex_unlock(&wq_pool_mutex); 5385 5386 return ret; 5387 } 5388 5389 /** 5390 * unbound_wq_update_pwq - update a pwq slot for CPU hot[un]plug 5391 * @wq: the target workqueue 5392 * @cpu: the CPU to update the pwq slot for 5393 * 5394 * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and 5395 * %CPU_DOWN_FAILED. @cpu is in the same pod of the CPU being hot[un]plugged. 5396 * 5397 * 5398 * If pod affinity can't be adjusted due to memory allocation failure, it falls 5399 * back to @wq->dfl_pwq which may not be optimal but is always correct. 5400 * 5401 * Note that when the last allowed CPU of a pod goes offline for a workqueue 5402 * with a cpumask spanning multiple pods, the workers which were already 5403 * executing the work items for the workqueue will lose their CPU affinity and 5404 * may execute on any CPU. This is similar to how per-cpu workqueues behave on 5405 * CPU_DOWN. If a workqueue user wants strict affinity, it's the user's 5406 * responsibility to flush the work item from CPU_DOWN_PREPARE. 5407 */ 5408 static void unbound_wq_update_pwq(struct workqueue_struct *wq, int cpu) 5409 { 5410 struct pool_workqueue *old_pwq = NULL, *pwq; 5411 struct workqueue_attrs *target_attrs; 5412 5413 lockdep_assert_held(&wq_pool_mutex); 5414 5415 if (!(wq->flags & WQ_UNBOUND) || wq->unbound_attrs->ordered) 5416 return; 5417 5418 /* 5419 * We don't wanna alloc/free wq_attrs for each wq for each CPU. 5420 * Let's use a preallocated one. The following buf is protected by 5421 * CPU hotplug exclusion. 5422 */ 5423 target_attrs = unbound_wq_update_pwq_attrs_buf; 5424 5425 copy_workqueue_attrs(target_attrs, wq->unbound_attrs); 5426 wqattrs_actualize_cpumask(target_attrs, wq_unbound_cpumask); 5427 5428 /* nothing to do if the target cpumask matches the current pwq */ 5429 wq_calc_pod_cpumask(target_attrs, cpu); 5430 if (wqattrs_equal(target_attrs, unbound_pwq(wq, cpu)->pool->attrs)) 5431 return; 5432 5433 /* create a new pwq */ 5434 pwq = alloc_unbound_pwq(wq, target_attrs); 5435 if (!pwq) { 5436 pr_warn("workqueue: allocation failed while updating CPU pod affinity of \"%s\"\n", 5437 wq->name); 5438 goto use_dfl_pwq; 5439 } 5440 5441 /* Install the new pwq. */ 5442 mutex_lock(&wq->mutex); 5443 old_pwq = install_unbound_pwq(wq, cpu, pwq); 5444 goto out_unlock; 5445 5446 use_dfl_pwq: 5447 mutex_lock(&wq->mutex); 5448 pwq = unbound_pwq(wq, -1); 5449 raw_spin_lock_irq(&pwq->pool->lock); 5450 get_pwq(pwq); 5451 raw_spin_unlock_irq(&pwq->pool->lock); 5452 old_pwq = install_unbound_pwq(wq, cpu, pwq); 5453 out_unlock: 5454 mutex_unlock(&wq->mutex); 5455 put_pwq_unlocked(old_pwq); 5456 } 5457 5458 static int alloc_and_link_pwqs(struct workqueue_struct *wq) 5459 { 5460 bool highpri = wq->flags & WQ_HIGHPRI; 5461 int cpu, ret; 5462 5463 lockdep_assert_held(&wq_pool_mutex); 5464 5465 wq->cpu_pwq = alloc_percpu(struct pool_workqueue *); 5466 if (!wq->cpu_pwq) 5467 goto enomem; 5468 5469 if (!(wq->flags & WQ_UNBOUND)) { 5470 struct worker_pool __percpu *pools; 5471 5472 if (wq->flags & WQ_BH) 5473 pools = bh_worker_pools; 5474 else 5475 pools = cpu_worker_pools; 5476 5477 for_each_possible_cpu(cpu) { 5478 struct pool_workqueue **pwq_p; 5479 struct worker_pool *pool; 5480 5481 pool = &(per_cpu_ptr(pools, cpu)[highpri]); 5482 pwq_p = per_cpu_ptr(wq->cpu_pwq, cpu); 5483 5484 *pwq_p = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, 5485 pool->node); 5486 if (!*pwq_p) 5487 goto enomem; 5488 5489 init_pwq(*pwq_p, wq, pool); 5490 5491 mutex_lock(&wq->mutex); 5492 link_pwq(*pwq_p); 5493 mutex_unlock(&wq->mutex); 5494 } 5495 return 0; 5496 } 5497 5498 if (wq->flags & __WQ_ORDERED) { 5499 struct pool_workqueue *dfl_pwq; 5500 5501 ret = apply_workqueue_attrs_locked(wq, ordered_wq_attrs[highpri]); 5502 /* there should only be single pwq for ordering guarantee */ 5503 dfl_pwq = rcu_access_pointer(wq->dfl_pwq); 5504 WARN(!ret && (wq->pwqs.next != &dfl_pwq->pwqs_node || 5505 wq->pwqs.prev != &dfl_pwq->pwqs_node), 5506 "ordering guarantee broken for workqueue %s\n", wq->name); 5507 } else { 5508 ret = apply_workqueue_attrs_locked(wq, unbound_std_wq_attrs[highpri]); 5509 } 5510 5511 return ret; 5512 5513 enomem: 5514 if (wq->cpu_pwq) { 5515 for_each_possible_cpu(cpu) { 5516 struct pool_workqueue *pwq = *per_cpu_ptr(wq->cpu_pwq, cpu); 5517 5518 if (pwq) 5519 kmem_cache_free(pwq_cache, pwq); 5520 } 5521 free_percpu(wq->cpu_pwq); 5522 wq->cpu_pwq = NULL; 5523 } 5524 return -ENOMEM; 5525 } 5526 5527 static int wq_clamp_max_active(int max_active, unsigned int flags, 5528 const char *name) 5529 { 5530 if (max_active < 1 || max_active > WQ_MAX_ACTIVE) 5531 pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n", 5532 max_active, name, 1, WQ_MAX_ACTIVE); 5533 5534 return clamp_val(max_active, 1, WQ_MAX_ACTIVE); 5535 } 5536 5537 /* 5538 * Workqueues which may be used during memory reclaim should have a rescuer 5539 * to guarantee forward progress. 5540 */ 5541 static int init_rescuer(struct workqueue_struct *wq) 5542 { 5543 struct worker *rescuer; 5544 char id_buf[WORKER_ID_LEN]; 5545 int ret; 5546 5547 lockdep_assert_held(&wq_pool_mutex); 5548 5549 if (!(wq->flags & WQ_MEM_RECLAIM)) 5550 return 0; 5551 5552 rescuer = alloc_worker(NUMA_NO_NODE); 5553 if (!rescuer) { 5554 pr_err("workqueue: Failed to allocate a rescuer for wq \"%s\"\n", 5555 wq->name); 5556 return -ENOMEM; 5557 } 5558 5559 rescuer->rescue_wq = wq; 5560 format_worker_id(id_buf, sizeof(id_buf), rescuer, NULL); 5561 5562 rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", id_buf); 5563 if (IS_ERR(rescuer->task)) { 5564 ret = PTR_ERR(rescuer->task); 5565 pr_err("workqueue: Failed to create a rescuer kthread for wq \"%s\": %pe", 5566 wq->name, ERR_PTR(ret)); 5567 kfree(rescuer); 5568 return ret; 5569 } 5570 5571 wq->rescuer = rescuer; 5572 if (wq->flags & WQ_UNBOUND) 5573 kthread_bind_mask(rescuer->task, unbound_effective_cpumask(wq)); 5574 else 5575 kthread_bind_mask(rescuer->task, cpu_possible_mask); 5576 wake_up_process(rescuer->task); 5577 5578 return 0; 5579 } 5580 5581 /** 5582 * wq_adjust_max_active - update a wq's max_active to the current setting 5583 * @wq: target workqueue 5584 * 5585 * If @wq isn't freezing, set @wq->max_active to the saved_max_active and 5586 * activate inactive work items accordingly. If @wq is freezing, clear 5587 * @wq->max_active to zero. 5588 */ 5589 static void wq_adjust_max_active(struct workqueue_struct *wq) 5590 { 5591 bool activated; 5592 int new_max, new_min; 5593 5594 lockdep_assert_held(&wq->mutex); 5595 5596 if ((wq->flags & WQ_FREEZABLE) && workqueue_freezing) { 5597 new_max = 0; 5598 new_min = 0; 5599 } else { 5600 new_max = wq->saved_max_active; 5601 new_min = wq->saved_min_active; 5602 } 5603 5604 if (wq->max_active == new_max && wq->min_active == new_min) 5605 return; 5606 5607 /* 5608 * Update @wq->max/min_active and then kick inactive work items if more 5609 * active work items are allowed. This doesn't break work item ordering 5610 * because new work items are always queued behind existing inactive 5611 * work items if there are any. 5612 */ 5613 WRITE_ONCE(wq->max_active, new_max); 5614 WRITE_ONCE(wq->min_active, new_min); 5615 5616 if (wq->flags & WQ_UNBOUND) 5617 wq_update_node_max_active(wq, -1); 5618 5619 if (new_max == 0) 5620 return; 5621 5622 /* 5623 * Round-robin through pwq's activating the first inactive work item 5624 * until max_active is filled. 5625 */ 5626 do { 5627 struct pool_workqueue *pwq; 5628 5629 activated = false; 5630 for_each_pwq(pwq, wq) { 5631 unsigned long irq_flags; 5632 5633 /* can be called during early boot w/ irq disabled */ 5634 raw_spin_lock_irqsave(&pwq->pool->lock, irq_flags); 5635 if (pwq_activate_first_inactive(pwq, true)) { 5636 activated = true; 5637 kick_pool(pwq->pool); 5638 } 5639 raw_spin_unlock_irqrestore(&pwq->pool->lock, irq_flags); 5640 } 5641 } while (activated); 5642 } 5643 5644 static struct workqueue_struct *__alloc_workqueue(const char *fmt, 5645 unsigned int flags, 5646 int max_active, va_list args) 5647 { 5648 struct workqueue_struct *wq; 5649 size_t wq_size; 5650 int name_len; 5651 5652 if (flags & WQ_BH) { 5653 if (WARN_ON_ONCE(flags & ~__WQ_BH_ALLOWS)) 5654 return NULL; 5655 if (WARN_ON_ONCE(max_active)) 5656 return NULL; 5657 } 5658 5659 /* see the comment above the definition of WQ_POWER_EFFICIENT */ 5660 if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient) 5661 flags |= WQ_UNBOUND; 5662 5663 /* allocate wq and format name */ 5664 if (flags & WQ_UNBOUND) 5665 wq_size = struct_size(wq, node_nr_active, nr_node_ids + 1); 5666 else 5667 wq_size = sizeof(*wq); 5668 5669 wq = kzalloc(wq_size, GFP_KERNEL); 5670 if (!wq) 5671 return NULL; 5672 5673 if (flags & WQ_UNBOUND) { 5674 wq->unbound_attrs = alloc_workqueue_attrs(); 5675 if (!wq->unbound_attrs) 5676 goto err_free_wq; 5677 } 5678 5679 name_len = vsnprintf(wq->name, sizeof(wq->name), fmt, args); 5680 5681 if (name_len >= WQ_NAME_LEN) 5682 pr_warn_once("workqueue: name exceeds WQ_NAME_LEN. Truncating to: %s\n", 5683 wq->name); 5684 5685 if (flags & WQ_BH) { 5686 /* 5687 * BH workqueues always share a single execution context per CPU 5688 * and don't impose any max_active limit. 5689 */ 5690 max_active = INT_MAX; 5691 } else { 5692 max_active = max_active ?: WQ_DFL_ACTIVE; 5693 max_active = wq_clamp_max_active(max_active, flags, wq->name); 5694 } 5695 5696 /* init wq */ 5697 wq->flags = flags; 5698 wq->max_active = max_active; 5699 wq->min_active = min(max_active, WQ_DFL_MIN_ACTIVE); 5700 wq->saved_max_active = wq->max_active; 5701 wq->saved_min_active = wq->min_active; 5702 mutex_init(&wq->mutex); 5703 atomic_set(&wq->nr_pwqs_to_flush, 0); 5704 INIT_LIST_HEAD(&wq->pwqs); 5705 INIT_LIST_HEAD(&wq->flusher_queue); 5706 INIT_LIST_HEAD(&wq->flusher_overflow); 5707 INIT_LIST_HEAD(&wq->maydays); 5708 5709 INIT_LIST_HEAD(&wq->list); 5710 5711 if (flags & WQ_UNBOUND) { 5712 if (alloc_node_nr_active(wq->node_nr_active) < 0) 5713 goto err_free_wq; 5714 } 5715 5716 /* 5717 * wq_pool_mutex protects the workqueues list, allocations of PWQs, 5718 * and the global freeze state. 5719 */ 5720 apply_wqattrs_lock(); 5721 5722 if (alloc_and_link_pwqs(wq) < 0) 5723 goto err_unlock_free_node_nr_active; 5724 5725 mutex_lock(&wq->mutex); 5726 wq_adjust_max_active(wq); 5727 mutex_unlock(&wq->mutex); 5728 5729 list_add_tail_rcu(&wq->list, &workqueues); 5730 5731 if (wq_online && init_rescuer(wq) < 0) 5732 goto err_unlock_destroy; 5733 5734 apply_wqattrs_unlock(); 5735 5736 if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq)) 5737 goto err_destroy; 5738 5739 return wq; 5740 5741 err_unlock_free_node_nr_active: 5742 apply_wqattrs_unlock(); 5743 /* 5744 * Failed alloc_and_link_pwqs() may leave pending pwq->release_work, 5745 * flushing the pwq_release_worker ensures that the pwq_release_workfn() 5746 * completes before calling kfree(wq). 5747 */ 5748 if (wq->flags & WQ_UNBOUND) { 5749 kthread_flush_worker(pwq_release_worker); 5750 free_node_nr_active(wq->node_nr_active); 5751 } 5752 err_free_wq: 5753 free_workqueue_attrs(wq->unbound_attrs); 5754 kfree(wq); 5755 return NULL; 5756 err_unlock_destroy: 5757 apply_wqattrs_unlock(); 5758 err_destroy: 5759 destroy_workqueue(wq); 5760 return NULL; 5761 } 5762 5763 __printf(1, 4) 5764 struct workqueue_struct *alloc_workqueue(const char *fmt, 5765 unsigned int flags, 5766 int max_active, ...) 5767 { 5768 struct workqueue_struct *wq; 5769 va_list args; 5770 5771 va_start(args, max_active); 5772 wq = __alloc_workqueue(fmt, flags, max_active, args); 5773 va_end(args); 5774 if (!wq) 5775 return NULL; 5776 5777 wq_init_lockdep(wq); 5778 5779 return wq; 5780 } 5781 EXPORT_SYMBOL_GPL(alloc_workqueue); 5782 5783 #ifdef CONFIG_LOCKDEP 5784 __printf(1, 5) 5785 struct workqueue_struct * 5786 alloc_workqueue_lockdep_map(const char *fmt, unsigned int flags, 5787 int max_active, struct lockdep_map *lockdep_map, ...) 5788 { 5789 struct workqueue_struct *wq; 5790 va_list args; 5791 5792 va_start(args, lockdep_map); 5793 wq = __alloc_workqueue(fmt, flags, max_active, args); 5794 va_end(args); 5795 if (!wq) 5796 return NULL; 5797 5798 wq->lockdep_map = lockdep_map; 5799 5800 return wq; 5801 } 5802 EXPORT_SYMBOL_GPL(alloc_workqueue_lockdep_map); 5803 #endif 5804 5805 static bool pwq_busy(struct pool_workqueue *pwq) 5806 { 5807 int i; 5808 5809 for (i = 0; i < WORK_NR_COLORS; i++) 5810 if (pwq->nr_in_flight[i]) 5811 return true; 5812 5813 if ((pwq != rcu_access_pointer(pwq->wq->dfl_pwq)) && (pwq->refcnt > 1)) 5814 return true; 5815 if (!pwq_is_empty(pwq)) 5816 return true; 5817 5818 return false; 5819 } 5820 5821 /** 5822 * destroy_workqueue - safely terminate a workqueue 5823 * @wq: target workqueue 5824 * 5825 * Safely destroy a workqueue. All work currently pending will be done first. 5826 */ 5827 void destroy_workqueue(struct workqueue_struct *wq) 5828 { 5829 struct pool_workqueue *pwq; 5830 int cpu; 5831 5832 /* 5833 * Remove it from sysfs first so that sanity check failure doesn't 5834 * lead to sysfs name conflicts. 5835 */ 5836 workqueue_sysfs_unregister(wq); 5837 5838 /* mark the workqueue destruction is in progress */ 5839 mutex_lock(&wq->mutex); 5840 wq->flags |= __WQ_DESTROYING; 5841 mutex_unlock(&wq->mutex); 5842 5843 /* drain it before proceeding with destruction */ 5844 drain_workqueue(wq); 5845 5846 /* kill rescuer, if sanity checks fail, leave it w/o rescuer */ 5847 if (wq->rescuer) { 5848 struct worker *rescuer = wq->rescuer; 5849 5850 /* this prevents new queueing */ 5851 raw_spin_lock_irq(&wq_mayday_lock); 5852 wq->rescuer = NULL; 5853 raw_spin_unlock_irq(&wq_mayday_lock); 5854 5855 /* rescuer will empty maydays list before exiting */ 5856 kthread_stop(rescuer->task); 5857 kfree(rescuer); 5858 } 5859 5860 /* 5861 * Sanity checks - grab all the locks so that we wait for all 5862 * in-flight operations which may do put_pwq(). 5863 */ 5864 mutex_lock(&wq_pool_mutex); 5865 mutex_lock(&wq->mutex); 5866 for_each_pwq(pwq, wq) { 5867 raw_spin_lock_irq(&pwq->pool->lock); 5868 if (WARN_ON(pwq_busy(pwq))) { 5869 pr_warn("%s: %s has the following busy pwq\n", 5870 __func__, wq->name); 5871 show_pwq(pwq); 5872 raw_spin_unlock_irq(&pwq->pool->lock); 5873 mutex_unlock(&wq->mutex); 5874 mutex_unlock(&wq_pool_mutex); 5875 show_one_workqueue(wq); 5876 return; 5877 } 5878 raw_spin_unlock_irq(&pwq->pool->lock); 5879 } 5880 mutex_unlock(&wq->mutex); 5881 5882 /* 5883 * wq list is used to freeze wq, remove from list after 5884 * flushing is complete in case freeze races us. 5885 */ 5886 list_del_rcu(&wq->list); 5887 mutex_unlock(&wq_pool_mutex); 5888 5889 /* 5890 * We're the sole accessor of @wq. Directly access cpu_pwq and dfl_pwq 5891 * to put the base refs. @wq will be auto-destroyed from the last 5892 * pwq_put. RCU read lock prevents @wq from going away from under us. 5893 */ 5894 rcu_read_lock(); 5895 5896 for_each_possible_cpu(cpu) { 5897 put_pwq_unlocked(unbound_pwq(wq, cpu)); 5898 RCU_INIT_POINTER(*unbound_pwq_slot(wq, cpu), NULL); 5899 } 5900 5901 put_pwq_unlocked(unbound_pwq(wq, -1)); 5902 RCU_INIT_POINTER(*unbound_pwq_slot(wq, -1), NULL); 5903 5904 rcu_read_unlock(); 5905 } 5906 EXPORT_SYMBOL_GPL(destroy_workqueue); 5907 5908 /** 5909 * workqueue_set_max_active - adjust max_active of a workqueue 5910 * @wq: target workqueue 5911 * @max_active: new max_active value. 5912 * 5913 * Set max_active of @wq to @max_active. See the alloc_workqueue() function 5914 * comment. 5915 * 5916 * CONTEXT: 5917 * Don't call from IRQ context. 5918 */ 5919 void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) 5920 { 5921 /* max_active doesn't mean anything for BH workqueues */ 5922 if (WARN_ON(wq->flags & WQ_BH)) 5923 return; 5924 /* disallow meddling with max_active for ordered workqueues */ 5925 if (WARN_ON(wq->flags & __WQ_ORDERED)) 5926 return; 5927 5928 max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); 5929 5930 mutex_lock(&wq->mutex); 5931 5932 wq->saved_max_active = max_active; 5933 if (wq->flags & WQ_UNBOUND) 5934 wq->saved_min_active = min(wq->saved_min_active, max_active); 5935 5936 wq_adjust_max_active(wq); 5937 5938 mutex_unlock(&wq->mutex); 5939 } 5940 EXPORT_SYMBOL_GPL(workqueue_set_max_active); 5941 5942 /** 5943 * workqueue_set_min_active - adjust min_active of an unbound workqueue 5944 * @wq: target unbound workqueue 5945 * @min_active: new min_active value 5946 * 5947 * Set min_active of an unbound workqueue. Unlike other types of workqueues, an 5948 * unbound workqueue is not guaranteed to be able to process max_active 5949 * interdependent work items. Instead, an unbound workqueue is guaranteed to be 5950 * able to process min_active number of interdependent work items which is 5951 * %WQ_DFL_MIN_ACTIVE by default. 5952 * 5953 * Use this function to adjust the min_active value between 0 and the current 5954 * max_active. 5955 */ 5956 void workqueue_set_min_active(struct workqueue_struct *wq, int min_active) 5957 { 5958 /* min_active is only meaningful for non-ordered unbound workqueues */ 5959 if (WARN_ON((wq->flags & (WQ_BH | WQ_UNBOUND | __WQ_ORDERED)) != 5960 WQ_UNBOUND)) 5961 return; 5962 5963 mutex_lock(&wq->mutex); 5964 wq->saved_min_active = clamp(min_active, 0, wq->saved_max_active); 5965 wq_adjust_max_active(wq); 5966 mutex_unlock(&wq->mutex); 5967 } 5968 5969 /** 5970 * current_work - retrieve %current task's work struct 5971 * 5972 * Determine if %current task is a workqueue worker and what it's working on. 5973 * Useful to find out the context that the %current task is running in. 5974 * 5975 * Return: work struct if %current task is a workqueue worker, %NULL otherwise. 5976 */ 5977 struct work_struct *current_work(void) 5978 { 5979 struct worker *worker = current_wq_worker(); 5980 5981 return worker ? worker->current_work : NULL; 5982 } 5983 EXPORT_SYMBOL(current_work); 5984 5985 /** 5986 * current_is_workqueue_rescuer - is %current workqueue rescuer? 5987 * 5988 * Determine whether %current is a workqueue rescuer. Can be used from 5989 * work functions to determine whether it's being run off the rescuer task. 5990 * 5991 * Return: %true if %current is a workqueue rescuer. %false otherwise. 5992 */ 5993 bool current_is_workqueue_rescuer(void) 5994 { 5995 struct worker *worker = current_wq_worker(); 5996 5997 return worker && worker->rescue_wq; 5998 } 5999 6000 /** 6001 * workqueue_congested - test whether a workqueue is congested 6002 * @cpu: CPU in question 6003 * @wq: target workqueue 6004 * 6005 * Test whether @wq's cpu workqueue for @cpu is congested. There is 6006 * no synchronization around this function and the test result is 6007 * unreliable and only useful as advisory hints or for debugging. 6008 * 6009 * If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU. 6010 * 6011 * With the exception of ordered workqueues, all workqueues have per-cpu 6012 * pool_workqueues, each with its own congested state. A workqueue being 6013 * congested on one CPU doesn't mean that the workqueue is contested on any 6014 * other CPUs. 6015 * 6016 * Return: 6017 * %true if congested, %false otherwise. 6018 */ 6019 bool workqueue_congested(int cpu, struct workqueue_struct *wq) 6020 { 6021 struct pool_workqueue *pwq; 6022 bool ret; 6023 6024 rcu_read_lock(); 6025 preempt_disable(); 6026 6027 if (cpu == WORK_CPU_UNBOUND) 6028 cpu = smp_processor_id(); 6029 6030 pwq = *per_cpu_ptr(wq->cpu_pwq, cpu); 6031 ret = !list_empty(&pwq->inactive_works); 6032 6033 preempt_enable(); 6034 rcu_read_unlock(); 6035 6036 return ret; 6037 } 6038 EXPORT_SYMBOL_GPL(workqueue_congested); 6039 6040 /** 6041 * work_busy - test whether a work is currently pending or running 6042 * @work: the work to be tested 6043 * 6044 * Test whether @work is currently pending or running. There is no 6045 * synchronization around this function and the test result is 6046 * unreliable and only useful as advisory hints or for debugging. 6047 * 6048 * Return: 6049 * OR'd bitmask of WORK_BUSY_* bits. 6050 */ 6051 unsigned int work_busy(struct work_struct *work) 6052 { 6053 struct worker_pool *pool; 6054 unsigned long irq_flags; 6055 unsigned int ret = 0; 6056 6057 if (work_pending(work)) 6058 ret |= WORK_BUSY_PENDING; 6059 6060 rcu_read_lock(); 6061 pool = get_work_pool(work); 6062 if (pool) { 6063 raw_spin_lock_irqsave(&pool->lock, irq_flags); 6064 if (find_worker_executing_work(pool, work)) 6065 ret |= WORK_BUSY_RUNNING; 6066 raw_spin_unlock_irqrestore(&pool->lock, irq_flags); 6067 } 6068 rcu_read_unlock(); 6069 6070 return ret; 6071 } 6072 EXPORT_SYMBOL_GPL(work_busy); 6073 6074 /** 6075 * set_worker_desc - set description for the current work item 6076 * @fmt: printf-style format string 6077 * @...: arguments for the format string 6078 * 6079 * This function can be called by a running work function to describe what 6080 * the work item is about. If the worker task gets dumped, this 6081 * information will be printed out together to help debugging. The 6082 * description can be at most WORKER_DESC_LEN including the trailing '\0'. 6083 */ 6084 void set_worker_desc(const char *fmt, ...) 6085 { 6086 struct worker *worker = current_wq_worker(); 6087 va_list args; 6088 6089 if (worker) { 6090 va_start(args, fmt); 6091 vsnprintf(worker->desc, sizeof(worker->desc), fmt, args); 6092 va_end(args); 6093 } 6094 } 6095 EXPORT_SYMBOL_GPL(set_worker_desc); 6096 6097 /** 6098 * print_worker_info - print out worker information and description 6099 * @log_lvl: the log level to use when printing 6100 * @task: target task 6101 * 6102 * If @task is a worker and currently executing a work item, print out the 6103 * name of the workqueue being serviced and worker description set with 6104 * set_worker_desc() by the currently executing work item. 6105 * 6106 * This function can be safely called on any task as long as the 6107 * task_struct itself is accessible. While safe, this function isn't 6108 * synchronized and may print out mixups or garbages of limited length. 6109 */ 6110 void print_worker_info(const char *log_lvl, struct task_struct *task) 6111 { 6112 work_func_t *fn = NULL; 6113 char name[WQ_NAME_LEN] = { }; 6114 char desc[WORKER_DESC_LEN] = { }; 6115 struct pool_workqueue *pwq = NULL; 6116 struct workqueue_struct *wq = NULL; 6117 struct worker *worker; 6118 6119 if (!(task->flags & PF_WQ_WORKER)) 6120 return; 6121 6122 /* 6123 * This function is called without any synchronization and @task 6124 * could be in any state. Be careful with dereferences. 6125 */ 6126 worker = kthread_probe_data(task); 6127 6128 /* 6129 * Carefully copy the associated workqueue's workfn, name and desc. 6130 * Keep the original last '\0' in case the original is garbage. 6131 */ 6132 copy_from_kernel_nofault(&fn, &worker->current_func, sizeof(fn)); 6133 copy_from_kernel_nofault(&pwq, &worker->current_pwq, sizeof(pwq)); 6134 copy_from_kernel_nofault(&wq, &pwq->wq, sizeof(wq)); 6135 copy_from_kernel_nofault(name, wq->name, sizeof(name) - 1); 6136 copy_from_kernel_nofault(desc, worker->desc, sizeof(desc) - 1); 6137 6138 if (fn || name[0] || desc[0]) { 6139 printk("%sWorkqueue: %s %ps", log_lvl, name, fn); 6140 if (strcmp(name, desc)) 6141 pr_cont(" (%s)", desc); 6142 pr_cont("\n"); 6143 } 6144 } 6145 6146 static void pr_cont_pool_info(struct worker_pool *pool) 6147 { 6148 pr_cont(" cpus=%*pbl", nr_cpumask_bits, pool->attrs->cpumask); 6149 if (pool->node != NUMA_NO_NODE) 6150 pr_cont(" node=%d", pool->node); 6151 pr_cont(" flags=0x%x", pool->flags); 6152 if (pool->flags & POOL_BH) 6153 pr_cont(" bh%s", 6154 pool->attrs->nice == HIGHPRI_NICE_LEVEL ? "-hi" : ""); 6155 else 6156 pr_cont(" nice=%d", pool->attrs->nice); 6157 } 6158 6159 static void pr_cont_worker_id(struct worker *worker) 6160 { 6161 struct worker_pool *pool = worker->pool; 6162 6163 if (pool->flags & WQ_BH) 6164 pr_cont("bh%s", 6165 pool->attrs->nice == HIGHPRI_NICE_LEVEL ? "-hi" : ""); 6166 else 6167 pr_cont("%d%s", task_pid_nr(worker->task), 6168 worker->rescue_wq ? "(RESCUER)" : ""); 6169 } 6170 6171 struct pr_cont_work_struct { 6172 bool comma; 6173 work_func_t func; 6174 long ctr; 6175 }; 6176 6177 static void pr_cont_work_flush(bool comma, work_func_t func, struct pr_cont_work_struct *pcwsp) 6178 { 6179 if (!pcwsp->ctr) 6180 goto out_record; 6181 if (func == pcwsp->func) { 6182 pcwsp->ctr++; 6183 return; 6184 } 6185 if (pcwsp->ctr == 1) 6186 pr_cont("%s %ps", pcwsp->comma ? "," : "", pcwsp->func); 6187 else 6188 pr_cont("%s %ld*%ps", pcwsp->comma ? "," : "", pcwsp->ctr, pcwsp->func); 6189 pcwsp->ctr = 0; 6190 out_record: 6191 if ((long)func == -1L) 6192 return; 6193 pcwsp->comma = comma; 6194 pcwsp->func = func; 6195 pcwsp->ctr = 1; 6196 } 6197 6198 static void pr_cont_work(bool comma, struct work_struct *work, struct pr_cont_work_struct *pcwsp) 6199 { 6200 if (work->func == wq_barrier_func) { 6201 struct wq_barrier *barr; 6202 6203 barr = container_of(work, struct wq_barrier, work); 6204 6205 pr_cont_work_flush(comma, (work_func_t)-1, pcwsp); 6206 pr_cont("%s BAR(%d)", comma ? "," : "", 6207 task_pid_nr(barr->task)); 6208 } else { 6209 if (!comma) 6210 pr_cont_work_flush(comma, (work_func_t)-1, pcwsp); 6211 pr_cont_work_flush(comma, work->func, pcwsp); 6212 } 6213 } 6214 6215 static void show_pwq(struct pool_workqueue *pwq) 6216 { 6217 struct pr_cont_work_struct pcws = { .ctr = 0, }; 6218 struct worker_pool *pool = pwq->pool; 6219 struct work_struct *work; 6220 struct worker *worker; 6221 bool has_in_flight = false, has_pending = false; 6222 int bkt; 6223 6224 pr_info(" pwq %d:", pool->id); 6225 pr_cont_pool_info(pool); 6226 6227 pr_cont(" active=%d refcnt=%d%s\n", 6228 pwq->nr_active, pwq->refcnt, 6229 !list_empty(&pwq->mayday_node) ? " MAYDAY" : ""); 6230 6231 hash_for_each(pool->busy_hash, bkt, worker, hentry) { 6232 if (worker->current_pwq == pwq) { 6233 has_in_flight = true; 6234 break; 6235 } 6236 } 6237 if (has_in_flight) { 6238 bool comma = false; 6239 6240 pr_info(" in-flight:"); 6241 hash_for_each(pool->busy_hash, bkt, worker, hentry) { 6242 if (worker->current_pwq != pwq) 6243 continue; 6244 6245 pr_cont(" %s", comma ? "," : ""); 6246 pr_cont_worker_id(worker); 6247 pr_cont(":%ps", worker->current_func); 6248 list_for_each_entry(work, &worker->scheduled, entry) 6249 pr_cont_work(false, work, &pcws); 6250 pr_cont_work_flush(comma, (work_func_t)-1L, &pcws); 6251 comma = true; 6252 } 6253 pr_cont("\n"); 6254 } 6255 6256 list_for_each_entry(work, &pool->worklist, entry) { 6257 if (get_work_pwq(work) == pwq) { 6258 has_pending = true; 6259 break; 6260 } 6261 } 6262 if (has_pending) { 6263 bool comma = false; 6264 6265 pr_info(" pending:"); 6266 list_for_each_entry(work, &pool->worklist, entry) { 6267 if (get_work_pwq(work) != pwq) 6268 continue; 6269 6270 pr_cont_work(comma, work, &pcws); 6271 comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); 6272 } 6273 pr_cont_work_flush(comma, (work_func_t)-1L, &pcws); 6274 pr_cont("\n"); 6275 } 6276 6277 if (!list_empty(&pwq->inactive_works)) { 6278 bool comma = false; 6279 6280 pr_info(" inactive:"); 6281 list_for_each_entry(work, &pwq->inactive_works, entry) { 6282 pr_cont_work(comma, work, &pcws); 6283 comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); 6284 } 6285 pr_cont_work_flush(comma, (work_func_t)-1L, &pcws); 6286 pr_cont("\n"); 6287 } 6288 } 6289 6290 /** 6291 * show_one_workqueue - dump state of specified workqueue 6292 * @wq: workqueue whose state will be printed 6293 */ 6294 void show_one_workqueue(struct workqueue_struct *wq) 6295 { 6296 struct pool_workqueue *pwq; 6297 bool idle = true; 6298 unsigned long irq_flags; 6299 6300 for_each_pwq(pwq, wq) { 6301 if (!pwq_is_empty(pwq)) { 6302 idle = false; 6303 break; 6304 } 6305 } 6306 if (idle) /* Nothing to print for idle workqueue */ 6307 return; 6308 6309 pr_info("workqueue %s: flags=0x%x\n", wq->name, wq->flags); 6310 6311 for_each_pwq(pwq, wq) { 6312 raw_spin_lock_irqsave(&pwq->pool->lock, irq_flags); 6313 if (!pwq_is_empty(pwq)) { 6314 /* 6315 * Defer printing to avoid deadlocks in console 6316 * drivers that queue work while holding locks 6317 * also taken in their write paths. 6318 */ 6319 printk_deferred_enter(); 6320 show_pwq(pwq); 6321 printk_deferred_exit(); 6322 } 6323 raw_spin_unlock_irqrestore(&pwq->pool->lock, irq_flags); 6324 /* 6325 * We could be printing a lot from atomic context, e.g. 6326 * sysrq-t -> show_all_workqueues(). Avoid triggering 6327 * hard lockup. 6328 */ 6329 touch_nmi_watchdog(); 6330 } 6331 6332 } 6333 6334 /** 6335 * show_one_worker_pool - dump state of specified worker pool 6336 * @pool: worker pool whose state will be printed 6337 */ 6338 static void show_one_worker_pool(struct worker_pool *pool) 6339 { 6340 struct worker *worker; 6341 bool first = true; 6342 unsigned long irq_flags; 6343 unsigned long hung = 0; 6344 6345 raw_spin_lock_irqsave(&pool->lock, irq_flags); 6346 if (pool->nr_workers == pool->nr_idle) 6347 goto next_pool; 6348 6349 /* How long the first pending work is waiting for a worker. */ 6350 if (!list_empty(&pool->worklist)) 6351 hung = jiffies_to_msecs(jiffies - pool->watchdog_ts) / 1000; 6352 6353 /* 6354 * Defer printing to avoid deadlocks in console drivers that 6355 * queue work while holding locks also taken in their write 6356 * paths. 6357 */ 6358 printk_deferred_enter(); 6359 pr_info("pool %d:", pool->id); 6360 pr_cont_pool_info(pool); 6361 pr_cont(" hung=%lus workers=%d", hung, pool->nr_workers); 6362 if (pool->manager) 6363 pr_cont(" manager: %d", 6364 task_pid_nr(pool->manager->task)); 6365 list_for_each_entry(worker, &pool->idle_list, entry) { 6366 pr_cont(" %s", first ? "idle: " : ""); 6367 pr_cont_worker_id(worker); 6368 first = false; 6369 } 6370 pr_cont("\n"); 6371 printk_deferred_exit(); 6372 next_pool: 6373 raw_spin_unlock_irqrestore(&pool->lock, irq_flags); 6374 /* 6375 * We could be printing a lot from atomic context, e.g. 6376 * sysrq-t -> show_all_workqueues(). Avoid triggering 6377 * hard lockup. 6378 */ 6379 touch_nmi_watchdog(); 6380 6381 } 6382 6383 /** 6384 * show_all_workqueues - dump workqueue state 6385 * 6386 * Called from a sysrq handler and prints out all busy workqueues and pools. 6387 */ 6388 void show_all_workqueues(void) 6389 { 6390 struct workqueue_struct *wq; 6391 struct worker_pool *pool; 6392 int pi; 6393 6394 rcu_read_lock(); 6395 6396 pr_info("Showing busy workqueues and worker pools:\n"); 6397 6398 list_for_each_entry_rcu(wq, &workqueues, list) 6399 show_one_workqueue(wq); 6400 6401 for_each_pool(pool, pi) 6402 show_one_worker_pool(pool); 6403 6404 rcu_read_unlock(); 6405 } 6406 6407 /** 6408 * show_freezable_workqueues - dump freezable workqueue state 6409 * 6410 * Called from try_to_freeze_tasks() and prints out all freezable workqueues 6411 * still busy. 6412 */ 6413 void show_freezable_workqueues(void) 6414 { 6415 struct workqueue_struct *wq; 6416 6417 rcu_read_lock(); 6418 6419 pr_info("Showing freezable workqueues that are still busy:\n"); 6420 6421 list_for_each_entry_rcu(wq, &workqueues, list) { 6422 if (!(wq->flags & WQ_FREEZABLE)) 6423 continue; 6424 show_one_workqueue(wq); 6425 } 6426 6427 rcu_read_unlock(); 6428 } 6429 6430 /* used to show worker information through /proc/PID/{comm,stat,status} */ 6431 void wq_worker_comm(char *buf, size_t size, struct task_struct *task) 6432 { 6433 /* stabilize PF_WQ_WORKER and worker pool association */ 6434 mutex_lock(&wq_pool_attach_mutex); 6435 6436 if (task->flags & PF_WQ_WORKER) { 6437 struct worker *worker = kthread_data(task); 6438 struct worker_pool *pool = worker->pool; 6439 int off; 6440 6441 off = format_worker_id(buf, size, worker, pool); 6442 6443 if (pool) { 6444 raw_spin_lock_irq(&pool->lock); 6445 /* 6446 * ->desc tracks information (wq name or 6447 * set_worker_desc()) for the latest execution. If 6448 * current, prepend '+', otherwise '-'. 6449 */ 6450 if (worker->desc[0] != '\0') { 6451 if (worker->current_work) 6452 scnprintf(buf + off, size - off, "+%s", 6453 worker->desc); 6454 else 6455 scnprintf(buf + off, size - off, "-%s", 6456 worker->desc); 6457 } 6458 raw_spin_unlock_irq(&pool->lock); 6459 } 6460 } else { 6461 strscpy(buf, task->comm, size); 6462 } 6463 6464 mutex_unlock(&wq_pool_attach_mutex); 6465 } 6466 6467 #ifdef CONFIG_SMP 6468 6469 /* 6470 * CPU hotplug. 6471 * 6472 * There are two challenges in supporting CPU hotplug. Firstly, there 6473 * are a lot of assumptions on strong associations among work, pwq and 6474 * pool which make migrating pending and scheduled works very 6475 * difficult to implement without impacting hot paths. Secondly, 6476 * worker pools serve mix of short, long and very long running works making 6477 * blocked draining impractical. 6478 * 6479 * This is solved by allowing the pools to be disassociated from the CPU 6480 * running as an unbound one and allowing it to be reattached later if the 6481 * cpu comes back online. 6482 */ 6483 6484 static void unbind_workers(int cpu) 6485 { 6486 struct worker_pool *pool; 6487 struct worker *worker; 6488 6489 for_each_cpu_worker_pool(pool, cpu) { 6490 mutex_lock(&wq_pool_attach_mutex); 6491 raw_spin_lock_irq(&pool->lock); 6492 6493 /* 6494 * We've blocked all attach/detach operations. Make all workers 6495 * unbound and set DISASSOCIATED. Before this, all workers 6496 * must be on the cpu. After this, they may become diasporas. 6497 * And the preemption disabled section in their sched callbacks 6498 * are guaranteed to see WORKER_UNBOUND since the code here 6499 * is on the same cpu. 6500 */ 6501 for_each_pool_worker(worker, pool) 6502 worker->flags |= WORKER_UNBOUND; 6503 6504 pool->flags |= POOL_DISASSOCIATED; 6505 6506 /* 6507 * The handling of nr_running in sched callbacks are disabled 6508 * now. Zap nr_running. After this, nr_running stays zero and 6509 * need_more_worker() and keep_working() are always true as 6510 * long as the worklist is not empty. This pool now behaves as 6511 * an unbound (in terms of concurrency management) pool which 6512 * are served by workers tied to the pool. 6513 */ 6514 pool->nr_running = 0; 6515 6516 /* 6517 * With concurrency management just turned off, a busy 6518 * worker blocking could lead to lengthy stalls. Kick off 6519 * unbound chain execution of currently pending work items. 6520 */ 6521 kick_pool(pool); 6522 6523 raw_spin_unlock_irq(&pool->lock); 6524 6525 for_each_pool_worker(worker, pool) 6526 unbind_worker(worker); 6527 6528 mutex_unlock(&wq_pool_attach_mutex); 6529 } 6530 } 6531 6532 /** 6533 * rebind_workers - rebind all workers of a pool to the associated CPU 6534 * @pool: pool of interest 6535 * 6536 * @pool->cpu is coming online. Rebind all workers to the CPU. 6537 */ 6538 static void rebind_workers(struct worker_pool *pool) 6539 { 6540 struct worker *worker; 6541 6542 lockdep_assert_held(&wq_pool_attach_mutex); 6543 6544 /* 6545 * Restore CPU affinity of all workers. As all idle workers should 6546 * be on the run-queue of the associated CPU before any local 6547 * wake-ups for concurrency management happen, restore CPU affinity 6548 * of all workers first and then clear UNBOUND. As we're called 6549 * from CPU_ONLINE, the following shouldn't fail. 6550 */ 6551 for_each_pool_worker(worker, pool) { 6552 kthread_set_per_cpu(worker->task, pool->cpu); 6553 WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, 6554 pool_allowed_cpus(pool)) < 0); 6555 } 6556 6557 raw_spin_lock_irq(&pool->lock); 6558 6559 pool->flags &= ~POOL_DISASSOCIATED; 6560 6561 for_each_pool_worker(worker, pool) { 6562 unsigned int worker_flags = worker->flags; 6563 6564 /* 6565 * We want to clear UNBOUND but can't directly call 6566 * worker_clr_flags() or adjust nr_running. Atomically 6567 * replace UNBOUND with another NOT_RUNNING flag REBOUND. 6568 * @worker will clear REBOUND using worker_clr_flags() when 6569 * it initiates the next execution cycle thus restoring 6570 * concurrency management. Note that when or whether 6571 * @worker clears REBOUND doesn't affect correctness. 6572 * 6573 * WRITE_ONCE() is necessary because @worker->flags may be 6574 * tested without holding any lock in 6575 * wq_worker_running(). Without it, NOT_RUNNING test may 6576 * fail incorrectly leading to premature concurrency 6577 * management operations. 6578 */ 6579 WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND)); 6580 worker_flags |= WORKER_REBOUND; 6581 worker_flags &= ~WORKER_UNBOUND; 6582 WRITE_ONCE(worker->flags, worker_flags); 6583 } 6584 6585 raw_spin_unlock_irq(&pool->lock); 6586 } 6587 6588 /** 6589 * restore_unbound_workers_cpumask - restore cpumask of unbound workers 6590 * @pool: unbound pool of interest 6591 * @cpu: the CPU which is coming up 6592 * 6593 * An unbound pool may end up with a cpumask which doesn't have any online 6594 * CPUs. When a worker of such pool get scheduled, the scheduler resets 6595 * its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any 6596 * online CPU before, cpus_allowed of all its workers should be restored. 6597 */ 6598 static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu) 6599 { 6600 static cpumask_t cpumask; 6601 struct worker *worker; 6602 6603 lockdep_assert_held(&wq_pool_attach_mutex); 6604 6605 /* is @cpu allowed for @pool? */ 6606 if (!cpumask_test_cpu(cpu, pool->attrs->cpumask)) 6607 return; 6608 6609 cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask); 6610 6611 /* as we're called from CPU_ONLINE, the following shouldn't fail */ 6612 for_each_pool_worker(worker, pool) 6613 WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, &cpumask) < 0); 6614 } 6615 6616 int workqueue_prepare_cpu(unsigned int cpu) 6617 { 6618 struct worker_pool *pool; 6619 6620 for_each_cpu_worker_pool(pool, cpu) { 6621 if (pool->nr_workers) 6622 continue; 6623 if (!create_worker(pool)) 6624 return -ENOMEM; 6625 } 6626 return 0; 6627 } 6628 6629 int workqueue_online_cpu(unsigned int cpu) 6630 { 6631 struct worker_pool *pool; 6632 struct workqueue_struct *wq; 6633 int pi; 6634 6635 mutex_lock(&wq_pool_mutex); 6636 6637 cpumask_set_cpu(cpu, wq_online_cpumask); 6638 6639 for_each_pool(pool, pi) { 6640 /* BH pools aren't affected by hotplug */ 6641 if (pool->flags & POOL_BH) 6642 continue; 6643 6644 mutex_lock(&wq_pool_attach_mutex); 6645 if (pool->cpu == cpu) 6646 rebind_workers(pool); 6647 else if (pool->cpu < 0) 6648 restore_unbound_workers_cpumask(pool, cpu); 6649 mutex_unlock(&wq_pool_attach_mutex); 6650 } 6651 6652 /* update pod affinity of unbound workqueues */ 6653 list_for_each_entry(wq, &workqueues, list) { 6654 struct workqueue_attrs *attrs = wq->unbound_attrs; 6655 6656 if (attrs) { 6657 const struct wq_pod_type *pt = wqattrs_pod_type(attrs); 6658 int tcpu; 6659 6660 for_each_cpu(tcpu, pt->pod_cpus[pt->cpu_pod[cpu]]) 6661 unbound_wq_update_pwq(wq, tcpu); 6662 6663 mutex_lock(&wq->mutex); 6664 wq_update_node_max_active(wq, -1); 6665 mutex_unlock(&wq->mutex); 6666 } 6667 } 6668 6669 mutex_unlock(&wq_pool_mutex); 6670 return 0; 6671 } 6672 6673 int workqueue_offline_cpu(unsigned int cpu) 6674 { 6675 struct workqueue_struct *wq; 6676 6677 /* unbinding per-cpu workers should happen on the local CPU */ 6678 if (WARN_ON(cpu != smp_processor_id())) 6679 return -1; 6680 6681 unbind_workers(cpu); 6682 6683 /* update pod affinity of unbound workqueues */ 6684 mutex_lock(&wq_pool_mutex); 6685 6686 cpumask_clear_cpu(cpu, wq_online_cpumask); 6687 6688 list_for_each_entry(wq, &workqueues, list) { 6689 struct workqueue_attrs *attrs = wq->unbound_attrs; 6690 6691 if (attrs) { 6692 const struct wq_pod_type *pt = wqattrs_pod_type(attrs); 6693 int tcpu; 6694 6695 for_each_cpu(tcpu, pt->pod_cpus[pt->cpu_pod[cpu]]) 6696 unbound_wq_update_pwq(wq, tcpu); 6697 6698 mutex_lock(&wq->mutex); 6699 wq_update_node_max_active(wq, cpu); 6700 mutex_unlock(&wq->mutex); 6701 } 6702 } 6703 mutex_unlock(&wq_pool_mutex); 6704 6705 return 0; 6706 } 6707 6708 struct work_for_cpu { 6709 struct work_struct work; 6710 long (*fn)(void *); 6711 void *arg; 6712 long ret; 6713 }; 6714 6715 static void work_for_cpu_fn(struct work_struct *work) 6716 { 6717 struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work); 6718 6719 wfc->ret = wfc->fn(wfc->arg); 6720 } 6721 6722 /** 6723 * work_on_cpu_key - run a function in thread context on a particular cpu 6724 * @cpu: the cpu to run on 6725 * @fn: the function to run 6726 * @arg: the function arg 6727 * @key: The lock class key for lock debugging purposes 6728 * 6729 * It is up to the caller to ensure that the cpu doesn't go offline. 6730 * The caller must not hold any locks which would prevent @fn from completing. 6731 * 6732 * Return: The value @fn returns. 6733 */ 6734 long work_on_cpu_key(int cpu, long (*fn)(void *), 6735 void *arg, struct lock_class_key *key) 6736 { 6737 struct work_for_cpu wfc = { .fn = fn, .arg = arg }; 6738 6739 INIT_WORK_ONSTACK_KEY(&wfc.work, work_for_cpu_fn, key); 6740 schedule_work_on(cpu, &wfc.work); 6741 flush_work(&wfc.work); 6742 destroy_work_on_stack(&wfc.work); 6743 return wfc.ret; 6744 } 6745 EXPORT_SYMBOL_GPL(work_on_cpu_key); 6746 6747 /** 6748 * work_on_cpu_safe_key - run a function in thread context on a particular cpu 6749 * @cpu: the cpu to run on 6750 * @fn: the function to run 6751 * @arg: the function argument 6752 * @key: The lock class key for lock debugging purposes 6753 * 6754 * Disables CPU hotplug and calls work_on_cpu(). The caller must not hold 6755 * any locks which would prevent @fn from completing. 6756 * 6757 * Return: The value @fn returns. 6758 */ 6759 long work_on_cpu_safe_key(int cpu, long (*fn)(void *), 6760 void *arg, struct lock_class_key *key) 6761 { 6762 long ret = -ENODEV; 6763 6764 cpus_read_lock(); 6765 if (cpu_online(cpu)) 6766 ret = work_on_cpu_key(cpu, fn, arg, key); 6767 cpus_read_unlock(); 6768 return ret; 6769 } 6770 EXPORT_SYMBOL_GPL(work_on_cpu_safe_key); 6771 #endif /* CONFIG_SMP */ 6772 6773 #ifdef CONFIG_FREEZER 6774 6775 /** 6776 * freeze_workqueues_begin - begin freezing workqueues 6777 * 6778 * Start freezing workqueues. After this function returns, all freezable 6779 * workqueues will queue new works to their inactive_works list instead of 6780 * pool->worklist. 6781 * 6782 * CONTEXT: 6783 * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. 6784 */ 6785 void freeze_workqueues_begin(void) 6786 { 6787 struct workqueue_struct *wq; 6788 6789 mutex_lock(&wq_pool_mutex); 6790 6791 WARN_ON_ONCE(workqueue_freezing); 6792 workqueue_freezing = true; 6793 6794 list_for_each_entry(wq, &workqueues, list) { 6795 mutex_lock(&wq->mutex); 6796 wq_adjust_max_active(wq); 6797 mutex_unlock(&wq->mutex); 6798 } 6799 6800 mutex_unlock(&wq_pool_mutex); 6801 } 6802 6803 /** 6804 * freeze_workqueues_busy - are freezable workqueues still busy? 6805 * 6806 * Check whether freezing is complete. This function must be called 6807 * between freeze_workqueues_begin() and thaw_workqueues(). 6808 * 6809 * CONTEXT: 6810 * Grabs and releases wq_pool_mutex. 6811 * 6812 * Return: 6813 * %true if some freezable workqueues are still busy. %false if freezing 6814 * is complete. 6815 */ 6816 bool freeze_workqueues_busy(void) 6817 { 6818 bool busy = false; 6819 struct workqueue_struct *wq; 6820 struct pool_workqueue *pwq; 6821 6822 mutex_lock(&wq_pool_mutex); 6823 6824 WARN_ON_ONCE(!workqueue_freezing); 6825 6826 list_for_each_entry(wq, &workqueues, list) { 6827 if (!(wq->flags & WQ_FREEZABLE)) 6828 continue; 6829 /* 6830 * nr_active is monotonically decreasing. It's safe 6831 * to peek without lock. 6832 */ 6833 rcu_read_lock(); 6834 for_each_pwq(pwq, wq) { 6835 WARN_ON_ONCE(pwq->nr_active < 0); 6836 if (pwq->nr_active) { 6837 busy = true; 6838 rcu_read_unlock(); 6839 goto out_unlock; 6840 } 6841 } 6842 rcu_read_unlock(); 6843 } 6844 out_unlock: 6845 mutex_unlock(&wq_pool_mutex); 6846 return busy; 6847 } 6848 6849 /** 6850 * thaw_workqueues - thaw workqueues 6851 * 6852 * Thaw workqueues. Normal queueing is restored and all collected 6853 * frozen works are transferred to their respective pool worklists. 6854 * 6855 * CONTEXT: 6856 * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. 6857 */ 6858 void thaw_workqueues(void) 6859 { 6860 struct workqueue_struct *wq; 6861 6862 mutex_lock(&wq_pool_mutex); 6863 6864 if (!workqueue_freezing) 6865 goto out_unlock; 6866 6867 workqueue_freezing = false; 6868 6869 /* restore max_active and repopulate worklist */ 6870 list_for_each_entry(wq, &workqueues, list) { 6871 mutex_lock(&wq->mutex); 6872 wq_adjust_max_active(wq); 6873 mutex_unlock(&wq->mutex); 6874 } 6875 6876 out_unlock: 6877 mutex_unlock(&wq_pool_mutex); 6878 } 6879 #endif /* CONFIG_FREEZER */ 6880 6881 static int workqueue_apply_unbound_cpumask(const cpumask_var_t unbound_cpumask) 6882 { 6883 LIST_HEAD(ctxs); 6884 int ret = 0; 6885 struct workqueue_struct *wq; 6886 struct apply_wqattrs_ctx *ctx, *n; 6887 6888 lockdep_assert_held(&wq_pool_mutex); 6889 6890 list_for_each_entry(wq, &workqueues, list) { 6891 if (!(wq->flags & WQ_UNBOUND) || (wq->flags & __WQ_DESTROYING)) 6892 continue; 6893 6894 ctx = apply_wqattrs_prepare(wq, wq->unbound_attrs, unbound_cpumask); 6895 if (IS_ERR(ctx)) { 6896 ret = PTR_ERR(ctx); 6897 break; 6898 } 6899 6900 list_add_tail(&ctx->list, &ctxs); 6901 } 6902 6903 list_for_each_entry_safe(ctx, n, &ctxs, list) { 6904 if (!ret) 6905 apply_wqattrs_commit(ctx); 6906 apply_wqattrs_cleanup(ctx); 6907 } 6908 6909 if (!ret) { 6910 mutex_lock(&wq_pool_attach_mutex); 6911 cpumask_copy(wq_unbound_cpumask, unbound_cpumask); 6912 mutex_unlock(&wq_pool_attach_mutex); 6913 } 6914 return ret; 6915 } 6916 6917 /** 6918 * workqueue_unbound_exclude_cpumask - Exclude given CPUs from unbound cpumask 6919 * @exclude_cpumask: the cpumask to be excluded from wq_unbound_cpumask 6920 * 6921 * This function can be called from cpuset code to provide a set of isolated 6922 * CPUs that should be excluded from wq_unbound_cpumask. 6923 */ 6924 int workqueue_unbound_exclude_cpumask(cpumask_var_t exclude_cpumask) 6925 { 6926 cpumask_var_t cpumask; 6927 int ret = 0; 6928 6929 if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL)) 6930 return -ENOMEM; 6931 6932 mutex_lock(&wq_pool_mutex); 6933 6934 /* 6935 * If the operation fails, it will fall back to 6936 * wq_requested_unbound_cpumask which is initially set to 6937 * (HK_TYPE_WQ ∩ HK_TYPE_DOMAIN) house keeping mask and rewritten 6938 * by any subsequent write to workqueue/cpumask sysfs file. 6939 */ 6940 if (!cpumask_andnot(cpumask, wq_requested_unbound_cpumask, exclude_cpumask)) 6941 cpumask_copy(cpumask, wq_requested_unbound_cpumask); 6942 if (!cpumask_equal(cpumask, wq_unbound_cpumask)) 6943 ret = workqueue_apply_unbound_cpumask(cpumask); 6944 6945 /* Save the current isolated cpumask & export it via sysfs */ 6946 if (!ret) 6947 cpumask_copy(wq_isolated_cpumask, exclude_cpumask); 6948 6949 mutex_unlock(&wq_pool_mutex); 6950 free_cpumask_var(cpumask); 6951 return ret; 6952 } 6953 6954 static int parse_affn_scope(const char *val) 6955 { 6956 int i; 6957 6958 for (i = 0; i < ARRAY_SIZE(wq_affn_names); i++) { 6959 if (!strncasecmp(val, wq_affn_names[i], strlen(wq_affn_names[i]))) 6960 return i; 6961 } 6962 return -EINVAL; 6963 } 6964 6965 static int wq_affn_dfl_set(const char *val, const struct kernel_param *kp) 6966 { 6967 struct workqueue_struct *wq; 6968 int affn, cpu; 6969 6970 affn = parse_affn_scope(val); 6971 if (affn < 0) 6972 return affn; 6973 if (affn == WQ_AFFN_DFL) 6974 return -EINVAL; 6975 6976 cpus_read_lock(); 6977 mutex_lock(&wq_pool_mutex); 6978 6979 wq_affn_dfl = affn; 6980 6981 list_for_each_entry(wq, &workqueues, list) { 6982 for_each_online_cpu(cpu) 6983 unbound_wq_update_pwq(wq, cpu); 6984 } 6985 6986 mutex_unlock(&wq_pool_mutex); 6987 cpus_read_unlock(); 6988 6989 return 0; 6990 } 6991 6992 static int wq_affn_dfl_get(char *buffer, const struct kernel_param *kp) 6993 { 6994 return scnprintf(buffer, PAGE_SIZE, "%s\n", wq_affn_names[wq_affn_dfl]); 6995 } 6996 6997 static const struct kernel_param_ops wq_affn_dfl_ops = { 6998 .set = wq_affn_dfl_set, 6999 .get = wq_affn_dfl_get, 7000 }; 7001 7002 module_param_cb(default_affinity_scope, &wq_affn_dfl_ops, NULL, 0644); 7003 7004 #ifdef CONFIG_SYSFS 7005 /* 7006 * Workqueues with WQ_SYSFS flag set is visible to userland via 7007 * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the 7008 * following attributes. 7009 * 7010 * per_cpu RO bool : whether the workqueue is per-cpu or unbound 7011 * max_active RW int : maximum number of in-flight work items 7012 * 7013 * Unbound workqueues have the following extra attributes. 7014 * 7015 * nice RW int : nice value of the workers 7016 * cpumask RW mask : bitmask of allowed CPUs for the workers 7017 * affinity_scope RW str : worker CPU affinity scope (cache, numa, none) 7018 * affinity_strict RW bool : worker CPU affinity is strict 7019 */ 7020 struct wq_device { 7021 struct workqueue_struct *wq; 7022 struct device dev; 7023 }; 7024 7025 static struct workqueue_struct *dev_to_wq(struct device *dev) 7026 { 7027 struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); 7028 7029 return wq_dev->wq; 7030 } 7031 7032 static ssize_t per_cpu_show(struct device *dev, struct device_attribute *attr, 7033 char *buf) 7034 { 7035 struct workqueue_struct *wq = dev_to_wq(dev); 7036 7037 return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND)); 7038 } 7039 static DEVICE_ATTR_RO(per_cpu); 7040 7041 static ssize_t max_active_show(struct device *dev, 7042 struct device_attribute *attr, char *buf) 7043 { 7044 struct workqueue_struct *wq = dev_to_wq(dev); 7045 7046 return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active); 7047 } 7048 7049 static ssize_t max_active_store(struct device *dev, 7050 struct device_attribute *attr, const char *buf, 7051 size_t count) 7052 { 7053 struct workqueue_struct *wq = dev_to_wq(dev); 7054 int val; 7055 7056 if (sscanf(buf, "%d", &val) != 1 || val <= 0) 7057 return -EINVAL; 7058 7059 workqueue_set_max_active(wq, val); 7060 return count; 7061 } 7062 static DEVICE_ATTR_RW(max_active); 7063 7064 static struct attribute *wq_sysfs_attrs[] = { 7065 &dev_attr_per_cpu.attr, 7066 &dev_attr_max_active.attr, 7067 NULL, 7068 }; 7069 ATTRIBUTE_GROUPS(wq_sysfs); 7070 7071 static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr, 7072 char *buf) 7073 { 7074 struct workqueue_struct *wq = dev_to_wq(dev); 7075 int written; 7076 7077 mutex_lock(&wq->mutex); 7078 written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice); 7079 mutex_unlock(&wq->mutex); 7080 7081 return written; 7082 } 7083 7084 /* prepare workqueue_attrs for sysfs store operations */ 7085 static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq) 7086 { 7087 struct workqueue_attrs *attrs; 7088 7089 lockdep_assert_held(&wq_pool_mutex); 7090 7091 attrs = alloc_workqueue_attrs(); 7092 if (!attrs) 7093 return NULL; 7094 7095 copy_workqueue_attrs(attrs, wq->unbound_attrs); 7096 return attrs; 7097 } 7098 7099 static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr, 7100 const char *buf, size_t count) 7101 { 7102 struct workqueue_struct *wq = dev_to_wq(dev); 7103 struct workqueue_attrs *attrs; 7104 int ret = -ENOMEM; 7105 7106 apply_wqattrs_lock(); 7107 7108 attrs = wq_sysfs_prep_attrs(wq); 7109 if (!attrs) 7110 goto out_unlock; 7111 7112 if (sscanf(buf, "%d", &attrs->nice) == 1 && 7113 attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE) 7114 ret = apply_workqueue_attrs_locked(wq, attrs); 7115 else 7116 ret = -EINVAL; 7117 7118 out_unlock: 7119 apply_wqattrs_unlock(); 7120 free_workqueue_attrs(attrs); 7121 return ret ?: count; 7122 } 7123 7124 static ssize_t wq_cpumask_show(struct device *dev, 7125 struct device_attribute *attr, char *buf) 7126 { 7127 struct workqueue_struct *wq = dev_to_wq(dev); 7128 int written; 7129 7130 mutex_lock(&wq->mutex); 7131 written = scnprintf(buf, PAGE_SIZE, "%*pb\n", 7132 cpumask_pr_args(wq->unbound_attrs->cpumask)); 7133 mutex_unlock(&wq->mutex); 7134 return written; 7135 } 7136 7137 static ssize_t wq_cpumask_store(struct device *dev, 7138 struct device_attribute *attr, 7139 const char *buf, size_t count) 7140 { 7141 struct workqueue_struct *wq = dev_to_wq(dev); 7142 struct workqueue_attrs *attrs; 7143 int ret = -ENOMEM; 7144 7145 apply_wqattrs_lock(); 7146 7147 attrs = wq_sysfs_prep_attrs(wq); 7148 if (!attrs) 7149 goto out_unlock; 7150 7151 ret = cpumask_parse(buf, attrs->cpumask); 7152 if (!ret) 7153 ret = apply_workqueue_attrs_locked(wq, attrs); 7154 7155 out_unlock: 7156 apply_wqattrs_unlock(); 7157 free_workqueue_attrs(attrs); 7158 return ret ?: count; 7159 } 7160 7161 static ssize_t wq_affn_scope_show(struct device *dev, 7162 struct device_attribute *attr, char *buf) 7163 { 7164 struct workqueue_struct *wq = dev_to_wq(dev); 7165 int written; 7166 7167 mutex_lock(&wq->mutex); 7168 if (wq->unbound_attrs->affn_scope == WQ_AFFN_DFL) 7169 written = scnprintf(buf, PAGE_SIZE, "%s (%s)\n", 7170 wq_affn_names[WQ_AFFN_DFL], 7171 wq_affn_names[wq_affn_dfl]); 7172 else 7173 written = scnprintf(buf, PAGE_SIZE, "%s\n", 7174 wq_affn_names[wq->unbound_attrs->affn_scope]); 7175 mutex_unlock(&wq->mutex); 7176 7177 return written; 7178 } 7179 7180 static ssize_t wq_affn_scope_store(struct device *dev, 7181 struct device_attribute *attr, 7182 const char *buf, size_t count) 7183 { 7184 struct workqueue_struct *wq = dev_to_wq(dev); 7185 struct workqueue_attrs *attrs; 7186 int affn, ret = -ENOMEM; 7187 7188 affn = parse_affn_scope(buf); 7189 if (affn < 0) 7190 return affn; 7191 7192 apply_wqattrs_lock(); 7193 attrs = wq_sysfs_prep_attrs(wq); 7194 if (attrs) { 7195 attrs->affn_scope = affn; 7196 ret = apply_workqueue_attrs_locked(wq, attrs); 7197 } 7198 apply_wqattrs_unlock(); 7199 free_workqueue_attrs(attrs); 7200 return ret ?: count; 7201 } 7202 7203 static ssize_t wq_affinity_strict_show(struct device *dev, 7204 struct device_attribute *attr, char *buf) 7205 { 7206 struct workqueue_struct *wq = dev_to_wq(dev); 7207 7208 return scnprintf(buf, PAGE_SIZE, "%d\n", 7209 wq->unbound_attrs->affn_strict); 7210 } 7211 7212 static ssize_t wq_affinity_strict_store(struct device *dev, 7213 struct device_attribute *attr, 7214 const char *buf, size_t count) 7215 { 7216 struct workqueue_struct *wq = dev_to_wq(dev); 7217 struct workqueue_attrs *attrs; 7218 int v, ret = -ENOMEM; 7219 7220 if (sscanf(buf, "%d", &v) != 1) 7221 return -EINVAL; 7222 7223 apply_wqattrs_lock(); 7224 attrs = wq_sysfs_prep_attrs(wq); 7225 if (attrs) { 7226 attrs->affn_strict = (bool)v; 7227 ret = apply_workqueue_attrs_locked(wq, attrs); 7228 } 7229 apply_wqattrs_unlock(); 7230 free_workqueue_attrs(attrs); 7231 return ret ?: count; 7232 } 7233 7234 static struct device_attribute wq_sysfs_unbound_attrs[] = { 7235 __ATTR(nice, 0644, wq_nice_show, wq_nice_store), 7236 __ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store), 7237 __ATTR(affinity_scope, 0644, wq_affn_scope_show, wq_affn_scope_store), 7238 __ATTR(affinity_strict, 0644, wq_affinity_strict_show, wq_affinity_strict_store), 7239 __ATTR_NULL, 7240 }; 7241 7242 static const struct bus_type wq_subsys = { 7243 .name = "workqueue", 7244 .dev_groups = wq_sysfs_groups, 7245 }; 7246 7247 /** 7248 * workqueue_set_unbound_cpumask - Set the low-level unbound cpumask 7249 * @cpumask: the cpumask to set 7250 * 7251 * The low-level workqueues cpumask is a global cpumask that limits 7252 * the affinity of all unbound workqueues. This function check the @cpumask 7253 * and apply it to all unbound workqueues and updates all pwqs of them. 7254 * 7255 * Return: 0 - Success 7256 * -EINVAL - Invalid @cpumask 7257 * -ENOMEM - Failed to allocate memory for attrs or pwqs. 7258 */ 7259 static int workqueue_set_unbound_cpumask(cpumask_var_t cpumask) 7260 { 7261 int ret = -EINVAL; 7262 7263 /* 7264 * Not excluding isolated cpus on purpose. 7265 * If the user wishes to include them, we allow that. 7266 */ 7267 cpumask_and(cpumask, cpumask, cpu_possible_mask); 7268 if (!cpumask_empty(cpumask)) { 7269 ret = 0; 7270 apply_wqattrs_lock(); 7271 if (!cpumask_equal(cpumask, wq_unbound_cpumask)) 7272 ret = workqueue_apply_unbound_cpumask(cpumask); 7273 if (!ret) 7274 cpumask_copy(wq_requested_unbound_cpumask, cpumask); 7275 apply_wqattrs_unlock(); 7276 } 7277 7278 return ret; 7279 } 7280 7281 static ssize_t __wq_cpumask_show(struct device *dev, 7282 struct device_attribute *attr, char *buf, cpumask_var_t mask) 7283 { 7284 int written; 7285 7286 mutex_lock(&wq_pool_mutex); 7287 written = scnprintf(buf, PAGE_SIZE, "%*pb\n", cpumask_pr_args(mask)); 7288 mutex_unlock(&wq_pool_mutex); 7289 7290 return written; 7291 } 7292 7293 static ssize_t cpumask_requested_show(struct device *dev, 7294 struct device_attribute *attr, char *buf) 7295 { 7296 return __wq_cpumask_show(dev, attr, buf, wq_requested_unbound_cpumask); 7297 } 7298 static DEVICE_ATTR_RO(cpumask_requested); 7299 7300 static ssize_t cpumask_isolated_show(struct device *dev, 7301 struct device_attribute *attr, char *buf) 7302 { 7303 return __wq_cpumask_show(dev, attr, buf, wq_isolated_cpumask); 7304 } 7305 static DEVICE_ATTR_RO(cpumask_isolated); 7306 7307 static ssize_t cpumask_show(struct device *dev, 7308 struct device_attribute *attr, char *buf) 7309 { 7310 return __wq_cpumask_show(dev, attr, buf, wq_unbound_cpumask); 7311 } 7312 7313 static ssize_t cpumask_store(struct device *dev, 7314 struct device_attribute *attr, const char *buf, size_t count) 7315 { 7316 cpumask_var_t cpumask; 7317 int ret; 7318 7319 if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL)) 7320 return -ENOMEM; 7321 7322 ret = cpumask_parse(buf, cpumask); 7323 if (!ret) 7324 ret = workqueue_set_unbound_cpumask(cpumask); 7325 7326 free_cpumask_var(cpumask); 7327 return ret ? ret : count; 7328 } 7329 static DEVICE_ATTR_RW(cpumask); 7330 7331 static struct attribute *wq_sysfs_cpumask_attrs[] = { 7332 &dev_attr_cpumask.attr, 7333 &dev_attr_cpumask_requested.attr, 7334 &dev_attr_cpumask_isolated.attr, 7335 NULL, 7336 }; 7337 ATTRIBUTE_GROUPS(wq_sysfs_cpumask); 7338 7339 static int __init wq_sysfs_init(void) 7340 { 7341 return subsys_virtual_register(&wq_subsys, wq_sysfs_cpumask_groups); 7342 } 7343 core_initcall(wq_sysfs_init); 7344 7345 static void wq_device_release(struct device *dev) 7346 { 7347 struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); 7348 7349 kfree(wq_dev); 7350 } 7351 7352 /** 7353 * workqueue_sysfs_register - make a workqueue visible in sysfs 7354 * @wq: the workqueue to register 7355 * 7356 * Expose @wq in sysfs under /sys/bus/workqueue/devices. 7357 * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set 7358 * which is the preferred method. 7359 * 7360 * Workqueue user should use this function directly iff it wants to apply 7361 * workqueue_attrs before making the workqueue visible in sysfs; otherwise, 7362 * apply_workqueue_attrs() may race against userland updating the 7363 * attributes. 7364 * 7365 * Return: 0 on success, -errno on failure. 7366 */ 7367 int workqueue_sysfs_register(struct workqueue_struct *wq) 7368 { 7369 struct wq_device *wq_dev; 7370 int ret; 7371 7372 /* 7373 * Adjusting max_active breaks ordering guarantee. Disallow exposing 7374 * ordered workqueues. 7375 */ 7376 if (WARN_ON(wq->flags & __WQ_ORDERED)) 7377 return -EINVAL; 7378 7379 wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL); 7380 if (!wq_dev) 7381 return -ENOMEM; 7382 7383 wq_dev->wq = wq; 7384 wq_dev->dev.bus = &wq_subsys; 7385 wq_dev->dev.release = wq_device_release; 7386 dev_set_name(&wq_dev->dev, "%s", wq->name); 7387 7388 /* 7389 * unbound_attrs are created separately. Suppress uevent until 7390 * everything is ready. 7391 */ 7392 dev_set_uevent_suppress(&wq_dev->dev, true); 7393 7394 ret = device_register(&wq_dev->dev); 7395 if (ret) { 7396 put_device(&wq_dev->dev); 7397 wq->wq_dev = NULL; 7398 return ret; 7399 } 7400 7401 if (wq->flags & WQ_UNBOUND) { 7402 struct device_attribute *attr; 7403 7404 for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) { 7405 ret = device_create_file(&wq_dev->dev, attr); 7406 if (ret) { 7407 device_unregister(&wq_dev->dev); 7408 wq->wq_dev = NULL; 7409 return ret; 7410 } 7411 } 7412 } 7413 7414 dev_set_uevent_suppress(&wq_dev->dev, false); 7415 kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD); 7416 return 0; 7417 } 7418 7419 /** 7420 * workqueue_sysfs_unregister - undo workqueue_sysfs_register() 7421 * @wq: the workqueue to unregister 7422 * 7423 * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister. 7424 */ 7425 static void workqueue_sysfs_unregister(struct workqueue_struct *wq) 7426 { 7427 struct wq_device *wq_dev = wq->wq_dev; 7428 7429 if (!wq->wq_dev) 7430 return; 7431 7432 wq->wq_dev = NULL; 7433 device_unregister(&wq_dev->dev); 7434 } 7435 #else /* CONFIG_SYSFS */ 7436 static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { } 7437 #endif /* CONFIG_SYSFS */ 7438 7439 /* 7440 * Workqueue watchdog. 7441 * 7442 * Stall may be caused by various bugs - missing WQ_MEM_RECLAIM, illegal 7443 * flush dependency, a concurrency managed work item which stays RUNNING 7444 * indefinitely. Workqueue stalls can be very difficult to debug as the 7445 * usual warning mechanisms don't trigger and internal workqueue state is 7446 * largely opaque. 7447 * 7448 * Workqueue watchdog monitors all worker pools periodically and dumps 7449 * state if some pools failed to make forward progress for a while where 7450 * forward progress is defined as the first item on ->worklist changing. 7451 * 7452 * This mechanism is controlled through the kernel parameter 7453 * "workqueue.watchdog_thresh" which can be updated at runtime through the 7454 * corresponding sysfs parameter file. 7455 */ 7456 #ifdef CONFIG_WQ_WATCHDOG 7457 7458 static unsigned long wq_watchdog_thresh = 30; 7459 static struct timer_list wq_watchdog_timer; 7460 7461 static unsigned long wq_watchdog_touched = INITIAL_JIFFIES; 7462 static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES; 7463 7464 static unsigned int wq_panic_on_stall; 7465 module_param_named(panic_on_stall, wq_panic_on_stall, uint, 0644); 7466 7467 /* 7468 * Show workers that might prevent the processing of pending work items. 7469 * The only candidates are CPU-bound workers in the running state. 7470 * Pending work items should be handled by another idle worker 7471 * in all other situations. 7472 */ 7473 static void show_cpu_pool_hog(struct worker_pool *pool) 7474 { 7475 struct worker *worker; 7476 unsigned long irq_flags; 7477 int bkt; 7478 7479 raw_spin_lock_irqsave(&pool->lock, irq_flags); 7480 7481 hash_for_each(pool->busy_hash, bkt, worker, hentry) { 7482 if (task_is_running(worker->task)) { 7483 /* 7484 * Defer printing to avoid deadlocks in console 7485 * drivers that queue work while holding locks 7486 * also taken in their write paths. 7487 */ 7488 printk_deferred_enter(); 7489 7490 pr_info("pool %d:\n", pool->id); 7491 sched_show_task(worker->task); 7492 7493 printk_deferred_exit(); 7494 } 7495 } 7496 7497 raw_spin_unlock_irqrestore(&pool->lock, irq_flags); 7498 } 7499 7500 static void show_cpu_pools_hogs(void) 7501 { 7502 struct worker_pool *pool; 7503 int pi; 7504 7505 pr_info("Showing backtraces of running workers in stalled CPU-bound worker pools:\n"); 7506 7507 rcu_read_lock(); 7508 7509 for_each_pool(pool, pi) { 7510 if (pool->cpu_stall) 7511 show_cpu_pool_hog(pool); 7512 7513 } 7514 7515 rcu_read_unlock(); 7516 } 7517 7518 static void panic_on_wq_watchdog(void) 7519 { 7520 static unsigned int wq_stall; 7521 7522 if (wq_panic_on_stall) { 7523 wq_stall++; 7524 BUG_ON(wq_stall >= wq_panic_on_stall); 7525 } 7526 } 7527 7528 static void wq_watchdog_reset_touched(void) 7529 { 7530 int cpu; 7531 7532 wq_watchdog_touched = jiffies; 7533 for_each_possible_cpu(cpu) 7534 per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies; 7535 } 7536 7537 static void wq_watchdog_timer_fn(struct timer_list *unused) 7538 { 7539 unsigned long thresh = READ_ONCE(wq_watchdog_thresh) * HZ; 7540 bool lockup_detected = false; 7541 bool cpu_pool_stall = false; 7542 unsigned long now = jiffies; 7543 struct worker_pool *pool; 7544 int pi; 7545 7546 if (!thresh) 7547 return; 7548 7549 rcu_read_lock(); 7550 7551 for_each_pool(pool, pi) { 7552 unsigned long pool_ts, touched, ts; 7553 7554 pool->cpu_stall = false; 7555 if (list_empty(&pool->worklist)) 7556 continue; 7557 7558 /* 7559 * If a virtual machine is stopped by the host it can look to 7560 * the watchdog like a stall. 7561 */ 7562 kvm_check_and_clear_guest_paused(); 7563 7564 /* get the latest of pool and touched timestamps */ 7565 if (pool->cpu >= 0) 7566 touched = READ_ONCE(per_cpu(wq_watchdog_touched_cpu, pool->cpu)); 7567 else 7568 touched = READ_ONCE(wq_watchdog_touched); 7569 pool_ts = READ_ONCE(pool->watchdog_ts); 7570 7571 if (time_after(pool_ts, touched)) 7572 ts = pool_ts; 7573 else 7574 ts = touched; 7575 7576 /* did we stall? */ 7577 if (time_after(now, ts + thresh)) { 7578 lockup_detected = true; 7579 if (pool->cpu >= 0 && !(pool->flags & POOL_BH)) { 7580 pool->cpu_stall = true; 7581 cpu_pool_stall = true; 7582 } 7583 pr_emerg("BUG: workqueue lockup - pool"); 7584 pr_cont_pool_info(pool); 7585 pr_cont(" stuck for %us!\n", 7586 jiffies_to_msecs(now - pool_ts) / 1000); 7587 } 7588 7589 7590 } 7591 7592 rcu_read_unlock(); 7593 7594 if (lockup_detected) 7595 show_all_workqueues(); 7596 7597 if (cpu_pool_stall) 7598 show_cpu_pools_hogs(); 7599 7600 if (lockup_detected) 7601 panic_on_wq_watchdog(); 7602 7603 wq_watchdog_reset_touched(); 7604 mod_timer(&wq_watchdog_timer, jiffies + thresh); 7605 } 7606 7607 notrace void wq_watchdog_touch(int cpu) 7608 { 7609 unsigned long thresh = READ_ONCE(wq_watchdog_thresh) * HZ; 7610 unsigned long touch_ts = READ_ONCE(wq_watchdog_touched); 7611 unsigned long now = jiffies; 7612 7613 if (cpu >= 0) 7614 per_cpu(wq_watchdog_touched_cpu, cpu) = now; 7615 else 7616 WARN_ONCE(1, "%s should be called with valid CPU", __func__); 7617 7618 /* Don't unnecessarily store to global cacheline */ 7619 if (time_after(now, touch_ts + thresh / 4)) 7620 WRITE_ONCE(wq_watchdog_touched, jiffies); 7621 } 7622 7623 static void wq_watchdog_set_thresh(unsigned long thresh) 7624 { 7625 wq_watchdog_thresh = 0; 7626 del_timer_sync(&wq_watchdog_timer); 7627 7628 if (thresh) { 7629 wq_watchdog_thresh = thresh; 7630 wq_watchdog_reset_touched(); 7631 mod_timer(&wq_watchdog_timer, jiffies + thresh * HZ); 7632 } 7633 } 7634 7635 static int wq_watchdog_param_set_thresh(const char *val, 7636 const struct kernel_param *kp) 7637 { 7638 unsigned long thresh; 7639 int ret; 7640 7641 ret = kstrtoul(val, 0, &thresh); 7642 if (ret) 7643 return ret; 7644 7645 if (system_wq) 7646 wq_watchdog_set_thresh(thresh); 7647 else 7648 wq_watchdog_thresh = thresh; 7649 7650 return 0; 7651 } 7652 7653 static const struct kernel_param_ops wq_watchdog_thresh_ops = { 7654 .set = wq_watchdog_param_set_thresh, 7655 .get = param_get_ulong, 7656 }; 7657 7658 module_param_cb(watchdog_thresh, &wq_watchdog_thresh_ops, &wq_watchdog_thresh, 7659 0644); 7660 7661 static void wq_watchdog_init(void) 7662 { 7663 timer_setup(&wq_watchdog_timer, wq_watchdog_timer_fn, TIMER_DEFERRABLE); 7664 wq_watchdog_set_thresh(wq_watchdog_thresh); 7665 } 7666 7667 #else /* CONFIG_WQ_WATCHDOG */ 7668 7669 static inline void wq_watchdog_init(void) { } 7670 7671 #endif /* CONFIG_WQ_WATCHDOG */ 7672 7673 static void bh_pool_kick_normal(struct irq_work *irq_work) 7674 { 7675 raise_softirq_irqoff(TASKLET_SOFTIRQ); 7676 } 7677 7678 static void bh_pool_kick_highpri(struct irq_work *irq_work) 7679 { 7680 raise_softirq_irqoff(HI_SOFTIRQ); 7681 } 7682 7683 static void __init restrict_unbound_cpumask(const char *name, const struct cpumask *mask) 7684 { 7685 if (!cpumask_intersects(wq_unbound_cpumask, mask)) { 7686 pr_warn("workqueue: Restricting unbound_cpumask (%*pb) with %s (%*pb) leaves no CPU, ignoring\n", 7687 cpumask_pr_args(wq_unbound_cpumask), name, cpumask_pr_args(mask)); 7688 return; 7689 } 7690 7691 cpumask_and(wq_unbound_cpumask, wq_unbound_cpumask, mask); 7692 } 7693 7694 static void __init init_cpu_worker_pool(struct worker_pool *pool, int cpu, int nice) 7695 { 7696 BUG_ON(init_worker_pool(pool)); 7697 pool->cpu = cpu; 7698 cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu)); 7699 cpumask_copy(pool->attrs->__pod_cpumask, cpumask_of(cpu)); 7700 pool->attrs->nice = nice; 7701 pool->attrs->affn_strict = true; 7702 pool->node = cpu_to_node(cpu); 7703 7704 /* alloc pool ID */ 7705 mutex_lock(&wq_pool_mutex); 7706 BUG_ON(worker_pool_assign_id(pool)); 7707 mutex_unlock(&wq_pool_mutex); 7708 } 7709 7710 /** 7711 * workqueue_init_early - early init for workqueue subsystem 7712 * 7713 * This is the first step of three-staged workqueue subsystem initialization and 7714 * invoked as soon as the bare basics - memory allocation, cpumasks and idr are 7715 * up. It sets up all the data structures and system workqueues and allows early 7716 * boot code to create workqueues and queue/cancel work items. Actual work item 7717 * execution starts only after kthreads can be created and scheduled right 7718 * before early initcalls. 7719 */ 7720 void __init workqueue_init_early(void) 7721 { 7722 struct wq_pod_type *pt = &wq_pod_types[WQ_AFFN_SYSTEM]; 7723 int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL }; 7724 void (*irq_work_fns[2])(struct irq_work *) = { bh_pool_kick_normal, 7725 bh_pool_kick_highpri }; 7726 int i, cpu; 7727 7728 BUILD_BUG_ON(__alignof__(struct pool_workqueue) < __alignof__(long long)); 7729 7730 BUG_ON(!alloc_cpumask_var(&wq_online_cpumask, GFP_KERNEL)); 7731 BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask, GFP_KERNEL)); 7732 BUG_ON(!alloc_cpumask_var(&wq_requested_unbound_cpumask, GFP_KERNEL)); 7733 BUG_ON(!zalloc_cpumask_var(&wq_isolated_cpumask, GFP_KERNEL)); 7734 7735 cpumask_copy(wq_online_cpumask, cpu_online_mask); 7736 cpumask_copy(wq_unbound_cpumask, cpu_possible_mask); 7737 restrict_unbound_cpumask("HK_TYPE_WQ", housekeeping_cpumask(HK_TYPE_WQ)); 7738 restrict_unbound_cpumask("HK_TYPE_DOMAIN", housekeeping_cpumask(HK_TYPE_DOMAIN)); 7739 if (!cpumask_empty(&wq_cmdline_cpumask)) 7740 restrict_unbound_cpumask("workqueue.unbound_cpus", &wq_cmdline_cpumask); 7741 7742 cpumask_copy(wq_requested_unbound_cpumask, wq_unbound_cpumask); 7743 7744 pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC); 7745 7746 unbound_wq_update_pwq_attrs_buf = alloc_workqueue_attrs(); 7747 BUG_ON(!unbound_wq_update_pwq_attrs_buf); 7748 7749 /* 7750 * If nohz_full is enabled, set power efficient workqueue as unbound. 7751 * This allows workqueue items to be moved to HK CPUs. 7752 */ 7753 if (housekeeping_enabled(HK_TYPE_TICK)) 7754 wq_power_efficient = true; 7755 7756 /* initialize WQ_AFFN_SYSTEM pods */ 7757 pt->pod_cpus = kcalloc(1, sizeof(pt->pod_cpus[0]), GFP_KERNEL); 7758 pt->pod_node = kcalloc(1, sizeof(pt->pod_node[0]), GFP_KERNEL); 7759 pt->cpu_pod = kcalloc(nr_cpu_ids, sizeof(pt->cpu_pod[0]), GFP_KERNEL); 7760 BUG_ON(!pt->pod_cpus || !pt->pod_node || !pt->cpu_pod); 7761 7762 BUG_ON(!zalloc_cpumask_var_node(&pt->pod_cpus[0], GFP_KERNEL, NUMA_NO_NODE)); 7763 7764 pt->nr_pods = 1; 7765 cpumask_copy(pt->pod_cpus[0], cpu_possible_mask); 7766 pt->pod_node[0] = NUMA_NO_NODE; 7767 pt->cpu_pod[0] = 0; 7768 7769 /* initialize BH and CPU pools */ 7770 for_each_possible_cpu(cpu) { 7771 struct worker_pool *pool; 7772 7773 i = 0; 7774 for_each_bh_worker_pool(pool, cpu) { 7775 init_cpu_worker_pool(pool, cpu, std_nice[i]); 7776 pool->flags |= POOL_BH; 7777 init_irq_work(bh_pool_irq_work(pool), irq_work_fns[i]); 7778 i++; 7779 } 7780 7781 i = 0; 7782 for_each_cpu_worker_pool(pool, cpu) 7783 init_cpu_worker_pool(pool, cpu, std_nice[i++]); 7784 } 7785 7786 /* create default unbound and ordered wq attrs */ 7787 for (i = 0; i < NR_STD_WORKER_POOLS; i++) { 7788 struct workqueue_attrs *attrs; 7789 7790 BUG_ON(!(attrs = alloc_workqueue_attrs())); 7791 attrs->nice = std_nice[i]; 7792 unbound_std_wq_attrs[i] = attrs; 7793 7794 /* 7795 * An ordered wq should have only one pwq as ordering is 7796 * guaranteed by max_active which is enforced by pwqs. 7797 */ 7798 BUG_ON(!(attrs = alloc_workqueue_attrs())); 7799 attrs->nice = std_nice[i]; 7800 attrs->ordered = true; 7801 ordered_wq_attrs[i] = attrs; 7802 } 7803 7804 system_wq = alloc_workqueue("events", 0, 0); 7805 system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0); 7806 system_long_wq = alloc_workqueue("events_long", 0, 0); 7807 system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, 7808 WQ_MAX_ACTIVE); 7809 system_freezable_wq = alloc_workqueue("events_freezable", 7810 WQ_FREEZABLE, 0); 7811 system_power_efficient_wq = alloc_workqueue("events_power_efficient", 7812 WQ_POWER_EFFICIENT, 0); 7813 system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_pwr_efficient", 7814 WQ_FREEZABLE | WQ_POWER_EFFICIENT, 7815 0); 7816 system_bh_wq = alloc_workqueue("events_bh", WQ_BH, 0); 7817 system_bh_highpri_wq = alloc_workqueue("events_bh_highpri", 7818 WQ_BH | WQ_HIGHPRI, 0); 7819 BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq || 7820 !system_unbound_wq || !system_freezable_wq || 7821 !system_power_efficient_wq || 7822 !system_freezable_power_efficient_wq || 7823 !system_bh_wq || !system_bh_highpri_wq); 7824 } 7825 7826 static void __init wq_cpu_intensive_thresh_init(void) 7827 { 7828 unsigned long thresh; 7829 unsigned long bogo; 7830 7831 pwq_release_worker = kthread_create_worker(0, "pool_workqueue_release"); 7832 BUG_ON(IS_ERR(pwq_release_worker)); 7833 7834 /* if the user set it to a specific value, keep it */ 7835 if (wq_cpu_intensive_thresh_us != ULONG_MAX) 7836 return; 7837 7838 /* 7839 * The default of 10ms is derived from the fact that most modern (as of 7840 * 2023) processors can do a lot in 10ms and that it's just below what 7841 * most consider human-perceivable. However, the kernel also runs on a 7842 * lot slower CPUs including microcontrollers where the threshold is way 7843 * too low. 7844 * 7845 * Let's scale up the threshold upto 1 second if BogoMips is below 4000. 7846 * This is by no means accurate but it doesn't have to be. The mechanism 7847 * is still useful even when the threshold is fully scaled up. Also, as 7848 * the reports would usually be applicable to everyone, some machines 7849 * operating on longer thresholds won't significantly diminish their 7850 * usefulness. 7851 */ 7852 thresh = 10 * USEC_PER_MSEC; 7853 7854 /* see init/calibrate.c for lpj -> BogoMIPS calculation */ 7855 bogo = max_t(unsigned long, loops_per_jiffy / 500000 * HZ, 1); 7856 if (bogo < 4000) 7857 thresh = min_t(unsigned long, thresh * 4000 / bogo, USEC_PER_SEC); 7858 7859 pr_debug("wq_cpu_intensive_thresh: lpj=%lu BogoMIPS=%lu thresh_us=%lu\n", 7860 loops_per_jiffy, bogo, thresh); 7861 7862 wq_cpu_intensive_thresh_us = thresh; 7863 } 7864 7865 /** 7866 * workqueue_init - bring workqueue subsystem fully online 7867 * 7868 * This is the second step of three-staged workqueue subsystem initialization 7869 * and invoked as soon as kthreads can be created and scheduled. Workqueues have 7870 * been created and work items queued on them, but there are no kworkers 7871 * executing the work items yet. Populate the worker pools with the initial 7872 * workers and enable future kworker creations. 7873 */ 7874 void __init workqueue_init(void) 7875 { 7876 struct workqueue_struct *wq; 7877 struct worker_pool *pool; 7878 int cpu, bkt; 7879 7880 wq_cpu_intensive_thresh_init(); 7881 7882 mutex_lock(&wq_pool_mutex); 7883 7884 /* 7885 * Per-cpu pools created earlier could be missing node hint. Fix them 7886 * up. Also, create a rescuer for workqueues that requested it. 7887 */ 7888 for_each_possible_cpu(cpu) { 7889 for_each_bh_worker_pool(pool, cpu) 7890 pool->node = cpu_to_node(cpu); 7891 for_each_cpu_worker_pool(pool, cpu) 7892 pool->node = cpu_to_node(cpu); 7893 } 7894 7895 list_for_each_entry(wq, &workqueues, list) { 7896 WARN(init_rescuer(wq), 7897 "workqueue: failed to create early rescuer for %s", 7898 wq->name); 7899 } 7900 7901 mutex_unlock(&wq_pool_mutex); 7902 7903 /* 7904 * Create the initial workers. A BH pool has one pseudo worker that 7905 * represents the shared BH execution context and thus doesn't get 7906 * affected by hotplug events. Create the BH pseudo workers for all 7907 * possible CPUs here. 7908 */ 7909 for_each_possible_cpu(cpu) 7910 for_each_bh_worker_pool(pool, cpu) 7911 BUG_ON(!create_worker(pool)); 7912 7913 for_each_online_cpu(cpu) { 7914 for_each_cpu_worker_pool(pool, cpu) { 7915 pool->flags &= ~POOL_DISASSOCIATED; 7916 BUG_ON(!create_worker(pool)); 7917 } 7918 } 7919 7920 hash_for_each(unbound_pool_hash, bkt, pool, hash_node) 7921 BUG_ON(!create_worker(pool)); 7922 7923 wq_online = true; 7924 wq_watchdog_init(); 7925 } 7926 7927 /* 7928 * Initialize @pt by first initializing @pt->cpu_pod[] with pod IDs according to 7929 * @cpu_shares_pod(). Each subset of CPUs that share a pod is assigned a unique 7930 * and consecutive pod ID. The rest of @pt is initialized accordingly. 7931 */ 7932 static void __init init_pod_type(struct wq_pod_type *pt, 7933 bool (*cpus_share_pod)(int, int)) 7934 { 7935 int cur, pre, cpu, pod; 7936 7937 pt->nr_pods = 0; 7938 7939 /* init @pt->cpu_pod[] according to @cpus_share_pod() */ 7940 pt->cpu_pod = kcalloc(nr_cpu_ids, sizeof(pt->cpu_pod[0]), GFP_KERNEL); 7941 BUG_ON(!pt->cpu_pod); 7942 7943 for_each_possible_cpu(cur) { 7944 for_each_possible_cpu(pre) { 7945 if (pre >= cur) { 7946 pt->cpu_pod[cur] = pt->nr_pods++; 7947 break; 7948 } 7949 if (cpus_share_pod(cur, pre)) { 7950 pt->cpu_pod[cur] = pt->cpu_pod[pre]; 7951 break; 7952 } 7953 } 7954 } 7955 7956 /* init the rest to match @pt->cpu_pod[] */ 7957 pt->pod_cpus = kcalloc(pt->nr_pods, sizeof(pt->pod_cpus[0]), GFP_KERNEL); 7958 pt->pod_node = kcalloc(pt->nr_pods, sizeof(pt->pod_node[0]), GFP_KERNEL); 7959 BUG_ON(!pt->pod_cpus || !pt->pod_node); 7960 7961 for (pod = 0; pod < pt->nr_pods; pod++) 7962 BUG_ON(!zalloc_cpumask_var(&pt->pod_cpus[pod], GFP_KERNEL)); 7963 7964 for_each_possible_cpu(cpu) { 7965 cpumask_set_cpu(cpu, pt->pod_cpus[pt->cpu_pod[cpu]]); 7966 pt->pod_node[pt->cpu_pod[cpu]] = cpu_to_node(cpu); 7967 } 7968 } 7969 7970 static bool __init cpus_dont_share(int cpu0, int cpu1) 7971 { 7972 return false; 7973 } 7974 7975 static bool __init cpus_share_smt(int cpu0, int cpu1) 7976 { 7977 #ifdef CONFIG_SCHED_SMT 7978 return cpumask_test_cpu(cpu0, cpu_smt_mask(cpu1)); 7979 #else 7980 return false; 7981 #endif 7982 } 7983 7984 static bool __init cpus_share_numa(int cpu0, int cpu1) 7985 { 7986 return cpu_to_node(cpu0) == cpu_to_node(cpu1); 7987 } 7988 7989 /** 7990 * workqueue_init_topology - initialize CPU pods for unbound workqueues 7991 * 7992 * This is the third step of three-staged workqueue subsystem initialization and 7993 * invoked after SMP and topology information are fully initialized. It 7994 * initializes the unbound CPU pods accordingly. 7995 */ 7996 void __init workqueue_init_topology(void) 7997 { 7998 struct workqueue_struct *wq; 7999 int cpu; 8000 8001 init_pod_type(&wq_pod_types[WQ_AFFN_CPU], cpus_dont_share); 8002 init_pod_type(&wq_pod_types[WQ_AFFN_SMT], cpus_share_smt); 8003 init_pod_type(&wq_pod_types[WQ_AFFN_CACHE], cpus_share_cache); 8004 init_pod_type(&wq_pod_types[WQ_AFFN_NUMA], cpus_share_numa); 8005 8006 wq_topo_initialized = true; 8007 8008 mutex_lock(&wq_pool_mutex); 8009 8010 /* 8011 * Workqueues allocated earlier would have all CPUs sharing the default 8012 * worker pool. Explicitly call unbound_wq_update_pwq() on all workqueue 8013 * and CPU combinations to apply per-pod sharing. 8014 */ 8015 list_for_each_entry(wq, &workqueues, list) { 8016 for_each_online_cpu(cpu) 8017 unbound_wq_update_pwq(wq, cpu); 8018 if (wq->flags & WQ_UNBOUND) { 8019 mutex_lock(&wq->mutex); 8020 wq_update_node_max_active(wq, -1); 8021 mutex_unlock(&wq->mutex); 8022 } 8023 } 8024 8025 mutex_unlock(&wq_pool_mutex); 8026 } 8027 8028 void __warn_flushing_systemwide_wq(void) 8029 { 8030 pr_warn("WARNING: Flushing system-wide workqueues will be prohibited in near future.\n"); 8031 dump_stack(); 8032 } 8033 EXPORT_SYMBOL(__warn_flushing_systemwide_wq); 8034 8035 static int __init workqueue_unbound_cpus_setup(char *str) 8036 { 8037 if (cpulist_parse(str, &wq_cmdline_cpumask) < 0) { 8038 cpumask_clear(&wq_cmdline_cpumask); 8039 pr_warn("workqueue.unbound_cpus: incorrect CPU range, using default\n"); 8040 } 8041 8042 return 1; 8043 } 8044 __setup("workqueue.unbound_cpus=", workqueue_unbound_cpus_setup); 8045