1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1982, 1986, 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * (c) UNIX System Laboratories, Inc. 7 * All or some portions of this file are derived from material licensed 8 * to the University of California by American Telephone and Telegraph 9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 10 * the permission of UNIX System Laboratories, Inc. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #include <sys/cdefs.h> 38 #include "opt_callout_profiling.h" 39 #include "opt_ddb.h" 40 #include "opt_rss.h" 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/bus.h> 45 #include <sys/callout.h> 46 #include <sys/domainset.h> 47 #include <sys/file.h> 48 #include <sys/interrupt.h> 49 #include <sys/kernel.h> 50 #include <sys/ktr.h> 51 #include <sys/kthread.h> 52 #include <sys/lock.h> 53 #include <sys/malloc.h> 54 #include <sys/mutex.h> 55 #include <sys/proc.h> 56 #include <sys/random.h> 57 #include <sys/sched.h> 58 #include <sys/sdt.h> 59 #include <sys/sleepqueue.h> 60 #include <sys/sysctl.h> 61 #include <sys/smp.h> 62 #include <sys/unistd.h> 63 64 #ifdef DDB 65 #include <ddb/ddb.h> 66 #include <ddb/db_sym.h> 67 #include <machine/_inttypes.h> 68 #endif 69 70 #ifdef SMP 71 #include <machine/cpu.h> 72 #endif 73 74 DPCPU_DECLARE(sbintime_t, hardclocktime); 75 76 SDT_PROVIDER_DEFINE(callout_execute); 77 SDT_PROBE_DEFINE1(callout_execute, , , callout__start, "struct callout *"); 78 SDT_PROBE_DEFINE1(callout_execute, , , callout__end, "struct callout *"); 79 80 static void softclock_thread(void *arg); 81 82 #ifdef CALLOUT_PROFILING 83 static int avg_depth; 84 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0, 85 "Average number of items examined per softclock call. Units = 1/1000"); 86 static int avg_gcalls; 87 SYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0, 88 "Average number of Giant callouts made per softclock call. Units = 1/1000"); 89 static int avg_lockcalls; 90 SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls, CTLFLAG_RD, &avg_lockcalls, 0, 91 "Average number of lock callouts made per softclock call. Units = 1/1000"); 92 static int avg_mpcalls; 93 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0, 94 "Average number of MP callouts made per softclock call. Units = 1/1000"); 95 static int avg_depth_dir; 96 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth_dir, CTLFLAG_RD, &avg_depth_dir, 0, 97 "Average number of direct callouts examined per callout_process call. " 98 "Units = 1/1000"); 99 static int avg_lockcalls_dir; 100 SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls_dir, CTLFLAG_RD, 101 &avg_lockcalls_dir, 0, "Average number of lock direct callouts made per " 102 "callout_process call. Units = 1/1000"); 103 static int avg_mpcalls_dir; 104 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls_dir, CTLFLAG_RD, &avg_mpcalls_dir, 105 0, "Average number of MP direct callouts made per callout_process call. " 106 "Units = 1/1000"); 107 #endif 108 109 static int ncallout; 110 SYSCTL_INT(_kern, OID_AUTO, ncallout, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &ncallout, 0, 111 "Number of entries in callwheel and size of timeout() preallocation"); 112 113 #ifdef RSS 114 static int pin_default_swi = 1; 115 static int pin_pcpu_swi = 1; 116 #else 117 static int pin_default_swi = 0; 118 static int pin_pcpu_swi = 0; 119 #endif 120 121 SYSCTL_INT(_kern, OID_AUTO, pin_default_swi, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &pin_default_swi, 122 0, "Pin the default (non-per-cpu) swi (shared with PCPU 0 swi)"); 123 SYSCTL_INT(_kern, OID_AUTO, pin_pcpu_swi, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &pin_pcpu_swi, 124 0, "Pin the per-CPU swis (except PCPU 0, which is also default)"); 125 126 /* 127 * TODO: 128 * allocate more timeout table slots when table overflows. 129 */ 130 static u_int __read_mostly callwheelsize; 131 static u_int __read_mostly callwheelmask; 132 133 /* 134 * The callout cpu exec entities represent informations necessary for 135 * describing the state of callouts currently running on the CPU and the ones 136 * necessary for migrating callouts to the new callout cpu. In particular, 137 * the first entry of the array cc_exec_entity holds informations for callout 138 * running in SWI thread context, while the second one holds informations 139 * for callout running directly from hardware interrupt context. 140 * The cached informations are very important for deferring migration when 141 * the migrating callout is already running. 142 */ 143 struct cc_exec { 144 struct callout *cc_curr; 145 void *cc_last_func; 146 void *cc_last_arg; 147 #ifdef SMP 148 callout_func_t *ce_migration_func; 149 void *ce_migration_arg; 150 sbintime_t ce_migration_time; 151 sbintime_t ce_migration_prec; 152 int ce_migration_cpu; 153 #endif 154 bool cc_cancel; 155 bool cc_waiting; 156 }; 157 158 /* 159 * There is one struct callout_cpu per cpu, holding all relevant 160 * state for the callout processing thread on the individual CPU. 161 */ 162 struct callout_cpu { 163 struct mtx_padalign cc_lock; 164 struct cc_exec cc_exec_entity[2]; 165 struct callout *cc_next; 166 struct callout_list *cc_callwheel; 167 struct callout_tailq cc_expireq; 168 sbintime_t cc_firstevent; 169 sbintime_t cc_lastscan; 170 struct thread *cc_thread; 171 u_int cc_bucket; 172 #ifdef KTR 173 char cc_ktr_event_name[20]; 174 #endif 175 }; 176 177 #define callout_migrating(c) ((c)->c_iflags & CALLOUT_DFRMIGRATION) 178 179 #define cc_exec_curr(cc, dir) cc->cc_exec_entity[dir].cc_curr 180 #define cc_exec_last_func(cc, dir) cc->cc_exec_entity[dir].cc_last_func 181 #define cc_exec_last_arg(cc, dir) cc->cc_exec_entity[dir].cc_last_arg 182 #define cc_exec_next(cc) cc->cc_next 183 #define cc_exec_cancel(cc, dir) cc->cc_exec_entity[dir].cc_cancel 184 #define cc_exec_waiting(cc, dir) cc->cc_exec_entity[dir].cc_waiting 185 #ifdef SMP 186 #define cc_migration_func(cc, dir) cc->cc_exec_entity[dir].ce_migration_func 187 #define cc_migration_arg(cc, dir) cc->cc_exec_entity[dir].ce_migration_arg 188 #define cc_migration_cpu(cc, dir) cc->cc_exec_entity[dir].ce_migration_cpu 189 #define cc_migration_time(cc, dir) cc->cc_exec_entity[dir].ce_migration_time 190 #define cc_migration_prec(cc, dir) cc->cc_exec_entity[dir].ce_migration_prec 191 192 DPCPU_DEFINE_STATIC(struct callout_cpu, cc_cpu); 193 #define CPUBLOCK MAXCPU 194 #define CC_CPU(cpu) DPCPU_ID_PTR(cpu, cc_cpu) 195 #define CC_SELF() CC_CPU(PCPU_GET(cpuid)) 196 #else 197 static struct callout_cpu cc_cpu; 198 #define CC_CPU(cpu) (&cc_cpu) 199 #define CC_SELF() (&cc_cpu) 200 #endif 201 #define CC_LOCK(cc) mtx_lock_spin(&(cc)->cc_lock) 202 #define CC_UNLOCK(cc) mtx_unlock_spin(&(cc)->cc_lock) 203 #define CC_LOCK_ASSERT(cc) mtx_assert(&(cc)->cc_lock, MA_OWNED) 204 205 static int __read_mostly cc_default_cpu; 206 207 static void callout_cpu_init(struct callout_cpu *cc, int cpu); 208 static void softclock_call_cc(struct callout *c, struct callout_cpu *cc, 209 #ifdef CALLOUT_PROFILING 210 int *mpcalls, int *lockcalls, int *gcalls, 211 #endif 212 int direct); 213 214 static MALLOC_DEFINE(M_CALLOUT, "callout", "Callout datastructures"); 215 216 /** 217 * Locked by cc_lock: 218 * cc_curr - If a callout is in progress, it is cc_curr. 219 * If cc_curr is non-NULL, threads waiting in 220 * callout_drain() will be woken up as soon as the 221 * relevant callout completes. 222 * cc_cancel - Changing to 1 with both callout_lock and cc_lock held 223 * guarantees that the current callout will not run. 224 * The softclock_call_cc() function sets this to 0 before it 225 * drops callout_lock to acquire c_lock, and it calls 226 * the handler only if curr_cancelled is still 0 after 227 * cc_lock is successfully acquired. 228 * cc_waiting - If a thread is waiting in callout_drain(), then 229 * callout_wait is nonzero. Set only when 230 * cc_curr is non-NULL. 231 */ 232 233 /* 234 * Resets the execution entity tied to a specific callout cpu. 235 */ 236 static void cc_cce_cleanup(struct callout_cpu * cc,int direct)237 cc_cce_cleanup(struct callout_cpu *cc, int direct) 238 { 239 240 cc_exec_curr(cc, direct) = NULL; 241 cc_exec_cancel(cc, direct) = false; 242 cc_exec_waiting(cc, direct) = false; 243 #ifdef SMP 244 cc_migration_cpu(cc, direct) = CPUBLOCK; 245 cc_migration_time(cc, direct) = 0; 246 cc_migration_prec(cc, direct) = 0; 247 cc_migration_func(cc, direct) = NULL; 248 cc_migration_arg(cc, direct) = NULL; 249 #endif 250 } 251 252 /* 253 * Checks if migration is requested by a specific callout cpu. 254 */ 255 static int cc_cce_migrating(struct callout_cpu * cc,int direct)256 cc_cce_migrating(struct callout_cpu *cc, int direct) 257 { 258 259 #ifdef SMP 260 return (cc_migration_cpu(cc, direct) != CPUBLOCK); 261 #else 262 return (0); 263 #endif 264 } 265 266 /* 267 * Kernel low level callwheel initialization 268 * called on the BSP during kernel startup. 269 */ 270 static void callout_callwheel_init(void * dummy)271 callout_callwheel_init(void *dummy) 272 { 273 struct callout_cpu *cc; 274 int cpu; 275 276 /* 277 * Calculate the size of the callout wheel and the preallocated 278 * timeout() structures. 279 * XXX: Clip callout to result of previous function of maxusers 280 * maximum 384. This is still huge, but acceptable. 281 */ 282 ncallout = imin(16 + maxproc + maxfiles, 18508); 283 TUNABLE_INT_FETCH("kern.ncallout", &ncallout); 284 285 /* 286 * Calculate callout wheel size, should be next power of two higher 287 * than 'ncallout'. 288 */ 289 callwheelsize = 1 << fls(ncallout); 290 callwheelmask = callwheelsize - 1; 291 292 /* 293 * Fetch whether we're pinning the swi's or not. 294 */ 295 TUNABLE_INT_FETCH("kern.pin_default_swi", &pin_default_swi); 296 TUNABLE_INT_FETCH("kern.pin_pcpu_swi", &pin_pcpu_swi); 297 298 /* 299 * Initialize callout wheels. The software interrupt threads 300 * are created later. 301 */ 302 cc_default_cpu = PCPU_GET(cpuid); 303 CPU_FOREACH(cpu) { 304 cc = CC_CPU(cpu); 305 callout_cpu_init(cc, cpu); 306 } 307 } 308 SYSINIT(callwheel_init, SI_SUB_CPU, SI_ORDER_ANY, callout_callwheel_init, NULL); 309 310 /* 311 * Initialize the per-cpu callout structures. 312 */ 313 static void callout_cpu_init(struct callout_cpu * cc,int cpu)314 callout_cpu_init(struct callout_cpu *cc, int cpu) 315 { 316 int i; 317 318 mtx_init(&cc->cc_lock, "callout", NULL, MTX_SPIN); 319 cc->cc_callwheel = malloc_domainset(sizeof(struct callout_list) * 320 callwheelsize, M_CALLOUT, 321 DOMAINSET_PREF(pcpu_find(cpu)->pc_domain), M_WAITOK); 322 for (i = 0; i < callwheelsize; i++) 323 LIST_INIT(&cc->cc_callwheel[i]); 324 TAILQ_INIT(&cc->cc_expireq); 325 cc->cc_firstevent = SBT_MAX; 326 for (i = 0; i < 2; i++) 327 cc_cce_cleanup(cc, i); 328 #ifdef KTR 329 snprintf(cc->cc_ktr_event_name, sizeof(cc->cc_ktr_event_name), 330 "callwheel cpu %d", cpu); 331 #endif 332 } 333 334 #ifdef SMP 335 /* 336 * Switches the cpu tied to a specific callout. 337 * The function expects a locked incoming callout cpu and returns with 338 * locked outcoming callout cpu. 339 */ 340 static struct callout_cpu * callout_cpu_switch(struct callout * c,struct callout_cpu * cc,int new_cpu)341 callout_cpu_switch(struct callout *c, struct callout_cpu *cc, int new_cpu) 342 { 343 struct callout_cpu *new_cc; 344 345 MPASS(c != NULL && cc != NULL); 346 CC_LOCK_ASSERT(cc); 347 348 /* 349 * Avoid interrupts and preemption firing after the callout cpu 350 * is blocked in order to avoid deadlocks as the new thread 351 * may be willing to acquire the callout cpu lock. 352 */ 353 c->c_cpu = CPUBLOCK; 354 spinlock_enter(); 355 CC_UNLOCK(cc); 356 new_cc = CC_CPU(new_cpu); 357 CC_LOCK(new_cc); 358 spinlock_exit(); 359 c->c_cpu = new_cpu; 360 return (new_cc); 361 } 362 #endif 363 364 /* 365 * Start softclock threads. 366 */ 367 static void start_softclock(void * dummy)368 start_softclock(void *dummy) 369 { 370 struct proc *p; 371 struct thread *td; 372 struct callout_cpu *cc; 373 int cpu, error; 374 bool pin_swi; 375 376 p = NULL; 377 CPU_FOREACH(cpu) { 378 cc = CC_CPU(cpu); 379 error = kproc_kthread_add(softclock_thread, cc, &p, &td, 380 RFSTOPPED, 0, "clock", "clock (%d)", cpu); 381 if (error != 0) 382 panic("failed to create softclock thread for cpu %d: %d", 383 cpu, error); 384 CC_LOCK(cc); 385 cc->cc_thread = td; 386 thread_lock(td); 387 sched_class(td, PRI_ITHD); 388 sched_ithread_prio(td, PI_SOFTCLOCK); 389 TD_SET_IWAIT(td); 390 thread_lock_set(td, (struct mtx *)&cc->cc_lock); 391 thread_unlock(td); 392 if (cpu == cc_default_cpu) 393 pin_swi = pin_default_swi; 394 else 395 pin_swi = pin_pcpu_swi; 396 if (pin_swi) { 397 error = cpuset_setithread(td->td_tid, cpu); 398 if (error != 0) 399 printf("%s: %s clock couldn't be pinned to cpu %d: %d\n", 400 __func__, cpu == cc_default_cpu ? 401 "default" : "per-cpu", cpu, error); 402 } 403 } 404 } 405 SYSINIT(start_softclock, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_softclock, NULL); 406 407 #define CC_HASH_SHIFT 8 408 409 static inline u_int callout_hash(sbintime_t sbt)410 callout_hash(sbintime_t sbt) 411 { 412 413 return (sbt >> (32 - CC_HASH_SHIFT)); 414 } 415 416 static inline u_int callout_get_bucket(sbintime_t sbt)417 callout_get_bucket(sbintime_t sbt) 418 { 419 420 return (callout_hash(sbt) & callwheelmask); 421 } 422 423 void callout_process(sbintime_t now)424 callout_process(sbintime_t now) 425 { 426 struct callout_entropy { 427 struct callout_cpu *cc; 428 struct thread *td; 429 sbintime_t now; 430 } entropy; 431 struct callout *c, *next; 432 struct callout_cpu *cc; 433 struct callout_list *sc; 434 struct thread *td; 435 sbintime_t first, last, lookahead, max, tmp_max; 436 u_int firstb, lastb, nowb; 437 #ifdef CALLOUT_PROFILING 438 int depth_dir = 0, mpcalls_dir = 0, lockcalls_dir = 0; 439 #endif 440 441 cc = CC_SELF(); 442 mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET); 443 444 /* Compute the buckets of the last scan and present times. */ 445 firstb = callout_hash(cc->cc_lastscan); 446 cc->cc_lastscan = now; 447 nowb = callout_hash(now); 448 449 /* Compute the last bucket and minimum time of the bucket after it. */ 450 if (nowb == firstb) 451 lookahead = (SBT_1S / 16); 452 else if (nowb - firstb == 1) 453 lookahead = (SBT_1S / 8); 454 else 455 lookahead = SBT_1S; 456 first = last = now; 457 first += (lookahead / 2); 458 last += lookahead; 459 last &= (0xffffffffffffffffLLU << (32 - CC_HASH_SHIFT)); 460 lastb = callout_hash(last) - 1; 461 max = last; 462 463 /* 464 * Check if we wrapped around the entire wheel from the last scan. 465 * In case, we need to scan entirely the wheel for pending callouts. 466 */ 467 if (lastb - firstb >= callwheelsize) { 468 lastb = firstb + callwheelsize - 1; 469 if (nowb - firstb >= callwheelsize) 470 nowb = lastb; 471 } 472 473 /* Iterate callwheel from firstb to nowb and then up to lastb. */ 474 do { 475 sc = &cc->cc_callwheel[firstb & callwheelmask]; 476 LIST_FOREACH_SAFE(c, sc, c_links.le, next) { 477 /* Run the callout if present time within allowed. */ 478 if (c->c_time <= now) { 479 /* 480 * Consumer told us the callout may be run 481 * directly from hardware interrupt context. 482 */ 483 if (c->c_iflags & CALLOUT_DIRECT) { 484 #ifdef CALLOUT_PROFILING 485 ++depth_dir; 486 #endif 487 cc_exec_next(cc) = next; 488 cc->cc_bucket = firstb & callwheelmask; 489 LIST_REMOVE(c, c_links.le); 490 softclock_call_cc(c, cc, 491 #ifdef CALLOUT_PROFILING 492 &mpcalls_dir, &lockcalls_dir, NULL, 493 #endif 494 1); 495 next = cc_exec_next(cc); 496 cc_exec_next(cc) = NULL; 497 } else { 498 LIST_REMOVE(c, c_links.le); 499 TAILQ_INSERT_TAIL(&cc->cc_expireq, 500 c, c_links.tqe); 501 c->c_iflags |= CALLOUT_PROCESSED; 502 } 503 } else if (c->c_time >= max) { 504 /* 505 * Skip events in the distant future. 506 */ 507 ; 508 } else if (c->c_time > last) { 509 /* 510 * Event minimal time is bigger than present 511 * maximal time, so it cannot be aggregated. 512 */ 513 lastb = nowb; 514 } else { 515 /* 516 * Update first and last time, respecting this 517 * event. 518 */ 519 if (c->c_time < first) 520 first = c->c_time; 521 tmp_max = c->c_time + c->c_precision; 522 if (tmp_max < last) 523 last = tmp_max; 524 } 525 } 526 /* Proceed with the next bucket. */ 527 firstb++; 528 /* 529 * Stop if we looked after present time and found 530 * some event we can't execute at now. 531 * Stop if we looked far enough into the future. 532 */ 533 } while (((int)(firstb - lastb)) <= 0); 534 cc->cc_firstevent = last; 535 cpu_new_callout(curcpu, last, first); 536 537 #ifdef CALLOUT_PROFILING 538 avg_depth_dir += (depth_dir * 1000 - avg_depth_dir) >> 8; 539 avg_mpcalls_dir += (mpcalls_dir * 1000 - avg_mpcalls_dir) >> 8; 540 avg_lockcalls_dir += (lockcalls_dir * 1000 - avg_lockcalls_dir) >> 8; 541 #endif 542 if (!TAILQ_EMPTY(&cc->cc_expireq)) { 543 entropy.cc = cc; 544 entropy.td = curthread; 545 entropy.now = now; 546 random_harvest_queue(&entropy, sizeof(entropy), RANDOM_CALLOUT); 547 548 td = cc->cc_thread; 549 if (TD_AWAITING_INTR(td)) { 550 thread_lock_block_wait(td); 551 THREAD_LOCK_ASSERT(td, MA_OWNED); 552 TD_CLR_IWAIT(td); 553 sched_wakeup(td, SRQ_INTR); 554 } else 555 mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET); 556 } else 557 mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET); 558 } 559 560 static struct callout_cpu * callout_lock(struct callout * c)561 callout_lock(struct callout *c) 562 { 563 struct callout_cpu *cc; 564 int cpu; 565 566 for (;;) { 567 cpu = c->c_cpu; 568 #ifdef SMP 569 if (cpu == CPUBLOCK) { 570 while (c->c_cpu == CPUBLOCK) 571 cpu_spinwait(); 572 continue; 573 } 574 #endif 575 cc = CC_CPU(cpu); 576 CC_LOCK(cc); 577 if (cpu == c->c_cpu) 578 break; 579 CC_UNLOCK(cc); 580 } 581 return (cc); 582 } 583 584 static void callout_cc_add(struct callout * c,struct callout_cpu * cc,sbintime_t sbt,sbintime_t precision,void (* func)(void *),void * arg,int flags)585 callout_cc_add(struct callout *c, struct callout_cpu *cc, 586 sbintime_t sbt, sbintime_t precision, void (*func)(void *), 587 void *arg, int flags) 588 { 589 int bucket; 590 591 CC_LOCK_ASSERT(cc); 592 if (sbt < cc->cc_lastscan) 593 sbt = cc->cc_lastscan; 594 c->c_arg = arg; 595 c->c_iflags |= CALLOUT_PENDING; 596 c->c_iflags &= ~CALLOUT_PROCESSED; 597 c->c_flags |= CALLOUT_ACTIVE; 598 if (flags & C_DIRECT_EXEC) 599 c->c_iflags |= CALLOUT_DIRECT; 600 c->c_func = func; 601 c->c_time = sbt; 602 c->c_precision = precision; 603 bucket = callout_get_bucket(c->c_time); 604 CTR3(KTR_CALLOUT, "precision set for %p: %d.%08x", 605 c, (int)(c->c_precision >> 32), 606 (u_int)(c->c_precision & 0xffffffff)); 607 LIST_INSERT_HEAD(&cc->cc_callwheel[bucket], c, c_links.le); 608 if (cc->cc_bucket == bucket) 609 cc_exec_next(cc) = c; 610 611 /* 612 * Inform the eventtimers(4) subsystem there's a new callout 613 * that has been inserted, but only if really required. 614 */ 615 if (SBT_MAX - c->c_time < c->c_precision) 616 c->c_precision = SBT_MAX - c->c_time; 617 sbt = c->c_time + c->c_precision; 618 if (sbt < cc->cc_firstevent) { 619 cc->cc_firstevent = sbt; 620 cpu_new_callout(c->c_cpu, sbt, c->c_time); 621 } 622 } 623 624 static void softclock_call_cc(struct callout * c,struct callout_cpu * cc,int * mpcalls,int * lockcalls,int * gcalls,int direct)625 softclock_call_cc(struct callout *c, struct callout_cpu *cc, 626 #ifdef CALLOUT_PROFILING 627 int *mpcalls, int *lockcalls, int *gcalls, 628 #endif 629 int direct) 630 { 631 struct rm_priotracker tracker; 632 callout_func_t *c_func; 633 void *c_arg; 634 struct lock_class *class; 635 struct lock_object *c_lock; 636 uintptr_t lock_status; 637 int c_iflags; 638 #ifdef SMP 639 struct callout_cpu *new_cc; 640 callout_func_t *new_func; 641 void *new_arg; 642 int flags, new_cpu; 643 sbintime_t new_prec, new_time; 644 #endif 645 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING) 646 sbintime_t sbt1, sbt2; 647 struct timespec ts2; 648 static sbintime_t maxdt = 2 * SBT_1MS; /* 2 msec */ 649 static callout_func_t *lastfunc; 650 #endif 651 652 CC_LOCK_ASSERT(cc); 653 KASSERT((c->c_iflags & CALLOUT_PENDING) == CALLOUT_PENDING, 654 ("softclock_call_cc: pend %p %x", c, c->c_iflags)); 655 KASSERT((c->c_flags & CALLOUT_ACTIVE) == CALLOUT_ACTIVE, 656 ("softclock_call_cc: act %p %x", c, c->c_flags)); 657 class = (c->c_lock != NULL) ? LOCK_CLASS(c->c_lock) : NULL; 658 lock_status = 0; 659 if (c->c_iflags & CALLOUT_SHAREDLOCK) { 660 if (class == &lock_class_rm) 661 lock_status = (uintptr_t)&tracker; 662 else 663 lock_status = 1; 664 } 665 c_lock = c->c_lock; 666 c_func = c->c_func; 667 c_arg = c->c_arg; 668 c_iflags = c->c_iflags; 669 c->c_iflags &= ~CALLOUT_PENDING; 670 671 cc_exec_curr(cc, direct) = c; 672 cc_exec_last_func(cc, direct) = c_func; 673 cc_exec_last_arg(cc, direct) = c_arg; 674 cc_exec_cancel(cc, direct) = false; 675 if (c_lock != NULL) { 676 if (c_iflags & CALLOUT_TRYLOCK) { 677 if (__predict_false(class->lc_trylock(c_lock, 678 lock_status) == 0)) { 679 cc_exec_curr(cc, direct) = NULL; 680 callout_cc_add(c, cc, 681 cc->cc_lastscan + c->c_precision / 2, 682 qmax(c->c_precision / 2, 1), c_func, c_arg, 683 (direct) ? C_DIRECT_EXEC : 0); 684 return; 685 } 686 CC_UNLOCK(cc); 687 } else { 688 CC_UNLOCK(cc); 689 class->lc_lock(c_lock, lock_status); 690 /* 691 * The callout may have been cancelled 692 * while we switched locks. 693 */ 694 if (cc_exec_cancel(cc, direct)) { 695 class->lc_unlock(c_lock); 696 goto skip; 697 } 698 } 699 /* The callout cannot be stopped now. */ 700 cc_exec_cancel(cc, direct) = true; 701 if (c_lock == &Giant.lock_object) { 702 #ifdef CALLOUT_PROFILING 703 (*gcalls)++; 704 #endif 705 CTR3(KTR_CALLOUT, "callout giant %p func %p arg %p", 706 c, c_func, c_arg); 707 } else { 708 #ifdef CALLOUT_PROFILING 709 (*lockcalls)++; 710 #endif 711 CTR3(KTR_CALLOUT, "callout lock %p func %p arg %p", 712 c, c_func, c_arg); 713 } 714 } else { 715 CC_UNLOCK(cc); 716 #ifdef CALLOUT_PROFILING 717 (*mpcalls)++; 718 #endif 719 CTR3(KTR_CALLOUT, "callout %p func %p arg %p", 720 c, c_func, c_arg); 721 } 722 KTR_STATE3(KTR_SCHED, "callout", cc->cc_ktr_event_name, "running", 723 "func:%p", c_func, "arg:%p", c_arg, "direct:%d", direct); 724 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING) 725 sbt1 = sbinuptime(); 726 #endif 727 THREAD_NO_SLEEPING(); 728 SDT_PROBE1(callout_execute, , , callout__start, c); 729 c_func(c_arg); 730 SDT_PROBE1(callout_execute, , , callout__end, c); 731 THREAD_SLEEPING_OK(); 732 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING) 733 sbt2 = sbinuptime(); 734 sbt2 -= sbt1; 735 if (sbt2 > maxdt) { 736 if (lastfunc != c_func || sbt2 > maxdt * 2) { 737 ts2 = sbttots(sbt2); 738 printf( 739 "Expensive callout(9) function: %p(%p) %jd.%09ld s\n", 740 c_func, c_arg, (intmax_t)ts2.tv_sec, ts2.tv_nsec); 741 } 742 maxdt = sbt2; 743 lastfunc = c_func; 744 } 745 #endif 746 KTR_STATE0(KTR_SCHED, "callout", cc->cc_ktr_event_name, "idle"); 747 CTR1(KTR_CALLOUT, "callout %p finished", c); 748 if ((c_iflags & CALLOUT_RETURNUNLOCKED) == 0) 749 class->lc_unlock(c_lock); 750 skip: 751 CC_LOCK(cc); 752 KASSERT(cc_exec_curr(cc, direct) == c, ("mishandled cc_curr")); 753 cc_exec_curr(cc, direct) = NULL; 754 if (cc_exec_waiting(cc, direct)) { 755 /* 756 * There is someone waiting for the 757 * callout to complete. 758 * If the callout was scheduled for 759 * migration just cancel it. 760 */ 761 if (cc_cce_migrating(cc, direct)) { 762 cc_cce_cleanup(cc, direct); 763 764 /* 765 * It should be assert here that the callout is not 766 * destroyed but that is not easy. 767 */ 768 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 769 } 770 cc_exec_waiting(cc, direct) = false; 771 CC_UNLOCK(cc); 772 wakeup(&cc_exec_waiting(cc, direct)); 773 CC_LOCK(cc); 774 } else if (cc_cce_migrating(cc, direct)) { 775 #ifdef SMP 776 /* 777 * If the callout was scheduled for 778 * migration just perform it now. 779 */ 780 new_cpu = cc_migration_cpu(cc, direct); 781 new_time = cc_migration_time(cc, direct); 782 new_prec = cc_migration_prec(cc, direct); 783 new_func = cc_migration_func(cc, direct); 784 new_arg = cc_migration_arg(cc, direct); 785 cc_cce_cleanup(cc, direct); 786 787 /* 788 * It should be assert here that the callout is not destroyed 789 * but that is not easy. 790 * 791 * As first thing, handle deferred callout stops. 792 */ 793 if (!callout_migrating(c)) { 794 CTR3(KTR_CALLOUT, 795 "deferred cancelled %p func %p arg %p", 796 c, new_func, new_arg); 797 return; 798 } 799 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 800 801 new_cc = callout_cpu_switch(c, cc, new_cpu); 802 flags = (direct) ? C_DIRECT_EXEC : 0; 803 callout_cc_add(c, new_cc, new_time, new_prec, new_func, 804 new_arg, flags); 805 CC_UNLOCK(new_cc); 806 CC_LOCK(cc); 807 #else 808 panic("migration should not happen"); 809 #endif 810 } 811 } 812 813 /* 814 * The callout mechanism is based on the work of Adam M. Costello and 815 * George Varghese, published in a technical report entitled "Redesigning 816 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 817 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 818 * used in this implementation was published by G. Varghese and T. Lauck in 819 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 820 * the Efficient Implementation of a Timer Facility" in the Proceedings of 821 * the 11th ACM Annual Symposium on Operating Systems Principles, 822 * Austin, Texas Nov 1987. 823 */ 824 825 /* 826 * Software (low priority) clock interrupt thread handler. 827 * Run periodic events from timeout queue. 828 */ 829 static void softclock_thread(void * arg)830 softclock_thread(void *arg) 831 { 832 struct thread *td = curthread; 833 struct callout_cpu *cc; 834 struct callout *c; 835 #ifdef CALLOUT_PROFILING 836 int depth, gcalls, lockcalls, mpcalls; 837 #endif 838 839 cc = (struct callout_cpu *)arg; 840 CC_LOCK(cc); 841 for (;;) { 842 while (TAILQ_EMPTY(&cc->cc_expireq)) { 843 /* 844 * Use CC_LOCK(cc) as the thread_lock while 845 * idle. 846 */ 847 thread_lock(td); 848 thread_lock_set(td, (struct mtx *)&cc->cc_lock); 849 TD_SET_IWAIT(td); 850 mi_switch(SW_VOL | SWT_IWAIT); 851 852 /* mi_switch() drops thread_lock(). */ 853 CC_LOCK(cc); 854 } 855 856 #ifdef CALLOUT_PROFILING 857 depth = gcalls = lockcalls = mpcalls = 0; 858 #endif 859 while ((c = TAILQ_FIRST(&cc->cc_expireq)) != NULL) { 860 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe); 861 softclock_call_cc(c, cc, 862 #ifdef CALLOUT_PROFILING 863 &mpcalls, &lockcalls, &gcalls, 864 #endif 865 0); 866 #ifdef CALLOUT_PROFILING 867 ++depth; 868 #endif 869 } 870 #ifdef CALLOUT_PROFILING 871 avg_depth += (depth * 1000 - avg_depth) >> 8; 872 avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8; 873 avg_lockcalls += (lockcalls * 1000 - avg_lockcalls) >> 8; 874 avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8; 875 #endif 876 } 877 } 878 879 void callout_when(sbintime_t sbt,sbintime_t precision,int flags,sbintime_t * res,sbintime_t * prec_res)880 callout_when(sbintime_t sbt, sbintime_t precision, int flags, 881 sbintime_t *res, sbintime_t *prec_res) 882 { 883 sbintime_t to_sbt, to_pr; 884 885 if ((flags & (C_ABSOLUTE | C_PRECALC)) != 0) { 886 *res = sbt; 887 *prec_res = precision; 888 return; 889 } 890 if ((flags & C_HARDCLOCK) != 0 && sbt < tick_sbt) 891 sbt = tick_sbt; 892 if ((flags & C_HARDCLOCK) != 0 || sbt >= sbt_tickthreshold) { 893 /* 894 * Obtain the time of the last hardclock() call on 895 * this CPU directly from the kern_clocksource.c. 896 * This value is per-CPU, but it is equal for all 897 * active ones. 898 */ 899 #ifdef __LP64__ 900 to_sbt = DPCPU_GET(hardclocktime); 901 #else 902 spinlock_enter(); 903 to_sbt = DPCPU_GET(hardclocktime); 904 spinlock_exit(); 905 #endif 906 if (cold && to_sbt == 0) 907 to_sbt = sbinuptime(); 908 if ((flags & C_HARDCLOCK) == 0) 909 to_sbt += tick_sbt; 910 } else 911 to_sbt = sbinuptime(); 912 if (SBT_MAX - to_sbt < sbt) 913 to_sbt = SBT_MAX; 914 else 915 to_sbt += sbt; 916 *res = to_sbt; 917 to_pr = ((C_PRELGET(flags) < 0) ? sbt >> tc_precexp : 918 sbt >> C_PRELGET(flags)); 919 *prec_res = to_pr > precision ? to_pr : precision; 920 } 921 922 /* 923 * New interface; clients allocate their own callout structures. 924 * 925 * callout_reset() - establish or change a timeout 926 * callout_stop() - disestablish a timeout 927 * callout_init() - initialize a callout structure so that it can 928 * safely be passed to callout_reset() and callout_stop() 929 * 930 * <sys/callout.h> defines three convenience macros: 931 * 932 * callout_active() - returns truth if callout has not been stopped, 933 * drained, or deactivated since the last time the callout was 934 * reset. 935 * callout_pending() - returns truth if callout is still waiting for timeout 936 * callout_deactivate() - marks the callout as having been serviced 937 */ 938 int callout_reset_sbt_on(struct callout * c,sbintime_t sbt,sbintime_t prec,callout_func_t * ftn,void * arg,int cpu,int flags)939 callout_reset_sbt_on(struct callout *c, sbintime_t sbt, sbintime_t prec, 940 callout_func_t *ftn, void *arg, int cpu, int flags) 941 { 942 sbintime_t to_sbt, precision; 943 struct callout_cpu *cc; 944 int cancelled, direct; 945 946 cancelled = 0; 947 callout_when(sbt, prec, flags, &to_sbt, &precision); 948 949 /* 950 * This flag used to be added by callout_cc_add, but the 951 * first time you call this we could end up with the 952 * wrong direct flag if we don't do it before we add. 953 */ 954 if (flags & C_DIRECT_EXEC) { 955 direct = 1; 956 } else { 957 direct = 0; 958 } 959 KASSERT(!direct || c->c_lock == NULL || 960 (LOCK_CLASS(c->c_lock)->lc_flags & LC_SPINLOCK), 961 ("%s: direct callout %p has non-spin lock", __func__, c)); 962 963 cc = callout_lock(c); 964 if (cpu == -1) 965 cpu = c->c_cpu; 966 KASSERT(cpu >= 0 && cpu <= mp_maxid && !CPU_ABSENT(cpu), 967 ("%s: invalid cpu %d", __func__, cpu)); 968 969 if (cc_exec_curr(cc, direct) == c) { 970 /* 971 * We're being asked to reschedule a callout which is 972 * currently in progress. If there is a lock then we 973 * can cancel the callout if it has not really started. 974 */ 975 if (c->c_lock != NULL && !cc_exec_cancel(cc, direct)) 976 cancelled = cc_exec_cancel(cc, direct) = true; 977 if (cc_exec_waiting(cc, direct)) { 978 /* 979 * Someone has called callout_drain to kill this 980 * callout. Don't reschedule. 981 */ 982 CTR4(KTR_CALLOUT, "%s %p func %p arg %p", 983 cancelled ? "cancelled" : "failed to cancel", 984 c, c->c_func, c->c_arg); 985 CC_UNLOCK(cc); 986 return (cancelled); 987 } 988 #ifdef SMP 989 if (callout_migrating(c)) { 990 /* 991 * This only occurs when a second callout_reset_sbt_on 992 * is made after a previous one moved it into 993 * deferred migration (below). Note we do *not* change 994 * the prev_cpu even though the previous target may 995 * be different. 996 */ 997 cc_migration_cpu(cc, direct) = cpu; 998 cc_migration_time(cc, direct) = to_sbt; 999 cc_migration_prec(cc, direct) = precision; 1000 cc_migration_func(cc, direct) = ftn; 1001 cc_migration_arg(cc, direct) = arg; 1002 cancelled = 1; 1003 CC_UNLOCK(cc); 1004 return (cancelled); 1005 } 1006 #endif 1007 } 1008 if (c->c_iflags & CALLOUT_PENDING) { 1009 if ((c->c_iflags & CALLOUT_PROCESSED) == 0) { 1010 if (cc_exec_next(cc) == c) 1011 cc_exec_next(cc) = LIST_NEXT(c, c_links.le); 1012 LIST_REMOVE(c, c_links.le); 1013 } else { 1014 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe); 1015 } 1016 cancelled = 1; 1017 c->c_iflags &= ~ CALLOUT_PENDING; 1018 c->c_flags &= ~ CALLOUT_ACTIVE; 1019 } 1020 1021 #ifdef SMP 1022 /* 1023 * If the callout must migrate try to perform it immediately. 1024 * If the callout is currently running, just defer the migration 1025 * to a more appropriate moment. 1026 */ 1027 if (c->c_cpu != cpu) { 1028 if (cc_exec_curr(cc, direct) == c) { 1029 /* 1030 * Pending will have been removed since we are 1031 * actually executing the callout on another 1032 * CPU. That callout should be waiting on the 1033 * lock the caller holds. If we set both 1034 * active/and/pending after we return and the 1035 * lock on the executing callout proceeds, it 1036 * will then see pending is true and return. 1037 * At the return from the actual callout execution 1038 * the migration will occur in softclock_call_cc 1039 * and this new callout will be placed on the 1040 * new CPU via a call to callout_cpu_switch() which 1041 * will get the lock on the right CPU followed 1042 * by a call callout_cc_add() which will add it there. 1043 * (see above in softclock_call_cc()). 1044 */ 1045 cc_migration_cpu(cc, direct) = cpu; 1046 cc_migration_time(cc, direct) = to_sbt; 1047 cc_migration_prec(cc, direct) = precision; 1048 cc_migration_func(cc, direct) = ftn; 1049 cc_migration_arg(cc, direct) = arg; 1050 c->c_iflags |= (CALLOUT_DFRMIGRATION | CALLOUT_PENDING); 1051 c->c_flags |= CALLOUT_ACTIVE; 1052 CTR6(KTR_CALLOUT, 1053 "migration of %p func %p arg %p in %d.%08x to %u deferred", 1054 c, c->c_func, c->c_arg, (int)(to_sbt >> 32), 1055 (u_int)(to_sbt & 0xffffffff), cpu); 1056 CC_UNLOCK(cc); 1057 return (cancelled); 1058 } 1059 cc = callout_cpu_switch(c, cc, cpu); 1060 } 1061 #endif 1062 1063 callout_cc_add(c, cc, to_sbt, precision, ftn, arg, flags); 1064 CTR6(KTR_CALLOUT, "%sscheduled %p func %p arg %p in %d.%08x", 1065 cancelled ? "re" : "", c, c->c_func, c->c_arg, (int)(to_sbt >> 32), 1066 (u_int)(to_sbt & 0xffffffff)); 1067 CC_UNLOCK(cc); 1068 1069 return (cancelled); 1070 } 1071 1072 /* 1073 * Common idioms that can be optimized in the future. 1074 */ 1075 int callout_schedule_on(struct callout * c,int to_ticks,int cpu)1076 callout_schedule_on(struct callout *c, int to_ticks, int cpu) 1077 { 1078 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, cpu); 1079 } 1080 1081 int callout_schedule(struct callout * c,int to_ticks)1082 callout_schedule(struct callout *c, int to_ticks) 1083 { 1084 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, c->c_cpu); 1085 } 1086 1087 int _callout_stop_safe(struct callout * c,int flags)1088 _callout_stop_safe(struct callout *c, int flags) 1089 { 1090 struct callout_cpu *cc, *old_cc; 1091 struct lock_class *class; 1092 int direct, sq_locked, use_lock; 1093 int cancelled, not_on_a_list; 1094 1095 if ((flags & CS_DRAIN) != 0) 1096 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, c->c_lock, 1097 "calling %s", __func__); 1098 1099 /* 1100 * Some old subsystems don't hold Giant while running a callout_stop(), 1101 * so just discard this check for the moment. 1102 */ 1103 if ((flags & CS_DRAIN) == 0 && c->c_lock != NULL) { 1104 if (c->c_lock == &Giant.lock_object) 1105 use_lock = mtx_owned(&Giant); 1106 else { 1107 use_lock = 1; 1108 class = LOCK_CLASS(c->c_lock); 1109 class->lc_assert(c->c_lock, LA_XLOCKED); 1110 } 1111 } else 1112 use_lock = 0; 1113 if (c->c_iflags & CALLOUT_DIRECT) { 1114 direct = 1; 1115 } else { 1116 direct = 0; 1117 } 1118 sq_locked = 0; 1119 old_cc = NULL; 1120 again: 1121 cc = callout_lock(c); 1122 1123 if ((c->c_iflags & (CALLOUT_DFRMIGRATION | CALLOUT_PENDING)) == 1124 (CALLOUT_DFRMIGRATION | CALLOUT_PENDING) && 1125 ((c->c_flags & CALLOUT_ACTIVE) == CALLOUT_ACTIVE)) { 1126 /* 1127 * Special case where this slipped in while we 1128 * were migrating *as* the callout is about to 1129 * execute. The caller probably holds the lock 1130 * the callout wants. 1131 * 1132 * Get rid of the migration first. Then set 1133 * the flag that tells this code *not* to 1134 * try to remove it from any lists (its not 1135 * on one yet). When the callout wheel runs, 1136 * it will ignore this callout. 1137 */ 1138 c->c_iflags &= ~CALLOUT_PENDING; 1139 c->c_flags &= ~CALLOUT_ACTIVE; 1140 not_on_a_list = 1; 1141 } else { 1142 not_on_a_list = 0; 1143 } 1144 1145 /* 1146 * If the callout was migrating while the callout cpu lock was 1147 * dropped, just drop the sleepqueue lock and check the states 1148 * again. 1149 */ 1150 if (sq_locked != 0 && cc != old_cc) { 1151 #ifdef SMP 1152 CC_UNLOCK(cc); 1153 sleepq_release(&cc_exec_waiting(old_cc, direct)); 1154 sq_locked = 0; 1155 old_cc = NULL; 1156 goto again; 1157 #else 1158 panic("migration should not happen"); 1159 #endif 1160 } 1161 1162 /* 1163 * If the callout is running, try to stop it or drain it. 1164 */ 1165 if (cc_exec_curr(cc, direct) == c) { 1166 /* 1167 * Succeed we to stop it or not, we must clear the 1168 * active flag - this is what API users expect. If we're 1169 * draining and the callout is currently executing, first wait 1170 * until it finishes. 1171 */ 1172 if ((flags & CS_DRAIN) == 0) 1173 c->c_flags &= ~CALLOUT_ACTIVE; 1174 1175 if ((flags & CS_DRAIN) != 0) { 1176 /* 1177 * The current callout is running (or just 1178 * about to run) and blocking is allowed, so 1179 * just wait for the current invocation to 1180 * finish. 1181 */ 1182 if (cc_exec_curr(cc, direct) == c) { 1183 /* 1184 * Use direct calls to sleepqueue interface 1185 * instead of cv/msleep in order to avoid 1186 * a LOR between cc_lock and sleepqueue 1187 * chain spinlocks. This piece of code 1188 * emulates a msleep_spin() call actually. 1189 * 1190 * If we already have the sleepqueue chain 1191 * locked, then we can safely block. If we 1192 * don't already have it locked, however, 1193 * we have to drop the cc_lock to lock 1194 * it. This opens several races, so we 1195 * restart at the beginning once we have 1196 * both locks. If nothing has changed, then 1197 * we will end up back here with sq_locked 1198 * set. 1199 */ 1200 if (!sq_locked) { 1201 CC_UNLOCK(cc); 1202 sleepq_lock( 1203 &cc_exec_waiting(cc, direct)); 1204 sq_locked = 1; 1205 old_cc = cc; 1206 goto again; 1207 } 1208 1209 /* 1210 * Migration could be cancelled here, but 1211 * as long as it is still not sure when it 1212 * will be packed up, just let softclock() 1213 * take care of it. 1214 */ 1215 cc_exec_waiting(cc, direct) = true; 1216 DROP_GIANT(); 1217 CC_UNLOCK(cc); 1218 sleepq_add( 1219 &cc_exec_waiting(cc, direct), 1220 &cc->cc_lock.lock_object, "codrain", 1221 SLEEPQ_SLEEP, 0); 1222 sleepq_wait( 1223 &cc_exec_waiting(cc, direct), 1224 0); 1225 sq_locked = 0; 1226 old_cc = NULL; 1227 1228 /* Reacquire locks previously released. */ 1229 PICKUP_GIANT(); 1230 goto again; 1231 } 1232 c->c_flags &= ~CALLOUT_ACTIVE; 1233 } else if (use_lock && !cc_exec_cancel(cc, direct)) { 1234 1235 /* 1236 * The current callout is waiting for its 1237 * lock which we hold. Cancel the callout 1238 * and return. After our caller drops the 1239 * lock, the callout will be skipped in 1240 * softclock(). This *only* works with a 1241 * callout_stop() *not* with callout_drain(). 1242 */ 1243 cc_exec_cancel(cc, direct) = true; 1244 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 1245 c, c->c_func, c->c_arg); 1246 KASSERT(!cc_cce_migrating(cc, direct), 1247 ("callout wrongly scheduled for migration")); 1248 if (callout_migrating(c)) { 1249 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 1250 #ifdef SMP 1251 cc_migration_cpu(cc, direct) = CPUBLOCK; 1252 cc_migration_time(cc, direct) = 0; 1253 cc_migration_prec(cc, direct) = 0; 1254 cc_migration_func(cc, direct) = NULL; 1255 cc_migration_arg(cc, direct) = NULL; 1256 #endif 1257 } 1258 CC_UNLOCK(cc); 1259 KASSERT(!sq_locked, ("sleepqueue chain locked")); 1260 return (1); 1261 } else if (callout_migrating(c)) { 1262 /* 1263 * The callout is currently being serviced 1264 * and the "next" callout is scheduled at 1265 * its completion with a migration. We remove 1266 * the migration flag so it *won't* get rescheduled, 1267 * but we can't stop the one thats running so 1268 * we return 0. 1269 */ 1270 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 1271 #ifdef SMP 1272 /* 1273 * We can't call cc_cce_cleanup here since 1274 * if we do it will remove .ce_curr and 1275 * its still running. This will prevent a 1276 * reschedule of the callout when the 1277 * execution completes. 1278 */ 1279 cc_migration_cpu(cc, direct) = CPUBLOCK; 1280 cc_migration_time(cc, direct) = 0; 1281 cc_migration_prec(cc, direct) = 0; 1282 cc_migration_func(cc, direct) = NULL; 1283 cc_migration_arg(cc, direct) = NULL; 1284 #endif 1285 CTR3(KTR_CALLOUT, "postponing stop %p func %p arg %p", 1286 c, c->c_func, c->c_arg); 1287 CC_UNLOCK(cc); 1288 return (0); 1289 } else { 1290 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 1291 c, c->c_func, c->c_arg); 1292 } 1293 KASSERT(!sq_locked, ("sleepqueue chain still locked")); 1294 cancelled = 0; 1295 } else 1296 cancelled = 1; 1297 1298 if (sq_locked) 1299 sleepq_release(&cc_exec_waiting(cc, direct)); 1300 1301 if ((c->c_iflags & CALLOUT_PENDING) == 0) { 1302 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 1303 c, c->c_func, c->c_arg); 1304 /* 1305 * For not scheduled and not executing callout return 1306 * negative value. 1307 */ 1308 if (cc_exec_curr(cc, direct) != c) 1309 cancelled = -1; 1310 CC_UNLOCK(cc); 1311 return (cancelled); 1312 } 1313 1314 c->c_iflags &= ~CALLOUT_PENDING; 1315 c->c_flags &= ~CALLOUT_ACTIVE; 1316 1317 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 1318 c, c->c_func, c->c_arg); 1319 if (not_on_a_list == 0) { 1320 if ((c->c_iflags & CALLOUT_PROCESSED) == 0) { 1321 if (cc_exec_next(cc) == c) 1322 cc_exec_next(cc) = LIST_NEXT(c, c_links.le); 1323 LIST_REMOVE(c, c_links.le); 1324 } else { 1325 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe); 1326 } 1327 } 1328 CC_UNLOCK(cc); 1329 return (cancelled); 1330 } 1331 1332 void callout_init(struct callout * c,int mpsafe)1333 callout_init(struct callout *c, int mpsafe) 1334 { 1335 bzero(c, sizeof *c); 1336 if (mpsafe) { 1337 c->c_lock = NULL; 1338 c->c_iflags = CALLOUT_RETURNUNLOCKED; 1339 } else { 1340 c->c_lock = &Giant.lock_object; 1341 c->c_iflags = 0; 1342 } 1343 c->c_cpu = cc_default_cpu; 1344 } 1345 1346 void _callout_init_lock(struct callout * c,struct lock_object * lock,int flags)1347 _callout_init_lock(struct callout *c, struct lock_object *lock, int flags) 1348 { 1349 KASSERT(lock != NULL, ("%s: no lock", __func__)); 1350 KASSERT((flags & ~(CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK | 1351 CALLOUT_TRYLOCK)) == 0, 1352 ("%s: bad flags %d", __func__, flags)); 1353 KASSERT(!(LOCK_CLASS(lock)->lc_flags & LC_SLEEPABLE), 1354 ("%s: callout %p has sleepable lock", __func__, c)); 1355 KASSERT(!(flags & CALLOUT_TRYLOCK) || 1356 (LOCK_CLASS(lock)->lc_trylock != NULL), 1357 ("%s: CALLOUT_TRYLOCK requested for %s", 1358 __func__, LOCK_CLASS(lock)->lc_name)); 1359 1360 *c = (struct callout ){ 1361 .c_lock = lock, 1362 .c_iflags = flags, 1363 .c_cpu = cc_default_cpu, 1364 }; 1365 } 1366 1367 static int flssbt(sbintime_t sbt)1368 flssbt(sbintime_t sbt) 1369 { 1370 1371 sbt += (uint64_t)sbt >> 1; 1372 if (sizeof(long) >= sizeof(sbintime_t)) 1373 return (flsl(sbt)); 1374 if (sbt >= SBT_1S) 1375 return (flsl(((uint64_t)sbt) >> 32) + 32); 1376 return (flsl(sbt)); 1377 } 1378 1379 /* 1380 * Dump immediate statistic snapshot of the scheduled callouts. 1381 */ 1382 static int sysctl_kern_callout_stat(SYSCTL_HANDLER_ARGS)1383 sysctl_kern_callout_stat(SYSCTL_HANDLER_ARGS) 1384 { 1385 struct callout *tmp; 1386 struct callout_cpu *cc; 1387 struct callout_list *sc; 1388 sbintime_t maxpr, maxt, medpr, medt, now, spr, st, t; 1389 int ct[64], cpr[64], ccpbk[32]; 1390 int error, val, i, count, tcum, pcum, maxc, c, medc; 1391 int cpu; 1392 1393 val = 0; 1394 error = sysctl_handle_int(oidp, &val, 0, req); 1395 if (error != 0 || req->newptr == NULL) 1396 return (error); 1397 count = maxc = 0; 1398 st = spr = maxt = maxpr = 0; 1399 bzero(ccpbk, sizeof(ccpbk)); 1400 bzero(ct, sizeof(ct)); 1401 bzero(cpr, sizeof(cpr)); 1402 now = sbinuptime(); 1403 CPU_FOREACH(cpu) { 1404 cc = CC_CPU(cpu); 1405 CC_LOCK(cc); 1406 for (i = 0; i < callwheelsize; i++) { 1407 sc = &cc->cc_callwheel[i]; 1408 c = 0; 1409 LIST_FOREACH(tmp, sc, c_links.le) { 1410 c++; 1411 t = tmp->c_time - now; 1412 if (t < 0) 1413 t = 0; 1414 st += t / SBT_1US; 1415 spr += tmp->c_precision / SBT_1US; 1416 if (t > maxt) 1417 maxt = t; 1418 if (tmp->c_precision > maxpr) 1419 maxpr = tmp->c_precision; 1420 ct[flssbt(t)]++; 1421 cpr[flssbt(tmp->c_precision)]++; 1422 } 1423 if (c > maxc) 1424 maxc = c; 1425 ccpbk[fls(c + c / 2)]++; 1426 count += c; 1427 } 1428 CC_UNLOCK(cc); 1429 } 1430 1431 for (i = 0, tcum = 0; i < 64 && tcum < count / 2; i++) 1432 tcum += ct[i]; 1433 medt = (i >= 2) ? (((sbintime_t)1) << (i - 2)) : 0; 1434 for (i = 0, pcum = 0; i < 64 && pcum < count / 2; i++) 1435 pcum += cpr[i]; 1436 medpr = (i >= 2) ? (((sbintime_t)1) << (i - 2)) : 0; 1437 for (i = 0, c = 0; i < 32 && c < count / 2; i++) 1438 c += ccpbk[i]; 1439 medc = (i >= 2) ? (1 << (i - 2)) : 0; 1440 1441 printf("Scheduled callouts statistic snapshot:\n"); 1442 printf(" Callouts: %6d Buckets: %6d*%-3d Bucket size: 0.%06ds\n", 1443 count, callwheelsize, mp_ncpus, 1000000 >> CC_HASH_SHIFT); 1444 printf(" C/Bk: med %5d avg %6d.%06jd max %6d\n", 1445 medc, 1446 count / callwheelsize / mp_ncpus, 1447 (uint64_t)count * 1000000 / callwheelsize / mp_ncpus % 1000000, 1448 maxc); 1449 printf(" Time: med %5jd.%06jds avg %6jd.%06jds max %6jd.%06jds\n", 1450 medt / SBT_1S, (medt & 0xffffffff) * 1000000 >> 32, 1451 (st / count) / 1000000, (st / count) % 1000000, 1452 maxt / SBT_1S, (maxt & 0xffffffff) * 1000000 >> 32); 1453 printf(" Prec: med %5jd.%06jds avg %6jd.%06jds max %6jd.%06jds\n", 1454 medpr / SBT_1S, (medpr & 0xffffffff) * 1000000 >> 32, 1455 (spr / count) / 1000000, (spr / count) % 1000000, 1456 maxpr / SBT_1S, (maxpr & 0xffffffff) * 1000000 >> 32); 1457 printf(" Distribution: \tbuckets\t time\t tcum\t" 1458 " prec\t pcum\n"); 1459 for (i = 0, tcum = pcum = 0; i < 64; i++) { 1460 if (ct[i] == 0 && cpr[i] == 0) 1461 continue; 1462 t = (i != 0) ? (((sbintime_t)1) << (i - 1)) : 0; 1463 tcum += ct[i]; 1464 pcum += cpr[i]; 1465 printf(" %10jd.%06jds\t 2**%d\t%7d\t%7d\t%7d\t%7d\n", 1466 t / SBT_1S, (t & 0xffffffff) * 1000000 >> 32, 1467 i - 1 - (32 - CC_HASH_SHIFT), 1468 ct[i], tcum, cpr[i], pcum); 1469 } 1470 return (error); 1471 } 1472 SYSCTL_PROC(_kern, OID_AUTO, callout_stat, 1473 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, 1474 0, 0, sysctl_kern_callout_stat, "I", 1475 "Dump immediate statistic snapshot of the scheduled callouts"); 1476 1477 #ifdef DDB 1478 static void _show_callout(struct callout * c)1479 _show_callout(struct callout *c) 1480 { 1481 1482 db_printf("callout %p\n", c); 1483 #define C_DB_PRINTF(f, e) db_printf(" %s = " f "\n", #e, c->e); 1484 db_printf(" &c_links = %p\n", &(c->c_links)); 1485 C_DB_PRINTF("%" PRId64, c_time); 1486 C_DB_PRINTF("%" PRId64, c_precision); 1487 C_DB_PRINTF("%p", c_arg); 1488 C_DB_PRINTF("%p", c_func); 1489 C_DB_PRINTF("%p", c_lock); 1490 C_DB_PRINTF("%#x", c_flags); 1491 C_DB_PRINTF("%#x", c_iflags); 1492 C_DB_PRINTF("%d", c_cpu); 1493 #undef C_DB_PRINTF 1494 } 1495 DB_SHOW_COMMAND(callout,db_show_callout)1496 DB_SHOW_COMMAND(callout, db_show_callout) 1497 { 1498 1499 if (!have_addr) { 1500 db_printf("usage: show callout <struct callout *>\n"); 1501 return; 1502 } 1503 1504 _show_callout((struct callout *)addr); 1505 } 1506 1507 static void _show_last_callout(int cpu,int direct,const char * dirstr)1508 _show_last_callout(int cpu, int direct, const char *dirstr) 1509 { 1510 struct callout_cpu *cc; 1511 void *func, *arg; 1512 1513 cc = CC_CPU(cpu); 1514 func = cc_exec_last_func(cc, direct); 1515 arg = cc_exec_last_arg(cc, direct); 1516 db_printf("cpu %d last%s callout function: %p ", cpu, dirstr, func); 1517 db_printsym((db_expr_t)func, DB_STGY_ANY); 1518 db_printf("\ncpu %d last%s callout argument: %p\n", cpu, dirstr, arg); 1519 } 1520 DB_SHOW_COMMAND_FLAGS(callout_last,db_show_callout_last,DB_CMD_MEMSAFE)1521 DB_SHOW_COMMAND_FLAGS(callout_last, db_show_callout_last, DB_CMD_MEMSAFE) 1522 { 1523 int cpu, last; 1524 1525 if (have_addr) { 1526 if (addr < 0 || addr > mp_maxid || CPU_ABSENT(addr)) { 1527 db_printf("no such cpu: %d\n", (int)addr); 1528 return; 1529 } 1530 cpu = last = addr; 1531 } else { 1532 cpu = 0; 1533 last = mp_maxid; 1534 } 1535 1536 while (cpu <= last) { 1537 if (!CPU_ABSENT(cpu)) { 1538 _show_last_callout(cpu, 0, ""); 1539 _show_last_callout(cpu, 1, " direct"); 1540 } 1541 cpu++; 1542 } 1543 } 1544 #endif /* DDB */ 1545