1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Kernel internal timers 4 * 5 * Copyright (C) 1991, 1992 Linus Torvalds 6 * 7 * 1997-01-28 Modified by Finn Arne Gangstad to make timers scale better. 8 * 9 * 1997-09-10 Updated NTP code according to technical memorandum Jan '96 10 * "A Kernel Model for Precision Timekeeping" by Dave Mills 11 * 1998-12-24 Fixed a xtime SMP race (we need the xtime_lock rw spinlock to 12 * serialize accesses to xtime/lost_ticks). 13 * Copyright (C) 1998 Andrea Arcangeli 14 * 1999-03-10 Improved NTP compatibility by Ulrich Windl 15 * 2002-05-31 Move sys_sysinfo here and make its locking sane, Robert Love 16 * 2000-10-05 Implemented scalable SMP per-CPU timer handling. 17 * Copyright (C) 2000, 2001, 2002 Ingo Molnar 18 * Designed by David S. Miller, Alexey Kuznetsov and Ingo Molnar 19 */ 20 21 #include <linux/kernel_stat.h> 22 #include <linux/export.h> 23 #include <linux/interrupt.h> 24 #include <linux/percpu.h> 25 #include <linux/init.h> 26 #include <linux/mm.h> 27 #include <linux/swap.h> 28 #include <linux/pid_namespace.h> 29 #include <linux/notifier.h> 30 #include <linux/thread_info.h> 31 #include <linux/time.h> 32 #include <linux/jiffies.h> 33 #include <linux/posix-timers.h> 34 #include <linux/cpu.h> 35 #include <linux/syscalls.h> 36 #include <linux/delay.h> 37 #include <linux/tick.h> 38 #include <linux/kallsyms.h> 39 #include <linux/irq_work.h> 40 #include <linux/sched/signal.h> 41 #include <linux/sched/sysctl.h> 42 #include <linux/sched/nohz.h> 43 #include <linux/sched/debug.h> 44 #include <linux/slab.h> 45 #include <linux/compat.h> 46 #include <linux/random.h> 47 48 #include <linux/uaccess.h> 49 #include <asm/unistd.h> 50 #include <asm/div64.h> 51 #include <asm/timex.h> 52 #include <asm/io.h> 53 54 #include "tick-internal.h" 55 56 #define CREATE_TRACE_POINTS 57 #include <trace/events/timer.h> 58 59 __visible u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES; 60 61 EXPORT_SYMBOL(jiffies_64); 62 63 /* 64 * The timer wheel has LVL_DEPTH array levels. Each level provides an array of 65 * LVL_SIZE buckets. Each level is driven by its own clock and therefor each 66 * level has a different granularity. 67 * 68 * The level granularity is: LVL_CLK_DIV ^ lvl 69 * The level clock frequency is: HZ / (LVL_CLK_DIV ^ level) 70 * 71 * The array level of a newly armed timer depends on the relative expiry 72 * time. The farther the expiry time is away the higher the array level and 73 * therefor the granularity becomes. 74 * 75 * Contrary to the original timer wheel implementation, which aims for 'exact' 76 * expiry of the timers, this implementation removes the need for recascading 77 * the timers into the lower array levels. The previous 'classic' timer wheel 78 * implementation of the kernel already violated the 'exact' expiry by adding 79 * slack to the expiry time to provide batched expiration. The granularity 80 * levels provide implicit batching. 81 * 82 * This is an optimization of the original timer wheel implementation for the 83 * majority of the timer wheel use cases: timeouts. The vast majority of 84 * timeout timers (networking, disk I/O ...) are canceled before expiry. If 85 * the timeout expires it indicates that normal operation is disturbed, so it 86 * does not matter much whether the timeout comes with a slight delay. 87 * 88 * The only exception to this are networking timers with a small expiry 89 * time. They rely on the granularity. Those fit into the first wheel level, 90 * which has HZ granularity. 91 * 92 * We don't have cascading anymore. timers with a expiry time above the 93 * capacity of the last wheel level are force expired at the maximum timeout 94 * value of the last wheel level. From data sampling we know that the maximum 95 * value observed is 5 days (network connection tracking), so this should not 96 * be an issue. 97 * 98 * The currently chosen array constants values are a good compromise between 99 * array size and granularity. 100 * 101 * This results in the following granularity and range levels: 102 * 103 * HZ 1000 steps 104 * Level Offset Granularity Range 105 * 0 0 1 ms 0 ms - 63 ms 106 * 1 64 8 ms 64 ms - 511 ms 107 * 2 128 64 ms 512 ms - 4095 ms (512ms - ~4s) 108 * 3 192 512 ms 4096 ms - 32767 ms (~4s - ~32s) 109 * 4 256 4096 ms (~4s) 32768 ms - 262143 ms (~32s - ~4m) 110 * 5 320 32768 ms (~32s) 262144 ms - 2097151 ms (~4m - ~34m) 111 * 6 384 262144 ms (~4m) 2097152 ms - 16777215 ms (~34m - ~4h) 112 * 7 448 2097152 ms (~34m) 16777216 ms - 134217727 ms (~4h - ~1d) 113 * 8 512 16777216 ms (~4h) 134217728 ms - 1073741822 ms (~1d - ~12d) 114 * 115 * HZ 300 116 * Level Offset Granularity Range 117 * 0 0 3 ms 0 ms - 210 ms 118 * 1 64 26 ms 213 ms - 1703 ms (213ms - ~1s) 119 * 2 128 213 ms 1706 ms - 13650 ms (~1s - ~13s) 120 * 3 192 1706 ms (~1s) 13653 ms - 109223 ms (~13s - ~1m) 121 * 4 256 13653 ms (~13s) 109226 ms - 873810 ms (~1m - ~14m) 122 * 5 320 109226 ms (~1m) 873813 ms - 6990503 ms (~14m - ~1h) 123 * 6 384 873813 ms (~14m) 6990506 ms - 55924050 ms (~1h - ~15h) 124 * 7 448 6990506 ms (~1h) 55924053 ms - 447392423 ms (~15h - ~5d) 125 * 8 512 55924053 ms (~15h) 447392426 ms - 3579139406 ms (~5d - ~41d) 126 * 127 * HZ 250 128 * Level Offset Granularity Range 129 * 0 0 4 ms 0 ms - 255 ms 130 * 1 64 32 ms 256 ms - 2047 ms (256ms - ~2s) 131 * 2 128 256 ms 2048 ms - 16383 ms (~2s - ~16s) 132 * 3 192 2048 ms (~2s) 16384 ms - 131071 ms (~16s - ~2m) 133 * 4 256 16384 ms (~16s) 131072 ms - 1048575 ms (~2m - ~17m) 134 * 5 320 131072 ms (~2m) 1048576 ms - 8388607 ms (~17m - ~2h) 135 * 6 384 1048576 ms (~17m) 8388608 ms - 67108863 ms (~2h - ~18h) 136 * 7 448 8388608 ms (~2h) 67108864 ms - 536870911 ms (~18h - ~6d) 137 * 8 512 67108864 ms (~18h) 536870912 ms - 4294967288 ms (~6d - ~49d) 138 * 139 * HZ 100 140 * Level Offset Granularity Range 141 * 0 0 10 ms 0 ms - 630 ms 142 * 1 64 80 ms 640 ms - 5110 ms (640ms - ~5s) 143 * 2 128 640 ms 5120 ms - 40950 ms (~5s - ~40s) 144 * 3 192 5120 ms (~5s) 40960 ms - 327670 ms (~40s - ~5m) 145 * 4 256 40960 ms (~40s) 327680 ms - 2621430 ms (~5m - ~43m) 146 * 5 320 327680 ms (~5m) 2621440 ms - 20971510 ms (~43m - ~5h) 147 * 6 384 2621440 ms (~43m) 20971520 ms - 167772150 ms (~5h - ~1d) 148 * 7 448 20971520 ms (~5h) 167772160 ms - 1342177270 ms (~1d - ~15d) 149 */ 150 151 /* Clock divisor for the next level */ 152 #define LVL_CLK_SHIFT 3 153 #define LVL_CLK_DIV (1UL << LVL_CLK_SHIFT) 154 #define LVL_CLK_MASK (LVL_CLK_DIV - 1) 155 #define LVL_SHIFT(n) ((n) * LVL_CLK_SHIFT) 156 #define LVL_GRAN(n) (1UL << LVL_SHIFT(n)) 157 158 /* 159 * The time start value for each level to select the bucket at enqueue 160 * time. We start from the last possible delta of the previous level 161 * so that we can later add an extra LVL_GRAN(n) to n (see calc_index()). 162 */ 163 #define LVL_START(n) ((LVL_SIZE - 1) << (((n) - 1) * LVL_CLK_SHIFT)) 164 165 /* Size of each clock level */ 166 #define LVL_BITS 6 167 #define LVL_SIZE (1UL << LVL_BITS) 168 #define LVL_MASK (LVL_SIZE - 1) 169 #define LVL_OFFS(n) ((n) * LVL_SIZE) 170 171 /* Level depth */ 172 #if HZ > 100 173 # define LVL_DEPTH 9 174 # else 175 # define LVL_DEPTH 8 176 #endif 177 178 /* The cutoff (max. capacity of the wheel) */ 179 #define WHEEL_TIMEOUT_CUTOFF (LVL_START(LVL_DEPTH)) 180 #define WHEEL_TIMEOUT_MAX (WHEEL_TIMEOUT_CUTOFF - LVL_GRAN(LVL_DEPTH - 1)) 181 182 /* 183 * The resulting wheel size. If NOHZ is configured we allocate two 184 * wheels so we have a separate storage for the deferrable timers. 185 */ 186 #define WHEEL_SIZE (LVL_SIZE * LVL_DEPTH) 187 188 #ifdef CONFIG_NO_HZ_COMMON 189 # define NR_BASES 2 190 # define BASE_STD 0 191 # define BASE_DEF 1 192 #else 193 # define NR_BASES 1 194 # define BASE_STD 0 195 # define BASE_DEF 0 196 #endif 197 198 struct timer_base { 199 raw_spinlock_t lock; 200 struct timer_list *running_timer; 201 #ifdef CONFIG_PREEMPT_RT 202 spinlock_t expiry_lock; 203 atomic_t timer_waiters; 204 #endif 205 unsigned long clk; 206 unsigned long next_expiry; 207 unsigned int cpu; 208 bool next_expiry_recalc; 209 bool is_idle; 210 bool timers_pending; 211 DECLARE_BITMAP(pending_map, WHEEL_SIZE); 212 struct hlist_head vectors[WHEEL_SIZE]; 213 } ____cacheline_aligned; 214 215 static DEFINE_PER_CPU(struct timer_base, timer_bases[NR_BASES]); 216 217 #ifdef CONFIG_NO_HZ_COMMON 218 219 static DEFINE_STATIC_KEY_FALSE(timers_nohz_active); 220 static DEFINE_MUTEX(timer_keys_mutex); 221 222 static void timer_update_keys(struct work_struct *work); 223 static DECLARE_WORK(timer_update_work, timer_update_keys); 224 225 #ifdef CONFIG_SMP 226 unsigned int sysctl_timer_migration = 1; 227 228 DEFINE_STATIC_KEY_FALSE(timers_migration_enabled); 229 230 static void timers_update_migration(void) 231 { 232 if (sysctl_timer_migration && tick_nohz_active) 233 static_branch_enable(&timers_migration_enabled); 234 else 235 static_branch_disable(&timers_migration_enabled); 236 } 237 #else 238 static inline void timers_update_migration(void) { } 239 #endif /* !CONFIG_SMP */ 240 241 static void timer_update_keys(struct work_struct *work) 242 { 243 mutex_lock(&timer_keys_mutex); 244 timers_update_migration(); 245 static_branch_enable(&timers_nohz_active); 246 mutex_unlock(&timer_keys_mutex); 247 } 248 249 void timers_update_nohz(void) 250 { 251 schedule_work(&timer_update_work); 252 } 253 254 int timer_migration_handler(struct ctl_table *table, int write, 255 void *buffer, size_t *lenp, loff_t *ppos) 256 { 257 int ret; 258 259 mutex_lock(&timer_keys_mutex); 260 ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); 261 if (!ret && write) 262 timers_update_migration(); 263 mutex_unlock(&timer_keys_mutex); 264 return ret; 265 } 266 267 static inline bool is_timers_nohz_active(void) 268 { 269 return static_branch_unlikely(&timers_nohz_active); 270 } 271 #else 272 static inline bool is_timers_nohz_active(void) { return false; } 273 #endif /* NO_HZ_COMMON */ 274 275 static unsigned long round_jiffies_common(unsigned long j, int cpu, 276 bool force_up) 277 { 278 int rem; 279 unsigned long original = j; 280 281 /* 282 * We don't want all cpus firing their timers at once hitting the 283 * same lock or cachelines, so we skew each extra cpu with an extra 284 * 3 jiffies. This 3 jiffies came originally from the mm/ code which 285 * already did this. 286 * The skew is done by adding 3*cpunr, then round, then subtract this 287 * extra offset again. 288 */ 289 j += cpu * 3; 290 291 rem = j % HZ; 292 293 /* 294 * If the target jiffie is just after a whole second (which can happen 295 * due to delays of the timer irq, long irq off times etc etc) then 296 * we should round down to the whole second, not up. Use 1/4th second 297 * as cutoff for this rounding as an extreme upper bound for this. 298 * But never round down if @force_up is set. 299 */ 300 if (rem < HZ/4 && !force_up) /* round down */ 301 j = j - rem; 302 else /* round up */ 303 j = j - rem + HZ; 304 305 /* now that we have rounded, subtract the extra skew again */ 306 j -= cpu * 3; 307 308 /* 309 * Make sure j is still in the future. Otherwise return the 310 * unmodified value. 311 */ 312 return time_is_after_jiffies(j) ? j : original; 313 } 314 315 /** 316 * __round_jiffies - function to round jiffies to a full second 317 * @j: the time in (absolute) jiffies that should be rounded 318 * @cpu: the processor number on which the timeout will happen 319 * 320 * __round_jiffies() rounds an absolute time in the future (in jiffies) 321 * up or down to (approximately) full seconds. This is useful for timers 322 * for which the exact time they fire does not matter too much, as long as 323 * they fire approximately every X seconds. 324 * 325 * By rounding these timers to whole seconds, all such timers will fire 326 * at the same time, rather than at various times spread out. The goal 327 * of this is to have the CPU wake up less, which saves power. 328 * 329 * The exact rounding is skewed for each processor to avoid all 330 * processors firing at the exact same time, which could lead 331 * to lock contention or spurious cache line bouncing. 332 * 333 * The return value is the rounded version of the @j parameter. 334 */ 335 unsigned long __round_jiffies(unsigned long j, int cpu) 336 { 337 return round_jiffies_common(j, cpu, false); 338 } 339 EXPORT_SYMBOL_GPL(__round_jiffies); 340 341 /** 342 * __round_jiffies_relative - function to round jiffies to a full second 343 * @j: the time in (relative) jiffies that should be rounded 344 * @cpu: the processor number on which the timeout will happen 345 * 346 * __round_jiffies_relative() rounds a time delta in the future (in jiffies) 347 * up or down to (approximately) full seconds. This is useful for timers 348 * for which the exact time they fire does not matter too much, as long as 349 * they fire approximately every X seconds. 350 * 351 * By rounding these timers to whole seconds, all such timers will fire 352 * at the same time, rather than at various times spread out. The goal 353 * of this is to have the CPU wake up less, which saves power. 354 * 355 * The exact rounding is skewed for each processor to avoid all 356 * processors firing at the exact same time, which could lead 357 * to lock contention or spurious cache line bouncing. 358 * 359 * The return value is the rounded version of the @j parameter. 360 */ 361 unsigned long __round_jiffies_relative(unsigned long j, int cpu) 362 { 363 unsigned long j0 = jiffies; 364 365 /* Use j0 because jiffies might change while we run */ 366 return round_jiffies_common(j + j0, cpu, false) - j0; 367 } 368 EXPORT_SYMBOL_GPL(__round_jiffies_relative); 369 370 /** 371 * round_jiffies - function to round jiffies to a full second 372 * @j: the time in (absolute) jiffies that should be rounded 373 * 374 * round_jiffies() rounds an absolute time in the future (in jiffies) 375 * up or down to (approximately) full seconds. This is useful for timers 376 * for which the exact time they fire does not matter too much, as long as 377 * they fire approximately every X seconds. 378 * 379 * By rounding these timers to whole seconds, all such timers will fire 380 * at the same time, rather than at various times spread out. The goal 381 * of this is to have the CPU wake up less, which saves power. 382 * 383 * The return value is the rounded version of the @j parameter. 384 */ 385 unsigned long round_jiffies(unsigned long j) 386 { 387 return round_jiffies_common(j, raw_smp_processor_id(), false); 388 } 389 EXPORT_SYMBOL_GPL(round_jiffies); 390 391 /** 392 * round_jiffies_relative - function to round jiffies to a full second 393 * @j: the time in (relative) jiffies that should be rounded 394 * 395 * round_jiffies_relative() rounds a time delta in the future (in jiffies) 396 * up or down to (approximately) full seconds. This is useful for timers 397 * for which the exact time they fire does not matter too much, as long as 398 * they fire approximately every X seconds. 399 * 400 * By rounding these timers to whole seconds, all such timers will fire 401 * at the same time, rather than at various times spread out. The goal 402 * of this is to have the CPU wake up less, which saves power. 403 * 404 * The return value is the rounded version of the @j parameter. 405 */ 406 unsigned long round_jiffies_relative(unsigned long j) 407 { 408 return __round_jiffies_relative(j, raw_smp_processor_id()); 409 } 410 EXPORT_SYMBOL_GPL(round_jiffies_relative); 411 412 /** 413 * __round_jiffies_up - function to round jiffies up to a full second 414 * @j: the time in (absolute) jiffies that should be rounded 415 * @cpu: the processor number on which the timeout will happen 416 * 417 * This is the same as __round_jiffies() except that it will never 418 * round down. This is useful for timeouts for which the exact time 419 * of firing does not matter too much, as long as they don't fire too 420 * early. 421 */ 422 unsigned long __round_jiffies_up(unsigned long j, int cpu) 423 { 424 return round_jiffies_common(j, cpu, true); 425 } 426 EXPORT_SYMBOL_GPL(__round_jiffies_up); 427 428 /** 429 * __round_jiffies_up_relative - function to round jiffies up to a full second 430 * @j: the time in (relative) jiffies that should be rounded 431 * @cpu: the processor number on which the timeout will happen 432 * 433 * This is the same as __round_jiffies_relative() except that it will never 434 * round down. This is useful for timeouts for which the exact time 435 * of firing does not matter too much, as long as they don't fire too 436 * early. 437 */ 438 unsigned long __round_jiffies_up_relative(unsigned long j, int cpu) 439 { 440 unsigned long j0 = jiffies; 441 442 /* Use j0 because jiffies might change while we run */ 443 return round_jiffies_common(j + j0, cpu, true) - j0; 444 } 445 EXPORT_SYMBOL_GPL(__round_jiffies_up_relative); 446 447 /** 448 * round_jiffies_up - function to round jiffies up to a full second 449 * @j: the time in (absolute) jiffies that should be rounded 450 * 451 * This is the same as round_jiffies() except that it will never 452 * round down. This is useful for timeouts for which the exact time 453 * of firing does not matter too much, as long as they don't fire too 454 * early. 455 */ 456 unsigned long round_jiffies_up(unsigned long j) 457 { 458 return round_jiffies_common(j, raw_smp_processor_id(), true); 459 } 460 EXPORT_SYMBOL_GPL(round_jiffies_up); 461 462 /** 463 * round_jiffies_up_relative - function to round jiffies up to a full second 464 * @j: the time in (relative) jiffies that should be rounded 465 * 466 * This is the same as round_jiffies_relative() except that it will never 467 * round down. This is useful for timeouts for which the exact time 468 * of firing does not matter too much, as long as they don't fire too 469 * early. 470 */ 471 unsigned long round_jiffies_up_relative(unsigned long j) 472 { 473 return __round_jiffies_up_relative(j, raw_smp_processor_id()); 474 } 475 EXPORT_SYMBOL_GPL(round_jiffies_up_relative); 476 477 478 static inline unsigned int timer_get_idx(struct timer_list *timer) 479 { 480 return (timer->flags & TIMER_ARRAYMASK) >> TIMER_ARRAYSHIFT; 481 } 482 483 static inline void timer_set_idx(struct timer_list *timer, unsigned int idx) 484 { 485 timer->flags = (timer->flags & ~TIMER_ARRAYMASK) | 486 idx << TIMER_ARRAYSHIFT; 487 } 488 489 /* 490 * Helper function to calculate the array index for a given expiry 491 * time. 492 */ 493 static inline unsigned calc_index(unsigned long expires, unsigned lvl, 494 unsigned long *bucket_expiry) 495 { 496 497 /* 498 * The timer wheel has to guarantee that a timer does not fire 499 * early. Early expiry can happen due to: 500 * - Timer is armed at the edge of a tick 501 * - Truncation of the expiry time in the outer wheel levels 502 * 503 * Round up with level granularity to prevent this. 504 */ 505 expires = (expires + LVL_GRAN(lvl)) >> LVL_SHIFT(lvl); 506 *bucket_expiry = expires << LVL_SHIFT(lvl); 507 return LVL_OFFS(lvl) + (expires & LVL_MASK); 508 } 509 510 static int calc_wheel_index(unsigned long expires, unsigned long clk, 511 unsigned long *bucket_expiry) 512 { 513 unsigned long delta = expires - clk; 514 unsigned int idx; 515 516 if (delta < LVL_START(1)) { 517 idx = calc_index(expires, 0, bucket_expiry); 518 } else if (delta < LVL_START(2)) { 519 idx = calc_index(expires, 1, bucket_expiry); 520 } else if (delta < LVL_START(3)) { 521 idx = calc_index(expires, 2, bucket_expiry); 522 } else if (delta < LVL_START(4)) { 523 idx = calc_index(expires, 3, bucket_expiry); 524 } else if (delta < LVL_START(5)) { 525 idx = calc_index(expires, 4, bucket_expiry); 526 } else if (delta < LVL_START(6)) { 527 idx = calc_index(expires, 5, bucket_expiry); 528 } else if (delta < LVL_START(7)) { 529 idx = calc_index(expires, 6, bucket_expiry); 530 } else if (LVL_DEPTH > 8 && delta < LVL_START(8)) { 531 idx = calc_index(expires, 7, bucket_expiry); 532 } else if ((long) delta < 0) { 533 idx = clk & LVL_MASK; 534 *bucket_expiry = clk; 535 } else { 536 /* 537 * Force expire obscene large timeouts to expire at the 538 * capacity limit of the wheel. 539 */ 540 if (delta >= WHEEL_TIMEOUT_CUTOFF) 541 expires = clk + WHEEL_TIMEOUT_MAX; 542 543 idx = calc_index(expires, LVL_DEPTH - 1, bucket_expiry); 544 } 545 return idx; 546 } 547 548 static void 549 trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer) 550 { 551 if (!is_timers_nohz_active()) 552 return; 553 554 /* 555 * TODO: This wants some optimizing similar to the code below, but we 556 * will do that when we switch from push to pull for deferrable timers. 557 */ 558 if (timer->flags & TIMER_DEFERRABLE) { 559 if (tick_nohz_full_cpu(base->cpu)) 560 wake_up_nohz_cpu(base->cpu); 561 return; 562 } 563 564 /* 565 * We might have to IPI the remote CPU if the base is idle and the 566 * timer is not deferrable. If the other CPU is on the way to idle 567 * then it can't set base->is_idle as we hold the base lock: 568 */ 569 if (base->is_idle) 570 wake_up_nohz_cpu(base->cpu); 571 } 572 573 /* 574 * Enqueue the timer into the hash bucket, mark it pending in 575 * the bitmap, store the index in the timer flags then wake up 576 * the target CPU if needed. 577 */ 578 static void enqueue_timer(struct timer_base *base, struct timer_list *timer, 579 unsigned int idx, unsigned long bucket_expiry) 580 { 581 582 hlist_add_head(&timer->entry, base->vectors + idx); 583 __set_bit(idx, base->pending_map); 584 timer_set_idx(timer, idx); 585 586 trace_timer_start(timer, timer->expires, timer->flags); 587 588 /* 589 * Check whether this is the new first expiring timer. The 590 * effective expiry time of the timer is required here 591 * (bucket_expiry) instead of timer->expires. 592 */ 593 if (time_before(bucket_expiry, base->next_expiry)) { 594 /* 595 * Set the next expiry time and kick the CPU so it 596 * can reevaluate the wheel: 597 */ 598 base->next_expiry = bucket_expiry; 599 base->timers_pending = true; 600 base->next_expiry_recalc = false; 601 trigger_dyntick_cpu(base, timer); 602 } 603 } 604 605 static void internal_add_timer(struct timer_base *base, struct timer_list *timer) 606 { 607 unsigned long bucket_expiry; 608 unsigned int idx; 609 610 idx = calc_wheel_index(timer->expires, base->clk, &bucket_expiry); 611 enqueue_timer(base, timer, idx, bucket_expiry); 612 } 613 614 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS 615 616 static const struct debug_obj_descr timer_debug_descr; 617 618 static void *timer_debug_hint(void *addr) 619 { 620 return ((struct timer_list *) addr)->function; 621 } 622 623 static bool timer_is_static_object(void *addr) 624 { 625 struct timer_list *timer = addr; 626 627 return (timer->entry.pprev == NULL && 628 timer->entry.next == TIMER_ENTRY_STATIC); 629 } 630 631 /* 632 * fixup_init is called when: 633 * - an active object is initialized 634 */ 635 static bool timer_fixup_init(void *addr, enum debug_obj_state state) 636 { 637 struct timer_list *timer = addr; 638 639 switch (state) { 640 case ODEBUG_STATE_ACTIVE: 641 del_timer_sync(timer); 642 debug_object_init(timer, &timer_debug_descr); 643 return true; 644 default: 645 return false; 646 } 647 } 648 649 /* Stub timer callback for improperly used timers. */ 650 static void stub_timer(struct timer_list *unused) 651 { 652 WARN_ON(1); 653 } 654 655 /* 656 * fixup_activate is called when: 657 * - an active object is activated 658 * - an unknown non-static object is activated 659 */ 660 static bool timer_fixup_activate(void *addr, enum debug_obj_state state) 661 { 662 struct timer_list *timer = addr; 663 664 switch (state) { 665 case ODEBUG_STATE_NOTAVAILABLE: 666 timer_setup(timer, stub_timer, 0); 667 return true; 668 669 case ODEBUG_STATE_ACTIVE: 670 WARN_ON(1); 671 fallthrough; 672 default: 673 return false; 674 } 675 } 676 677 /* 678 * fixup_free is called when: 679 * - an active object is freed 680 */ 681 static bool timer_fixup_free(void *addr, enum debug_obj_state state) 682 { 683 struct timer_list *timer = addr; 684 685 switch (state) { 686 case ODEBUG_STATE_ACTIVE: 687 del_timer_sync(timer); 688 debug_object_free(timer, &timer_debug_descr); 689 return true; 690 default: 691 return false; 692 } 693 } 694 695 /* 696 * fixup_assert_init is called when: 697 * - an untracked/uninit-ed object is found 698 */ 699 static bool timer_fixup_assert_init(void *addr, enum debug_obj_state state) 700 { 701 struct timer_list *timer = addr; 702 703 switch (state) { 704 case ODEBUG_STATE_NOTAVAILABLE: 705 timer_setup(timer, stub_timer, 0); 706 return true; 707 default: 708 return false; 709 } 710 } 711 712 static const struct debug_obj_descr timer_debug_descr = { 713 .name = "timer_list", 714 .debug_hint = timer_debug_hint, 715 .is_static_object = timer_is_static_object, 716 .fixup_init = timer_fixup_init, 717 .fixup_activate = timer_fixup_activate, 718 .fixup_free = timer_fixup_free, 719 .fixup_assert_init = timer_fixup_assert_init, 720 }; 721 722 static inline void debug_timer_init(struct timer_list *timer) 723 { 724 debug_object_init(timer, &timer_debug_descr); 725 } 726 727 static inline void debug_timer_activate(struct timer_list *timer) 728 { 729 debug_object_activate(timer, &timer_debug_descr); 730 } 731 732 static inline void debug_timer_deactivate(struct timer_list *timer) 733 { 734 debug_object_deactivate(timer, &timer_debug_descr); 735 } 736 737 static inline void debug_timer_assert_init(struct timer_list *timer) 738 { 739 debug_object_assert_init(timer, &timer_debug_descr); 740 } 741 742 static void do_init_timer(struct timer_list *timer, 743 void (*func)(struct timer_list *), 744 unsigned int flags, 745 const char *name, struct lock_class_key *key); 746 747 void init_timer_on_stack_key(struct timer_list *timer, 748 void (*func)(struct timer_list *), 749 unsigned int flags, 750 const char *name, struct lock_class_key *key) 751 { 752 debug_object_init_on_stack(timer, &timer_debug_descr); 753 do_init_timer(timer, func, flags, name, key); 754 } 755 EXPORT_SYMBOL_GPL(init_timer_on_stack_key); 756 757 void destroy_timer_on_stack(struct timer_list *timer) 758 { 759 debug_object_free(timer, &timer_debug_descr); 760 } 761 EXPORT_SYMBOL_GPL(destroy_timer_on_stack); 762 763 #else 764 static inline void debug_timer_init(struct timer_list *timer) { } 765 static inline void debug_timer_activate(struct timer_list *timer) { } 766 static inline void debug_timer_deactivate(struct timer_list *timer) { } 767 static inline void debug_timer_assert_init(struct timer_list *timer) { } 768 #endif 769 770 static inline void debug_init(struct timer_list *timer) 771 { 772 debug_timer_init(timer); 773 trace_timer_init(timer); 774 } 775 776 static inline void debug_deactivate(struct timer_list *timer) 777 { 778 debug_timer_deactivate(timer); 779 trace_timer_cancel(timer); 780 } 781 782 static inline void debug_assert_init(struct timer_list *timer) 783 { 784 debug_timer_assert_init(timer); 785 } 786 787 static void do_init_timer(struct timer_list *timer, 788 void (*func)(struct timer_list *), 789 unsigned int flags, 790 const char *name, struct lock_class_key *key) 791 { 792 timer->entry.pprev = NULL; 793 timer->function = func; 794 if (WARN_ON_ONCE(flags & ~TIMER_INIT_FLAGS)) 795 flags &= TIMER_INIT_FLAGS; 796 timer->flags = flags | raw_smp_processor_id(); 797 lockdep_init_map(&timer->lockdep_map, name, key, 0); 798 } 799 800 /** 801 * init_timer_key - initialize a timer 802 * @timer: the timer to be initialized 803 * @func: timer callback function 804 * @flags: timer flags 805 * @name: name of the timer 806 * @key: lockdep class key of the fake lock used for tracking timer 807 * sync lock dependencies 808 * 809 * init_timer_key() must be done to a timer prior calling *any* of the 810 * other timer functions. 811 */ 812 void init_timer_key(struct timer_list *timer, 813 void (*func)(struct timer_list *), unsigned int flags, 814 const char *name, struct lock_class_key *key) 815 { 816 debug_init(timer); 817 do_init_timer(timer, func, flags, name, key); 818 } 819 EXPORT_SYMBOL(init_timer_key); 820 821 static inline void detach_timer(struct timer_list *timer, bool clear_pending) 822 { 823 struct hlist_node *entry = &timer->entry; 824 825 debug_deactivate(timer); 826 827 __hlist_del(entry); 828 if (clear_pending) 829 entry->pprev = NULL; 830 entry->next = LIST_POISON2; 831 } 832 833 static int detach_if_pending(struct timer_list *timer, struct timer_base *base, 834 bool clear_pending) 835 { 836 unsigned idx = timer_get_idx(timer); 837 838 if (!timer_pending(timer)) 839 return 0; 840 841 if (hlist_is_singular_node(&timer->entry, base->vectors + idx)) { 842 __clear_bit(idx, base->pending_map); 843 base->next_expiry_recalc = true; 844 } 845 846 detach_timer(timer, clear_pending); 847 return 1; 848 } 849 850 static inline struct timer_base *get_timer_cpu_base(u32 tflags, u32 cpu) 851 { 852 struct timer_base *base = per_cpu_ptr(&timer_bases[BASE_STD], cpu); 853 854 /* 855 * If the timer is deferrable and NO_HZ_COMMON is set then we need 856 * to use the deferrable base. 857 */ 858 if (IS_ENABLED(CONFIG_NO_HZ_COMMON) && (tflags & TIMER_DEFERRABLE)) 859 base = per_cpu_ptr(&timer_bases[BASE_DEF], cpu); 860 return base; 861 } 862 863 static inline struct timer_base *get_timer_this_cpu_base(u32 tflags) 864 { 865 struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]); 866 867 /* 868 * If the timer is deferrable and NO_HZ_COMMON is set then we need 869 * to use the deferrable base. 870 */ 871 if (IS_ENABLED(CONFIG_NO_HZ_COMMON) && (tflags & TIMER_DEFERRABLE)) 872 base = this_cpu_ptr(&timer_bases[BASE_DEF]); 873 return base; 874 } 875 876 static inline struct timer_base *get_timer_base(u32 tflags) 877 { 878 return get_timer_cpu_base(tflags, tflags & TIMER_CPUMASK); 879 } 880 881 static inline struct timer_base * 882 get_target_base(struct timer_base *base, unsigned tflags) 883 { 884 #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON) 885 if (static_branch_likely(&timers_migration_enabled) && 886 !(tflags & TIMER_PINNED)) 887 return get_timer_cpu_base(tflags, get_nohz_timer_target()); 888 #endif 889 return get_timer_this_cpu_base(tflags); 890 } 891 892 static inline void forward_timer_base(struct timer_base *base) 893 { 894 unsigned long jnow = READ_ONCE(jiffies); 895 896 /* 897 * No need to forward if we are close enough below jiffies. 898 * Also while executing timers, base->clk is 1 offset ahead 899 * of jiffies to avoid endless requeuing to current jiffies. 900 */ 901 if ((long)(jnow - base->clk) < 1) 902 return; 903 904 /* 905 * If the next expiry value is > jiffies, then we fast forward to 906 * jiffies otherwise we forward to the next expiry value. 907 */ 908 if (time_after(base->next_expiry, jnow)) { 909 base->clk = jnow; 910 } else { 911 if (WARN_ON_ONCE(time_before(base->next_expiry, base->clk))) 912 return; 913 base->clk = base->next_expiry; 914 } 915 } 916 917 918 /* 919 * We are using hashed locking: Holding per_cpu(timer_bases[x]).lock means 920 * that all timers which are tied to this base are locked, and the base itself 921 * is locked too. 922 * 923 * So __run_timers/migrate_timers can safely modify all timers which could 924 * be found in the base->vectors array. 925 * 926 * When a timer is migrating then the TIMER_MIGRATING flag is set and we need 927 * to wait until the migration is done. 928 */ 929 static struct timer_base *lock_timer_base(struct timer_list *timer, 930 unsigned long *flags) 931 __acquires(timer->base->lock) 932 { 933 for (;;) { 934 struct timer_base *base; 935 u32 tf; 936 937 /* 938 * We need to use READ_ONCE() here, otherwise the compiler 939 * might re-read @tf between the check for TIMER_MIGRATING 940 * and spin_lock(). 941 */ 942 tf = READ_ONCE(timer->flags); 943 944 if (!(tf & TIMER_MIGRATING)) { 945 base = get_timer_base(tf); 946 raw_spin_lock_irqsave(&base->lock, *flags); 947 if (timer->flags == tf) 948 return base; 949 raw_spin_unlock_irqrestore(&base->lock, *flags); 950 } 951 cpu_relax(); 952 } 953 } 954 955 #define MOD_TIMER_PENDING_ONLY 0x01 956 #define MOD_TIMER_REDUCE 0x02 957 #define MOD_TIMER_NOTPENDING 0x04 958 959 static inline int 960 __mod_timer(struct timer_list *timer, unsigned long expires, unsigned int options) 961 { 962 unsigned long clk = 0, flags, bucket_expiry; 963 struct timer_base *base, *new_base; 964 unsigned int idx = UINT_MAX; 965 int ret = 0; 966 967 BUG_ON(!timer->function); 968 969 /* 970 * This is a common optimization triggered by the networking code - if 971 * the timer is re-modified to have the same timeout or ends up in the 972 * same array bucket then just return: 973 */ 974 if (!(options & MOD_TIMER_NOTPENDING) && timer_pending(timer)) { 975 /* 976 * The downside of this optimization is that it can result in 977 * larger granularity than you would get from adding a new 978 * timer with this expiry. 979 */ 980 long diff = timer->expires - expires; 981 982 if (!diff) 983 return 1; 984 if (options & MOD_TIMER_REDUCE && diff <= 0) 985 return 1; 986 987 /* 988 * We lock timer base and calculate the bucket index right 989 * here. If the timer ends up in the same bucket, then we 990 * just update the expiry time and avoid the whole 991 * dequeue/enqueue dance. 992 */ 993 base = lock_timer_base(timer, &flags); 994 forward_timer_base(base); 995 996 if (timer_pending(timer) && (options & MOD_TIMER_REDUCE) && 997 time_before_eq(timer->expires, expires)) { 998 ret = 1; 999 goto out_unlock; 1000 } 1001 1002 clk = base->clk; 1003 idx = calc_wheel_index(expires, clk, &bucket_expiry); 1004 1005 /* 1006 * Retrieve and compare the array index of the pending 1007 * timer. If it matches set the expiry to the new value so a 1008 * subsequent call will exit in the expires check above. 1009 */ 1010 if (idx == timer_get_idx(timer)) { 1011 if (!(options & MOD_TIMER_REDUCE)) 1012 timer->expires = expires; 1013 else if (time_after(timer->expires, expires)) 1014 timer->expires = expires; 1015 ret = 1; 1016 goto out_unlock; 1017 } 1018 } else { 1019 base = lock_timer_base(timer, &flags); 1020 forward_timer_base(base); 1021 } 1022 1023 ret = detach_if_pending(timer, base, false); 1024 if (!ret && (options & MOD_TIMER_PENDING_ONLY)) 1025 goto out_unlock; 1026 1027 new_base = get_target_base(base, timer->flags); 1028 1029 if (base != new_base) { 1030 /* 1031 * We are trying to schedule the timer on the new base. 1032 * However we can't change timer's base while it is running, 1033 * otherwise del_timer_sync() can't detect that the timer's 1034 * handler yet has not finished. This also guarantees that the 1035 * timer is serialized wrt itself. 1036 */ 1037 if (likely(base->running_timer != timer)) { 1038 /* See the comment in lock_timer_base() */ 1039 timer->flags |= TIMER_MIGRATING; 1040 1041 raw_spin_unlock(&base->lock); 1042 base = new_base; 1043 raw_spin_lock(&base->lock); 1044 WRITE_ONCE(timer->flags, 1045 (timer->flags & ~TIMER_BASEMASK) | base->cpu); 1046 forward_timer_base(base); 1047 } 1048 } 1049 1050 debug_timer_activate(timer); 1051 1052 timer->expires = expires; 1053 /* 1054 * If 'idx' was calculated above and the base time did not advance 1055 * between calculating 'idx' and possibly switching the base, only 1056 * enqueue_timer() is required. Otherwise we need to (re)calculate 1057 * the wheel index via internal_add_timer(). 1058 */ 1059 if (idx != UINT_MAX && clk == base->clk) 1060 enqueue_timer(base, timer, idx, bucket_expiry); 1061 else 1062 internal_add_timer(base, timer); 1063 1064 out_unlock: 1065 raw_spin_unlock_irqrestore(&base->lock, flags); 1066 1067 return ret; 1068 } 1069 1070 /** 1071 * mod_timer_pending - modify a pending timer's timeout 1072 * @timer: the pending timer to be modified 1073 * @expires: new timeout in jiffies 1074 * 1075 * mod_timer_pending() is the same for pending timers as mod_timer(), 1076 * but will not re-activate and modify already deleted timers. 1077 * 1078 * It is useful for unserialized use of timers. 1079 */ 1080 int mod_timer_pending(struct timer_list *timer, unsigned long expires) 1081 { 1082 return __mod_timer(timer, expires, MOD_TIMER_PENDING_ONLY); 1083 } 1084 EXPORT_SYMBOL(mod_timer_pending); 1085 1086 /** 1087 * mod_timer - modify a timer's timeout 1088 * @timer: the timer to be modified 1089 * @expires: new timeout in jiffies 1090 * 1091 * mod_timer() is a more efficient way to update the expire field of an 1092 * active timer (if the timer is inactive it will be activated) 1093 * 1094 * mod_timer(timer, expires) is equivalent to: 1095 * 1096 * del_timer(timer); timer->expires = expires; add_timer(timer); 1097 * 1098 * Note that if there are multiple unserialized concurrent users of the 1099 * same timer, then mod_timer() is the only safe way to modify the timeout, 1100 * since add_timer() cannot modify an already running timer. 1101 * 1102 * The function returns whether it has modified a pending timer or not. 1103 * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an 1104 * active timer returns 1.) 1105 */ 1106 int mod_timer(struct timer_list *timer, unsigned long expires) 1107 { 1108 return __mod_timer(timer, expires, 0); 1109 } 1110 EXPORT_SYMBOL(mod_timer); 1111 1112 /** 1113 * timer_reduce - Modify a timer's timeout if it would reduce the timeout 1114 * @timer: The timer to be modified 1115 * @expires: New timeout in jiffies 1116 * 1117 * timer_reduce() is very similar to mod_timer(), except that it will only 1118 * modify a running timer if that would reduce the expiration time (it will 1119 * start a timer that isn't running). 1120 */ 1121 int timer_reduce(struct timer_list *timer, unsigned long expires) 1122 { 1123 return __mod_timer(timer, expires, MOD_TIMER_REDUCE); 1124 } 1125 EXPORT_SYMBOL(timer_reduce); 1126 1127 /** 1128 * add_timer - start a timer 1129 * @timer: the timer to be added 1130 * 1131 * The kernel will do a ->function(@timer) callback from the 1132 * timer interrupt at the ->expires point in the future. The 1133 * current time is 'jiffies'. 1134 * 1135 * The timer's ->expires, ->function fields must be set prior calling this 1136 * function. 1137 * 1138 * Timers with an ->expires field in the past will be executed in the next 1139 * timer tick. 1140 */ 1141 void add_timer(struct timer_list *timer) 1142 { 1143 BUG_ON(timer_pending(timer)); 1144 __mod_timer(timer, timer->expires, MOD_TIMER_NOTPENDING); 1145 } 1146 EXPORT_SYMBOL(add_timer); 1147 1148 /** 1149 * add_timer_on - start a timer on a particular CPU 1150 * @timer: the timer to be added 1151 * @cpu: the CPU to start it on 1152 * 1153 * This is not very scalable on SMP. Double adds are not possible. 1154 */ 1155 void add_timer_on(struct timer_list *timer, int cpu) 1156 { 1157 struct timer_base *new_base, *base; 1158 unsigned long flags; 1159 1160 BUG_ON(timer_pending(timer) || !timer->function); 1161 1162 new_base = get_timer_cpu_base(timer->flags, cpu); 1163 1164 /* 1165 * If @timer was on a different CPU, it should be migrated with the 1166 * old base locked to prevent other operations proceeding with the 1167 * wrong base locked. See lock_timer_base(). 1168 */ 1169 base = lock_timer_base(timer, &flags); 1170 if (base != new_base) { 1171 timer->flags |= TIMER_MIGRATING; 1172 1173 raw_spin_unlock(&base->lock); 1174 base = new_base; 1175 raw_spin_lock(&base->lock); 1176 WRITE_ONCE(timer->flags, 1177 (timer->flags & ~TIMER_BASEMASK) | cpu); 1178 } 1179 forward_timer_base(base); 1180 1181 debug_timer_activate(timer); 1182 internal_add_timer(base, timer); 1183 raw_spin_unlock_irqrestore(&base->lock, flags); 1184 } 1185 EXPORT_SYMBOL_GPL(add_timer_on); 1186 1187 /** 1188 * del_timer - deactivate a timer. 1189 * @timer: the timer to be deactivated 1190 * 1191 * del_timer() deactivates a timer - this works on both active and inactive 1192 * timers. 1193 * 1194 * The function returns whether it has deactivated a pending timer or not. 1195 * (ie. del_timer() of an inactive timer returns 0, del_timer() of an 1196 * active timer returns 1.) 1197 */ 1198 int del_timer(struct timer_list *timer) 1199 { 1200 struct timer_base *base; 1201 unsigned long flags; 1202 int ret = 0; 1203 1204 debug_assert_init(timer); 1205 1206 if (timer_pending(timer)) { 1207 base = lock_timer_base(timer, &flags); 1208 ret = detach_if_pending(timer, base, true); 1209 raw_spin_unlock_irqrestore(&base->lock, flags); 1210 } 1211 1212 return ret; 1213 } 1214 EXPORT_SYMBOL(del_timer); 1215 1216 /** 1217 * try_to_del_timer_sync - Try to deactivate a timer 1218 * @timer: timer to delete 1219 * 1220 * This function tries to deactivate a timer. Upon successful (ret >= 0) 1221 * exit the timer is not queued and the handler is not running on any CPU. 1222 */ 1223 int try_to_del_timer_sync(struct timer_list *timer) 1224 { 1225 struct timer_base *base; 1226 unsigned long flags; 1227 int ret = -1; 1228 1229 debug_assert_init(timer); 1230 1231 base = lock_timer_base(timer, &flags); 1232 1233 if (base->running_timer != timer) 1234 ret = detach_if_pending(timer, base, true); 1235 1236 raw_spin_unlock_irqrestore(&base->lock, flags); 1237 1238 return ret; 1239 } 1240 EXPORT_SYMBOL(try_to_del_timer_sync); 1241 1242 #ifdef CONFIG_PREEMPT_RT 1243 static __init void timer_base_init_expiry_lock(struct timer_base *base) 1244 { 1245 spin_lock_init(&base->expiry_lock); 1246 } 1247 1248 static inline void timer_base_lock_expiry(struct timer_base *base) 1249 { 1250 spin_lock(&base->expiry_lock); 1251 } 1252 1253 static inline void timer_base_unlock_expiry(struct timer_base *base) 1254 { 1255 spin_unlock(&base->expiry_lock); 1256 } 1257 1258 /* 1259 * The counterpart to del_timer_wait_running(). 1260 * 1261 * If there is a waiter for base->expiry_lock, then it was waiting for the 1262 * timer callback to finish. Drop expiry_lock and reacquire it. That allows 1263 * the waiter to acquire the lock and make progress. 1264 */ 1265 static void timer_sync_wait_running(struct timer_base *base) 1266 { 1267 if (atomic_read(&base->timer_waiters)) { 1268 raw_spin_unlock_irq(&base->lock); 1269 spin_unlock(&base->expiry_lock); 1270 spin_lock(&base->expiry_lock); 1271 raw_spin_lock_irq(&base->lock); 1272 } 1273 } 1274 1275 /* 1276 * This function is called on PREEMPT_RT kernels when the fast path 1277 * deletion of a timer failed because the timer callback function was 1278 * running. 1279 * 1280 * This prevents priority inversion, if the softirq thread on a remote CPU 1281 * got preempted, and it prevents a life lock when the task which tries to 1282 * delete a timer preempted the softirq thread running the timer callback 1283 * function. 1284 */ 1285 static void del_timer_wait_running(struct timer_list *timer) 1286 { 1287 u32 tf; 1288 1289 tf = READ_ONCE(timer->flags); 1290 if (!(tf & (TIMER_MIGRATING | TIMER_IRQSAFE))) { 1291 struct timer_base *base = get_timer_base(tf); 1292 1293 /* 1294 * Mark the base as contended and grab the expiry lock, 1295 * which is held by the softirq across the timer 1296 * callback. Drop the lock immediately so the softirq can 1297 * expire the next timer. In theory the timer could already 1298 * be running again, but that's more than unlikely and just 1299 * causes another wait loop. 1300 */ 1301 atomic_inc(&base->timer_waiters); 1302 spin_lock_bh(&base->expiry_lock); 1303 atomic_dec(&base->timer_waiters); 1304 spin_unlock_bh(&base->expiry_lock); 1305 } 1306 } 1307 #else 1308 static inline void timer_base_init_expiry_lock(struct timer_base *base) { } 1309 static inline void timer_base_lock_expiry(struct timer_base *base) { } 1310 static inline void timer_base_unlock_expiry(struct timer_base *base) { } 1311 static inline void timer_sync_wait_running(struct timer_base *base) { } 1312 static inline void del_timer_wait_running(struct timer_list *timer) { } 1313 #endif 1314 1315 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT) 1316 /** 1317 * del_timer_sync - deactivate a timer and wait for the handler to finish. 1318 * @timer: the timer to be deactivated 1319 * 1320 * This function only differs from del_timer() on SMP: besides deactivating 1321 * the timer it also makes sure the handler has finished executing on other 1322 * CPUs. 1323 * 1324 * Synchronization rules: Callers must prevent restarting of the timer, 1325 * otherwise this function is meaningless. It must not be called from 1326 * interrupt contexts unless the timer is an irqsafe one. The caller must 1327 * not hold locks which would prevent completion of the timer's 1328 * handler. The timer's handler must not call add_timer_on(). Upon exit the 1329 * timer is not queued and the handler is not running on any CPU. 1330 * 1331 * Note: For !irqsafe timers, you must not hold locks that are held in 1332 * interrupt context while calling this function. Even if the lock has 1333 * nothing to do with the timer in question. Here's why:: 1334 * 1335 * CPU0 CPU1 1336 * ---- ---- 1337 * <SOFTIRQ> 1338 * call_timer_fn(); 1339 * base->running_timer = mytimer; 1340 * spin_lock_irq(somelock); 1341 * <IRQ> 1342 * spin_lock(somelock); 1343 * del_timer_sync(mytimer); 1344 * while (base->running_timer == mytimer); 1345 * 1346 * Now del_timer_sync() will never return and never release somelock. 1347 * The interrupt on the other CPU is waiting to grab somelock but 1348 * it has interrupted the softirq that CPU0 is waiting to finish. 1349 * 1350 * The function returns whether it has deactivated a pending timer or not. 1351 */ 1352 int del_timer_sync(struct timer_list *timer) 1353 { 1354 int ret; 1355 1356 #ifdef CONFIG_LOCKDEP 1357 unsigned long flags; 1358 1359 /* 1360 * If lockdep gives a backtrace here, please reference 1361 * the synchronization rules above. 1362 */ 1363 local_irq_save(flags); 1364 lock_map_acquire(&timer->lockdep_map); 1365 lock_map_release(&timer->lockdep_map); 1366 local_irq_restore(flags); 1367 #endif 1368 /* 1369 * don't use it in hardirq context, because it 1370 * could lead to deadlock. 1371 */ 1372 WARN_ON(in_irq() && !(timer->flags & TIMER_IRQSAFE)); 1373 1374 /* 1375 * Must be able to sleep on PREEMPT_RT because of the slowpath in 1376 * del_timer_wait_running(). 1377 */ 1378 if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(timer->flags & TIMER_IRQSAFE)) 1379 lockdep_assert_preemption_enabled(); 1380 1381 do { 1382 ret = try_to_del_timer_sync(timer); 1383 1384 if (unlikely(ret < 0)) { 1385 del_timer_wait_running(timer); 1386 cpu_relax(); 1387 } 1388 } while (ret < 0); 1389 1390 return ret; 1391 } 1392 EXPORT_SYMBOL(del_timer_sync); 1393 #endif 1394 1395 static void call_timer_fn(struct timer_list *timer, 1396 void (*fn)(struct timer_list *), 1397 unsigned long baseclk) 1398 { 1399 int count = preempt_count(); 1400 1401 #ifdef CONFIG_LOCKDEP 1402 /* 1403 * It is permissible to free the timer from inside the 1404 * function that is called from it, this we need to take into 1405 * account for lockdep too. To avoid bogus "held lock freed" 1406 * warnings as well as problems when looking into 1407 * timer->lockdep_map, make a copy and use that here. 1408 */ 1409 struct lockdep_map lockdep_map; 1410 1411 lockdep_copy_map(&lockdep_map, &timer->lockdep_map); 1412 #endif 1413 /* 1414 * Couple the lock chain with the lock chain at 1415 * del_timer_sync() by acquiring the lock_map around the fn() 1416 * call here and in del_timer_sync(). 1417 */ 1418 lock_map_acquire(&lockdep_map); 1419 1420 trace_timer_expire_entry(timer, baseclk); 1421 fn(timer); 1422 trace_timer_expire_exit(timer); 1423 1424 lock_map_release(&lockdep_map); 1425 1426 if (count != preempt_count()) { 1427 WARN_ONCE(1, "timer: %pS preempt leak: %08x -> %08x\n", 1428 fn, count, preempt_count()); 1429 /* 1430 * Restore the preempt count. That gives us a decent 1431 * chance to survive and extract information. If the 1432 * callback kept a lock held, bad luck, but not worse 1433 * than the BUG() we had. 1434 */ 1435 preempt_count_set(count); 1436 } 1437 } 1438 1439 static void expire_timers(struct timer_base *base, struct hlist_head *head) 1440 { 1441 /* 1442 * This value is required only for tracing. base->clk was 1443 * incremented directly before expire_timers was called. But expiry 1444 * is related to the old base->clk value. 1445 */ 1446 unsigned long baseclk = base->clk - 1; 1447 1448 while (!hlist_empty(head)) { 1449 struct timer_list *timer; 1450 void (*fn)(struct timer_list *); 1451 1452 timer = hlist_entry(head->first, struct timer_list, entry); 1453 1454 base->running_timer = timer; 1455 detach_timer(timer, true); 1456 1457 fn = timer->function; 1458 1459 if (timer->flags & TIMER_IRQSAFE) { 1460 raw_spin_unlock(&base->lock); 1461 call_timer_fn(timer, fn, baseclk); 1462 raw_spin_lock(&base->lock); 1463 base->running_timer = NULL; 1464 } else { 1465 raw_spin_unlock_irq(&base->lock); 1466 call_timer_fn(timer, fn, baseclk); 1467 raw_spin_lock_irq(&base->lock); 1468 base->running_timer = NULL; 1469 timer_sync_wait_running(base); 1470 } 1471 } 1472 } 1473 1474 static int collect_expired_timers(struct timer_base *base, 1475 struct hlist_head *heads) 1476 { 1477 unsigned long clk = base->clk = base->next_expiry; 1478 struct hlist_head *vec; 1479 int i, levels = 0; 1480 unsigned int idx; 1481 1482 for (i = 0; i < LVL_DEPTH; i++) { 1483 idx = (clk & LVL_MASK) + i * LVL_SIZE; 1484 1485 if (__test_and_clear_bit(idx, base->pending_map)) { 1486 vec = base->vectors + idx; 1487 hlist_move_list(vec, heads++); 1488 levels++; 1489 } 1490 /* Is it time to look at the next level? */ 1491 if (clk & LVL_CLK_MASK) 1492 break; 1493 /* Shift clock for the next level granularity */ 1494 clk >>= LVL_CLK_SHIFT; 1495 } 1496 return levels; 1497 } 1498 1499 /* 1500 * Find the next pending bucket of a level. Search from level start (@offset) 1501 * + @clk upwards and if nothing there, search from start of the level 1502 * (@offset) up to @offset + clk. 1503 */ 1504 static int next_pending_bucket(struct timer_base *base, unsigned offset, 1505 unsigned clk) 1506 { 1507 unsigned pos, start = offset + clk; 1508 unsigned end = offset + LVL_SIZE; 1509 1510 pos = find_next_bit(base->pending_map, end, start); 1511 if (pos < end) 1512 return pos - start; 1513 1514 pos = find_next_bit(base->pending_map, start, offset); 1515 return pos < start ? pos + LVL_SIZE - start : -1; 1516 } 1517 1518 /* 1519 * Search the first expiring timer in the various clock levels. Caller must 1520 * hold base->lock. 1521 */ 1522 static unsigned long __next_timer_interrupt(struct timer_base *base) 1523 { 1524 unsigned long clk, next, adj; 1525 unsigned lvl, offset = 0; 1526 1527 next = base->clk + NEXT_TIMER_MAX_DELTA; 1528 clk = base->clk; 1529 for (lvl = 0; lvl < LVL_DEPTH; lvl++, offset += LVL_SIZE) { 1530 int pos = next_pending_bucket(base, offset, clk & LVL_MASK); 1531 unsigned long lvl_clk = clk & LVL_CLK_MASK; 1532 1533 if (pos >= 0) { 1534 unsigned long tmp = clk + (unsigned long) pos; 1535 1536 tmp <<= LVL_SHIFT(lvl); 1537 if (time_before(tmp, next)) 1538 next = tmp; 1539 1540 /* 1541 * If the next expiration happens before we reach 1542 * the next level, no need to check further. 1543 */ 1544 if (pos <= ((LVL_CLK_DIV - lvl_clk) & LVL_CLK_MASK)) 1545 break; 1546 } 1547 /* 1548 * Clock for the next level. If the current level clock lower 1549 * bits are zero, we look at the next level as is. If not we 1550 * need to advance it by one because that's going to be the 1551 * next expiring bucket in that level. base->clk is the next 1552 * expiring jiffie. So in case of: 1553 * 1554 * LVL5 LVL4 LVL3 LVL2 LVL1 LVL0 1555 * 0 0 0 0 0 0 1556 * 1557 * we have to look at all levels @index 0. With 1558 * 1559 * LVL5 LVL4 LVL3 LVL2 LVL1 LVL0 1560 * 0 0 0 0 0 2 1561 * 1562 * LVL0 has the next expiring bucket @index 2. The upper 1563 * levels have the next expiring bucket @index 1. 1564 * 1565 * In case that the propagation wraps the next level the same 1566 * rules apply: 1567 * 1568 * LVL5 LVL4 LVL3 LVL2 LVL1 LVL0 1569 * 0 0 0 0 F 2 1570 * 1571 * So after looking at LVL0 we get: 1572 * 1573 * LVL5 LVL4 LVL3 LVL2 LVL1 1574 * 0 0 0 1 0 1575 * 1576 * So no propagation from LVL1 to LVL2 because that happened 1577 * with the add already, but then we need to propagate further 1578 * from LVL2 to LVL3. 1579 * 1580 * So the simple check whether the lower bits of the current 1581 * level are 0 or not is sufficient for all cases. 1582 */ 1583 adj = lvl_clk ? 1 : 0; 1584 clk >>= LVL_CLK_SHIFT; 1585 clk += adj; 1586 } 1587 1588 base->next_expiry_recalc = false; 1589 base->timers_pending = !(next == base->clk + NEXT_TIMER_MAX_DELTA); 1590 1591 return next; 1592 } 1593 1594 #ifdef CONFIG_NO_HZ_COMMON 1595 /* 1596 * Check, if the next hrtimer event is before the next timer wheel 1597 * event: 1598 */ 1599 static u64 cmp_next_hrtimer_event(u64 basem, u64 expires) 1600 { 1601 u64 nextevt = hrtimer_get_next_event(); 1602 1603 /* 1604 * If high resolution timers are enabled 1605 * hrtimer_get_next_event() returns KTIME_MAX. 1606 */ 1607 if (expires <= nextevt) 1608 return expires; 1609 1610 /* 1611 * If the next timer is already expired, return the tick base 1612 * time so the tick is fired immediately. 1613 */ 1614 if (nextevt <= basem) 1615 return basem; 1616 1617 /* 1618 * Round up to the next jiffie. High resolution timers are 1619 * off, so the hrtimers are expired in the tick and we need to 1620 * make sure that this tick really expires the timer to avoid 1621 * a ping pong of the nohz stop code. 1622 * 1623 * Use DIV_ROUND_UP_ULL to prevent gcc calling __divdi3 1624 */ 1625 return DIV_ROUND_UP_ULL(nextevt, TICK_NSEC) * TICK_NSEC; 1626 } 1627 1628 /** 1629 * get_next_timer_interrupt - return the time (clock mono) of the next timer 1630 * @basej: base time jiffies 1631 * @basem: base time clock monotonic 1632 * 1633 * Returns the tick aligned clock monotonic time of the next pending 1634 * timer or KTIME_MAX if no timer is pending. 1635 */ 1636 u64 get_next_timer_interrupt(unsigned long basej, u64 basem) 1637 { 1638 struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]); 1639 u64 expires = KTIME_MAX; 1640 unsigned long nextevt; 1641 1642 /* 1643 * Pretend that there is no timer pending if the cpu is offline. 1644 * Possible pending timers will be migrated later to an active cpu. 1645 */ 1646 if (cpu_is_offline(smp_processor_id())) 1647 return expires; 1648 1649 raw_spin_lock(&base->lock); 1650 if (base->next_expiry_recalc) 1651 base->next_expiry = __next_timer_interrupt(base); 1652 nextevt = base->next_expiry; 1653 1654 /* 1655 * We have a fresh next event. Check whether we can forward the 1656 * base. We can only do that when @basej is past base->clk 1657 * otherwise we might rewind base->clk. 1658 */ 1659 if (time_after(basej, base->clk)) { 1660 if (time_after(nextevt, basej)) 1661 base->clk = basej; 1662 else if (time_after(nextevt, base->clk)) 1663 base->clk = nextevt; 1664 } 1665 1666 if (time_before_eq(nextevt, basej)) { 1667 expires = basem; 1668 base->is_idle = false; 1669 } else { 1670 if (base->timers_pending) 1671 expires = basem + (u64)(nextevt - basej) * TICK_NSEC; 1672 /* 1673 * If we expect to sleep more than a tick, mark the base idle. 1674 * Also the tick is stopped so any added timer must forward 1675 * the base clk itself to keep granularity small. This idle 1676 * logic is only maintained for the BASE_STD base, deferrable 1677 * timers may still see large granularity skew (by design). 1678 */ 1679 if ((expires - basem) > TICK_NSEC) 1680 base->is_idle = true; 1681 } 1682 raw_spin_unlock(&base->lock); 1683 1684 return cmp_next_hrtimer_event(basem, expires); 1685 } 1686 1687 /** 1688 * timer_clear_idle - Clear the idle state of the timer base 1689 * 1690 * Called with interrupts disabled 1691 */ 1692 void timer_clear_idle(void) 1693 { 1694 struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]); 1695 1696 /* 1697 * We do this unlocked. The worst outcome is a remote enqueue sending 1698 * a pointless IPI, but taking the lock would just make the window for 1699 * sending the IPI a few instructions smaller for the cost of taking 1700 * the lock in the exit from idle path. 1701 */ 1702 base->is_idle = false; 1703 } 1704 #endif 1705 1706 /** 1707 * __run_timers - run all expired timers (if any) on this CPU. 1708 * @base: the timer vector to be processed. 1709 */ 1710 static inline void __run_timers(struct timer_base *base) 1711 { 1712 struct hlist_head heads[LVL_DEPTH]; 1713 int levels; 1714 1715 if (time_before(jiffies, base->next_expiry)) 1716 return; 1717 1718 timer_base_lock_expiry(base); 1719 raw_spin_lock_irq(&base->lock); 1720 1721 while (time_after_eq(jiffies, base->clk) && 1722 time_after_eq(jiffies, base->next_expiry)) { 1723 levels = collect_expired_timers(base, heads); 1724 /* 1725 * The only possible reason for not finding any expired 1726 * timer at this clk is that all matching timers have been 1727 * dequeued. 1728 */ 1729 WARN_ON_ONCE(!levels && !base->next_expiry_recalc); 1730 base->clk++; 1731 base->next_expiry = __next_timer_interrupt(base); 1732 1733 while (levels--) 1734 expire_timers(base, heads + levels); 1735 } 1736 raw_spin_unlock_irq(&base->lock); 1737 timer_base_unlock_expiry(base); 1738 } 1739 1740 /* 1741 * This function runs timers and the timer-tq in bottom half context. 1742 */ 1743 static __latent_entropy void run_timer_softirq(struct softirq_action *h) 1744 { 1745 struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]); 1746 1747 __run_timers(base); 1748 if (IS_ENABLED(CONFIG_NO_HZ_COMMON)) 1749 __run_timers(this_cpu_ptr(&timer_bases[BASE_DEF])); 1750 } 1751 1752 /* 1753 * Called by the local, per-CPU timer interrupt on SMP. 1754 */ 1755 static void run_local_timers(void) 1756 { 1757 struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]); 1758 1759 hrtimer_run_queues(); 1760 /* Raise the softirq only if required. */ 1761 if (time_before(jiffies, base->next_expiry)) { 1762 if (!IS_ENABLED(CONFIG_NO_HZ_COMMON)) 1763 return; 1764 /* CPU is awake, so check the deferrable base. */ 1765 base++; 1766 if (time_before(jiffies, base->next_expiry)) 1767 return; 1768 } 1769 raise_softirq(TIMER_SOFTIRQ); 1770 } 1771 1772 /* 1773 * Called from the timer interrupt handler to charge one tick to the current 1774 * process. user_tick is 1 if the tick is user time, 0 for system. 1775 */ 1776 void update_process_times(int user_tick) 1777 { 1778 struct task_struct *p = current; 1779 1780 PRANDOM_ADD_NOISE(jiffies, user_tick, p, 0); 1781 1782 /* Note: this timer irq context must be accounted for as well. */ 1783 account_process_tick(p, user_tick); 1784 run_local_timers(); 1785 rcu_sched_clock_irq(user_tick); 1786 #ifdef CONFIG_IRQ_WORK 1787 if (in_irq()) 1788 irq_work_tick(); 1789 #endif 1790 scheduler_tick(); 1791 if (IS_ENABLED(CONFIG_POSIX_TIMERS)) 1792 run_posix_cpu_timers(); 1793 } 1794 1795 /* 1796 * Since schedule_timeout()'s timer is defined on the stack, it must store 1797 * the target task on the stack as well. 1798 */ 1799 struct process_timer { 1800 struct timer_list timer; 1801 struct task_struct *task; 1802 }; 1803 1804 static void process_timeout(struct timer_list *t) 1805 { 1806 struct process_timer *timeout = from_timer(timeout, t, timer); 1807 1808 wake_up_process(timeout->task); 1809 } 1810 1811 /** 1812 * schedule_timeout - sleep until timeout 1813 * @timeout: timeout value in jiffies 1814 * 1815 * Make the current task sleep until @timeout jiffies have elapsed. 1816 * The function behavior depends on the current task state 1817 * (see also set_current_state() description): 1818 * 1819 * %TASK_RUNNING - the scheduler is called, but the task does not sleep 1820 * at all. That happens because sched_submit_work() does nothing for 1821 * tasks in %TASK_RUNNING state. 1822 * 1823 * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to 1824 * pass before the routine returns unless the current task is explicitly 1825 * woken up, (e.g. by wake_up_process()). 1826 * 1827 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is 1828 * delivered to the current task or the current task is explicitly woken 1829 * up. 1830 * 1831 * The current task state is guaranteed to be %TASK_RUNNING when this 1832 * routine returns. 1833 * 1834 * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule 1835 * the CPU away without a bound on the timeout. In this case the return 1836 * value will be %MAX_SCHEDULE_TIMEOUT. 1837 * 1838 * Returns 0 when the timer has expired otherwise the remaining time in 1839 * jiffies will be returned. In all cases the return value is guaranteed 1840 * to be non-negative. 1841 */ 1842 signed long __sched schedule_timeout(signed long timeout) 1843 { 1844 struct process_timer timer; 1845 unsigned long expire; 1846 1847 switch (timeout) 1848 { 1849 case MAX_SCHEDULE_TIMEOUT: 1850 /* 1851 * These two special cases are useful to be comfortable 1852 * in the caller. Nothing more. We could take 1853 * MAX_SCHEDULE_TIMEOUT from one of the negative value 1854 * but I' d like to return a valid offset (>=0) to allow 1855 * the caller to do everything it want with the retval. 1856 */ 1857 schedule(); 1858 goto out; 1859 default: 1860 /* 1861 * Another bit of PARANOID. Note that the retval will be 1862 * 0 since no piece of kernel is supposed to do a check 1863 * for a negative retval of schedule_timeout() (since it 1864 * should never happens anyway). You just have the printk() 1865 * that will tell you if something is gone wrong and where. 1866 */ 1867 if (timeout < 0) { 1868 printk(KERN_ERR "schedule_timeout: wrong timeout " 1869 "value %lx\n", timeout); 1870 dump_stack(); 1871 __set_current_state(TASK_RUNNING); 1872 goto out; 1873 } 1874 } 1875 1876 expire = timeout + jiffies; 1877 1878 timer.task = current; 1879 timer_setup_on_stack(&timer.timer, process_timeout, 0); 1880 __mod_timer(&timer.timer, expire, MOD_TIMER_NOTPENDING); 1881 schedule(); 1882 del_singleshot_timer_sync(&timer.timer); 1883 1884 /* Remove the timer from the object tracker */ 1885 destroy_timer_on_stack(&timer.timer); 1886 1887 timeout = expire - jiffies; 1888 1889 out: 1890 return timeout < 0 ? 0 : timeout; 1891 } 1892 EXPORT_SYMBOL(schedule_timeout); 1893 1894 /* 1895 * We can use __set_current_state() here because schedule_timeout() calls 1896 * schedule() unconditionally. 1897 */ 1898 signed long __sched schedule_timeout_interruptible(signed long timeout) 1899 { 1900 __set_current_state(TASK_INTERRUPTIBLE); 1901 return schedule_timeout(timeout); 1902 } 1903 EXPORT_SYMBOL(schedule_timeout_interruptible); 1904 1905 signed long __sched schedule_timeout_killable(signed long timeout) 1906 { 1907 __set_current_state(TASK_KILLABLE); 1908 return schedule_timeout(timeout); 1909 } 1910 EXPORT_SYMBOL(schedule_timeout_killable); 1911 1912 signed long __sched schedule_timeout_uninterruptible(signed long timeout) 1913 { 1914 __set_current_state(TASK_UNINTERRUPTIBLE); 1915 return schedule_timeout(timeout); 1916 } 1917 EXPORT_SYMBOL(schedule_timeout_uninterruptible); 1918 1919 /* 1920 * Like schedule_timeout_uninterruptible(), except this task will not contribute 1921 * to load average. 1922 */ 1923 signed long __sched schedule_timeout_idle(signed long timeout) 1924 { 1925 __set_current_state(TASK_IDLE); 1926 return schedule_timeout(timeout); 1927 } 1928 EXPORT_SYMBOL(schedule_timeout_idle); 1929 1930 #ifdef CONFIG_HOTPLUG_CPU 1931 static void migrate_timer_list(struct timer_base *new_base, struct hlist_head *head) 1932 { 1933 struct timer_list *timer; 1934 int cpu = new_base->cpu; 1935 1936 while (!hlist_empty(head)) { 1937 timer = hlist_entry(head->first, struct timer_list, entry); 1938 detach_timer(timer, false); 1939 timer->flags = (timer->flags & ~TIMER_BASEMASK) | cpu; 1940 internal_add_timer(new_base, timer); 1941 } 1942 } 1943 1944 int timers_prepare_cpu(unsigned int cpu) 1945 { 1946 struct timer_base *base; 1947 int b; 1948 1949 for (b = 0; b < NR_BASES; b++) { 1950 base = per_cpu_ptr(&timer_bases[b], cpu); 1951 base->clk = jiffies; 1952 base->next_expiry = base->clk + NEXT_TIMER_MAX_DELTA; 1953 base->timers_pending = false; 1954 base->is_idle = false; 1955 } 1956 return 0; 1957 } 1958 1959 int timers_dead_cpu(unsigned int cpu) 1960 { 1961 struct timer_base *old_base; 1962 struct timer_base *new_base; 1963 int b, i; 1964 1965 BUG_ON(cpu_online(cpu)); 1966 1967 for (b = 0; b < NR_BASES; b++) { 1968 old_base = per_cpu_ptr(&timer_bases[b], cpu); 1969 new_base = get_cpu_ptr(&timer_bases[b]); 1970 /* 1971 * The caller is globally serialized and nobody else 1972 * takes two locks at once, deadlock is not possible. 1973 */ 1974 raw_spin_lock_irq(&new_base->lock); 1975 raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING); 1976 1977 /* 1978 * The current CPUs base clock might be stale. Update it 1979 * before moving the timers over. 1980 */ 1981 forward_timer_base(new_base); 1982 1983 BUG_ON(old_base->running_timer); 1984 1985 for (i = 0; i < WHEEL_SIZE; i++) 1986 migrate_timer_list(new_base, old_base->vectors + i); 1987 1988 raw_spin_unlock(&old_base->lock); 1989 raw_spin_unlock_irq(&new_base->lock); 1990 put_cpu_ptr(&timer_bases); 1991 } 1992 return 0; 1993 } 1994 1995 #endif /* CONFIG_HOTPLUG_CPU */ 1996 1997 static void __init init_timer_cpu(int cpu) 1998 { 1999 struct timer_base *base; 2000 int i; 2001 2002 for (i = 0; i < NR_BASES; i++) { 2003 base = per_cpu_ptr(&timer_bases[i], cpu); 2004 base->cpu = cpu; 2005 raw_spin_lock_init(&base->lock); 2006 base->clk = jiffies; 2007 base->next_expiry = base->clk + NEXT_TIMER_MAX_DELTA; 2008 timer_base_init_expiry_lock(base); 2009 } 2010 } 2011 2012 static void __init init_timer_cpus(void) 2013 { 2014 int cpu; 2015 2016 for_each_possible_cpu(cpu) 2017 init_timer_cpu(cpu); 2018 } 2019 2020 void __init init_timers(void) 2021 { 2022 init_timer_cpus(); 2023 posix_cputimers_init_work(); 2024 open_softirq(TIMER_SOFTIRQ, run_timer_softirq); 2025 } 2026 2027 /** 2028 * msleep - sleep safely even with waitqueue interruptions 2029 * @msecs: Time in milliseconds to sleep for 2030 */ 2031 void msleep(unsigned int msecs) 2032 { 2033 unsigned long timeout = msecs_to_jiffies(msecs) + 1; 2034 2035 while (timeout) 2036 timeout = schedule_timeout_uninterruptible(timeout); 2037 } 2038 2039 EXPORT_SYMBOL(msleep); 2040 2041 /** 2042 * msleep_interruptible - sleep waiting for signals 2043 * @msecs: Time in milliseconds to sleep for 2044 */ 2045 unsigned long msleep_interruptible(unsigned int msecs) 2046 { 2047 unsigned long timeout = msecs_to_jiffies(msecs) + 1; 2048 2049 while (timeout && !signal_pending(current)) 2050 timeout = schedule_timeout_interruptible(timeout); 2051 return jiffies_to_msecs(timeout); 2052 } 2053 2054 EXPORT_SYMBOL(msleep_interruptible); 2055 2056 /** 2057 * usleep_range - Sleep for an approximate time 2058 * @min: Minimum time in usecs to sleep 2059 * @max: Maximum time in usecs to sleep 2060 * 2061 * In non-atomic context where the exact wakeup time is flexible, use 2062 * usleep_range() instead of udelay(). The sleep improves responsiveness 2063 * by avoiding the CPU-hogging busy-wait of udelay(), and the range reduces 2064 * power usage by allowing hrtimers to take advantage of an already- 2065 * scheduled interrupt instead of scheduling a new one just for this sleep. 2066 */ 2067 void __sched usleep_range(unsigned long min, unsigned long max) 2068 { 2069 ktime_t exp = ktime_add_us(ktime_get(), min); 2070 u64 delta = (u64)(max - min) * NSEC_PER_USEC; 2071 2072 for (;;) { 2073 __set_current_state(TASK_UNINTERRUPTIBLE); 2074 /* Do not return before the requested sleep time has elapsed */ 2075 if (!schedule_hrtimeout_range(&exp, delta, HRTIMER_MODE_ABS)) 2076 break; 2077 } 2078 } 2079 EXPORT_SYMBOL(usleep_range); 2080