Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/kern/kern_timeout.c
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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 * From: @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 37 */ 38 39 #include <sys/cdefs.h> 40 __FBSDID("$FreeBSD$"); 41 42 #include "opt_callout_profiling.h" 43 #include "opt_ddb.h" 44 #include "opt_rss.h" 45 46 #include <sys/param.h> 47 #include <sys/systm.h> 48 #include <sys/bus.h> 49 #include <sys/callout.h> 50 #include <sys/domainset.h> 51 #include <sys/file.h> 52 #include <sys/interrupt.h> 53 #include <sys/kernel.h> 54 #include <sys/ktr.h> 55 #include <sys/kthread.h> 56 #include <sys/lock.h> 57 #include <sys/malloc.h> 58 #include <sys/mutex.h> 59 #include <sys/proc.h> 60 #include <sys/random.h> 61 #include <sys/sched.h> 62 #include <sys/sdt.h> 63 #include <sys/sleepqueue.h> 64 #include <sys/sysctl.h> 65 #include <sys/smp.h> 66 #include <sys/unistd.h> 67 68 #ifdef DDB 69 #include <ddb/ddb.h> 70 #include <ddb/db_sym.h> 71 #include <machine/_inttypes.h> 72 #endif 73 74 #ifdef SMP 75 #include <machine/cpu.h> 76 #endif 77 78 DPCPU_DECLARE(sbintime_t, hardclocktime); 79 80 SDT_PROVIDER_DEFINE(callout_execute); 81 SDT_PROBE_DEFINE1(callout_execute, , , callout__start, "struct callout *"); 82 SDT_PROBE_DEFINE1(callout_execute, , , callout__end, "struct callout *"); 83 84 static void softclock_thread(void *arg); 85 86 #ifdef CALLOUT_PROFILING 87 static int avg_depth; 88 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0, 89 "Average number of items examined per softclock call. Units = 1/1000"); 90 static int avg_gcalls; 91 SYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0, 92 "Average number of Giant callouts made per softclock call. Units = 1/1000"); 93 static int avg_lockcalls; 94 SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls, CTLFLAG_RD, &avg_lockcalls, 0, 95 "Average number of lock callouts made per softclock call. Units = 1/1000"); 96 static int avg_mpcalls; 97 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0, 98 "Average number of MP callouts made per softclock call. Units = 1/1000"); 99 static int avg_depth_dir; 100 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth_dir, CTLFLAG_RD, &avg_depth_dir, 0, 101 "Average number of direct callouts examined per callout_process call. " 102 "Units = 1/1000"); 103 static int avg_lockcalls_dir; 104 SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls_dir, CTLFLAG_RD, 105 &avg_lockcalls_dir, 0, "Average number of lock direct callouts made per " 106 "callout_process call. Units = 1/1000"); 107 static int avg_mpcalls_dir; 108 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls_dir, CTLFLAG_RD, &avg_mpcalls_dir, 109 0, "Average number of MP direct callouts made per callout_process call. " 110 "Units = 1/1000"); 111 #endif 112 113 static int ncallout; 114 SYSCTL_INT(_kern, OID_AUTO, ncallout, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &ncallout, 0, 115 "Number of entries in callwheel and size of timeout() preallocation"); 116 117 #ifdef RSS 118 static int pin_default_swi = 1; 119 static int pin_pcpu_swi = 1; 120 #else 121 static int pin_default_swi = 0; 122 static int pin_pcpu_swi = 0; 123 #endif 124 125 SYSCTL_INT(_kern, OID_AUTO, pin_default_swi, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &pin_default_swi, 126 0, "Pin the default (non-per-cpu) swi (shared with PCPU 0 swi)"); 127 SYSCTL_INT(_kern, OID_AUTO, pin_pcpu_swi, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &pin_pcpu_swi, 128 0, "Pin the per-CPU swis (except PCPU 0, which is also default)"); 129 130 /* 131 * TODO: 132 * allocate more timeout table slots when table overflows. 133 */ 134 static u_int __read_mostly callwheelsize; 135 static u_int __read_mostly callwheelmask; 136 137 /* 138 * The callout cpu exec entities represent informations necessary for 139 * describing the state of callouts currently running on the CPU and the ones 140 * necessary for migrating callouts to the new callout cpu. In particular, 141 * the first entry of the array cc_exec_entity holds informations for callout 142 * running in SWI thread context, while the second one holds informations 143 * for callout running directly from hardware interrupt context. 144 * The cached informations are very important for deferring migration when 145 * the migrating callout is already running. 146 */ 147 struct cc_exec { 148 struct callout *cc_curr; 149 callout_func_t *cc_drain; 150 void *cc_last_func; 151 void *cc_last_arg; 152 #ifdef SMP 153 callout_func_t *ce_migration_func; 154 void *ce_migration_arg; 155 sbintime_t ce_migration_time; 156 sbintime_t ce_migration_prec; 157 int ce_migration_cpu; 158 #endif 159 bool cc_cancel; 160 bool cc_waiting; 161 }; 162 163 /* 164 * There is one struct callout_cpu per cpu, holding all relevant 165 * state for the callout processing thread on the individual CPU. 166 */ 167 struct callout_cpu { 168 struct mtx_padalign cc_lock; 169 struct cc_exec cc_exec_entity[2]; 170 struct callout *cc_next; 171 struct callout_list *cc_callwheel; 172 struct callout_tailq cc_expireq; 173 sbintime_t cc_firstevent; 174 sbintime_t cc_lastscan; 175 struct thread *cc_thread; 176 u_int cc_bucket; 177 #ifdef KTR 178 char cc_ktr_event_name[20]; 179 #endif 180 }; 181 182 #define callout_migrating(c) ((c)->c_iflags & CALLOUT_DFRMIGRATION) 183 184 #define cc_exec_curr(cc, dir) cc->cc_exec_entity[dir].cc_curr 185 #define cc_exec_last_func(cc, dir) cc->cc_exec_entity[dir].cc_last_func 186 #define cc_exec_last_arg(cc, dir) cc->cc_exec_entity[dir].cc_last_arg 187 #define cc_exec_drain(cc, dir) cc->cc_exec_entity[dir].cc_drain 188 #define cc_exec_next(cc) cc->cc_next 189 #define cc_exec_cancel(cc, dir) cc->cc_exec_entity[dir].cc_cancel 190 #define cc_exec_waiting(cc, dir) cc->cc_exec_entity[dir].cc_waiting 191 #ifdef SMP 192 #define cc_migration_func(cc, dir) cc->cc_exec_entity[dir].ce_migration_func 193 #define cc_migration_arg(cc, dir) cc->cc_exec_entity[dir].ce_migration_arg 194 #define cc_migration_cpu(cc, dir) cc->cc_exec_entity[dir].ce_migration_cpu 195 #define cc_migration_time(cc, dir) cc->cc_exec_entity[dir].ce_migration_time 196 #define cc_migration_prec(cc, dir) cc->cc_exec_entity[dir].ce_migration_prec 197 198 static struct callout_cpu cc_cpu[MAXCPU]; 199 #define CPUBLOCK MAXCPU 200 #define CC_CPU(cpu) (&cc_cpu[(cpu)]) 201 #define CC_SELF() CC_CPU(PCPU_GET(cpuid)) 202 #else 203 static struct callout_cpu cc_cpu; 204 #define CC_CPU(cpu) (&cc_cpu) 205 #define CC_SELF() (&cc_cpu) 206 #endif 207 #define CC_LOCK(cc) mtx_lock_spin(&(cc)->cc_lock) 208 #define CC_UNLOCK(cc) mtx_unlock_spin(&(cc)->cc_lock) 209 #define CC_LOCK_ASSERT(cc) mtx_assert(&(cc)->cc_lock, MA_OWNED) 210 211 static int __read_mostly cc_default_cpu; 212 213 static void callout_cpu_init(struct callout_cpu *cc, int cpu); 214 static void softclock_call_cc(struct callout *c, struct callout_cpu *cc, 215 #ifdef CALLOUT_PROFILING 216 int *mpcalls, int *lockcalls, int *gcalls, 217 #endif 218 int direct); 219 220 static MALLOC_DEFINE(M_CALLOUT, "callout", "Callout datastructures"); 221 222 /** 223 * Locked by cc_lock: 224 * cc_curr - If a callout is in progress, it is cc_curr. 225 * If cc_curr is non-NULL, threads waiting in 226 * callout_drain() will be woken up as soon as the 227 * relevant callout completes. 228 * cc_cancel - Changing to 1 with both callout_lock and cc_lock held 229 * guarantees that the current callout will not run. 230 * The softclock_call_cc() function sets this to 0 before it 231 * drops callout_lock to acquire c_lock, and it calls 232 * the handler only if curr_cancelled is still 0 after 233 * cc_lock is successfully acquired. 234 * cc_waiting - If a thread is waiting in callout_drain(), then 235 * callout_wait is nonzero. Set only when 236 * cc_curr is non-NULL. 237 */ 238 239 /* 240 * Resets the execution entity tied to a specific callout cpu. 241 */ 242 static void 243 cc_cce_cleanup(struct callout_cpu *cc, int direct) 244 { 245 246 cc_exec_curr(cc, direct) = NULL; 247 cc_exec_cancel(cc, direct) = false; 248 cc_exec_waiting(cc, direct) = false; 249 #ifdef SMP 250 cc_migration_cpu(cc, direct) = CPUBLOCK; 251 cc_migration_time(cc, direct) = 0; 252 cc_migration_prec(cc, direct) = 0; 253 cc_migration_func(cc, direct) = NULL; 254 cc_migration_arg(cc, direct) = NULL; 255 #endif 256 } 257 258 /* 259 * Checks if migration is requested by a specific callout cpu. 260 */ 261 static int 262 cc_cce_migrating(struct callout_cpu *cc, int direct) 263 { 264 265 #ifdef SMP 266 return (cc_migration_cpu(cc, direct) != CPUBLOCK); 267 #else 268 return (0); 269 #endif 270 } 271 272 /* 273 * Kernel low level callwheel initialization 274 * called on the BSP during kernel startup. 275 */ 276 static void 277 callout_callwheel_init(void *dummy) 278 { 279 struct callout_cpu *cc; 280 int cpu; 281 282 /* 283 * Calculate the size of the callout wheel and the preallocated 284 * timeout() structures. 285 * XXX: Clip callout to result of previous function of maxusers 286 * maximum 384. This is still huge, but acceptable. 287 */ 288 ncallout = imin(16 + maxproc + maxfiles, 18508); 289 TUNABLE_INT_FETCH("kern.ncallout", &ncallout); 290 291 /* 292 * Calculate callout wheel size, should be next power of two higher 293 * than 'ncallout'. 294 */ 295 callwheelsize = 1 << fls(ncallout); 296 callwheelmask = callwheelsize - 1; 297 298 /* 299 * Fetch whether we're pinning the swi's or not. 300 */ 301 TUNABLE_INT_FETCH("kern.pin_default_swi", &pin_default_swi); 302 TUNABLE_INT_FETCH("kern.pin_pcpu_swi", &pin_pcpu_swi); 303 304 /* 305 * Initialize callout wheels. The software interrupt threads 306 * are created later. 307 */ 308 cc_default_cpu = PCPU_GET(cpuid); 309 CPU_FOREACH(cpu) { 310 cc = CC_CPU(cpu); 311 callout_cpu_init(cc, cpu); 312 } 313 } 314 SYSINIT(callwheel_init, SI_SUB_CPU, SI_ORDER_ANY, callout_callwheel_init, NULL); 315 316 /* 317 * Initialize the per-cpu callout structures. 318 */ 319 static void 320 callout_cpu_init(struct callout_cpu *cc, int cpu) 321 { 322 int i; 323 324 mtx_init(&cc->cc_lock, "callout", NULL, MTX_SPIN); 325 cc->cc_callwheel = malloc_domainset(sizeof(struct callout_list) * 326 callwheelsize, M_CALLOUT, 327 DOMAINSET_PREF(pcpu_find(cpu)->pc_domain), M_WAITOK); 328 for (i = 0; i < callwheelsize; i++) 329 LIST_INIT(&cc->cc_callwheel[i]); 330 TAILQ_INIT(&cc->cc_expireq); 331 cc->cc_firstevent = SBT_MAX; 332 for (i = 0; i < 2; i++) 333 cc_cce_cleanup(cc, i); 334 #ifdef KTR 335 snprintf(cc->cc_ktr_event_name, sizeof(cc->cc_ktr_event_name), 336 "callwheel cpu %d", cpu); 337 #endif 338 } 339 340 #ifdef SMP 341 /* 342 * Switches the cpu tied to a specific callout. 343 * The function expects a locked incoming callout cpu and returns with 344 * locked outcoming callout cpu. 345 */ 346 static struct callout_cpu * 347 callout_cpu_switch(struct callout *c, struct callout_cpu *cc, int new_cpu) 348 { 349 struct callout_cpu *new_cc; 350 351 MPASS(c != NULL && cc != NULL); 352 CC_LOCK_ASSERT(cc); 353 354 /* 355 * Avoid interrupts and preemption firing after the callout cpu 356 * is blocked in order to avoid deadlocks as the new thread 357 * may be willing to acquire the callout cpu lock. 358 */ 359 c->c_cpu = CPUBLOCK; 360 spinlock_enter(); 361 CC_UNLOCK(cc); 362 new_cc = CC_CPU(new_cpu); 363 CC_LOCK(new_cc); 364 spinlock_exit(); 365 c->c_cpu = new_cpu; 366 return (new_cc); 367 } 368 #endif 369 370 /* 371 * Start softclock threads. 372 */ 373 static void 374 start_softclock(void *dummy) 375 { 376 struct proc *p; 377 struct thread *td; 378 struct callout_cpu *cc; 379 int cpu, error; 380 bool pin_swi; 381 382 p = NULL; 383 CPU_FOREACH(cpu) { 384 cc = CC_CPU(cpu); 385 error = kproc_kthread_add(softclock_thread, cc, &p, &td, 386 RFSTOPPED, 0, "clock", "clock (%d)", cpu); 387 if (error != 0) 388 panic("failed to create softclock thread for cpu %d: %d", 389 cpu, error); 390 CC_LOCK(cc); 391 cc->cc_thread = td; 392 thread_lock(td); 393 sched_class(td, PRI_ITHD); 394 sched_ithread_prio(td, PI_SOFTCLOCK); 395 TD_SET_IWAIT(td); 396 thread_lock_set(td, (struct mtx *)&cc->cc_lock); 397 thread_unlock(td); 398 if (cpu == cc_default_cpu) 399 pin_swi = pin_default_swi; 400 else 401 pin_swi = pin_pcpu_swi; 402 if (pin_swi) { 403 error = cpuset_setithread(td->td_tid, cpu); 404 if (error != 0) 405 printf("%s: %s clock couldn't be pinned to cpu %d: %d\n", 406 __func__, cpu == cc_default_cpu ? 407 "default" : "per-cpu", cpu, error); 408 } 409 } 410 } 411 SYSINIT(start_softclock, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_softclock, NULL); 412 413 #define CC_HASH_SHIFT 8 414 415 static inline u_int 416 callout_hash(sbintime_t sbt) 417 { 418 419 return (sbt >> (32 - CC_HASH_SHIFT)); 420 } 421 422 static inline u_int 423 callout_get_bucket(sbintime_t sbt) 424 { 425 426 return (callout_hash(sbt) & callwheelmask); 427 } 428 429 void 430 callout_process(sbintime_t now) 431 { 432 struct callout_entropy { 433 struct callout_cpu *cc; 434 struct thread *td; 435 sbintime_t now; 436 } entropy; 437 struct callout *c, *next; 438 struct callout_cpu *cc; 439 struct callout_list *sc; 440 struct thread *td; 441 sbintime_t first, last, lookahead, max, tmp_max; 442 u_int firstb, lastb, nowb; 443 #ifdef CALLOUT_PROFILING 444 int depth_dir = 0, mpcalls_dir = 0, lockcalls_dir = 0; 445 #endif 446 447 cc = CC_SELF(); 448 mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET); 449 450 /* Compute the buckets of the last scan and present times. */ 451 firstb = callout_hash(cc->cc_lastscan); 452 cc->cc_lastscan = now; 453 nowb = callout_hash(now); 454 455 /* Compute the last bucket and minimum time of the bucket after it. */ 456 if (nowb == firstb) 457 lookahead = (SBT_1S / 16); 458 else if (nowb - firstb == 1) 459 lookahead = (SBT_1S / 8); 460 else 461 lookahead = SBT_1S; 462 first = last = now; 463 first += (lookahead / 2); 464 last += lookahead; 465 last &= (0xffffffffffffffffLLU << (32 - CC_HASH_SHIFT)); 466 lastb = callout_hash(last) - 1; 467 max = last; 468 469 /* 470 * Check if we wrapped around the entire wheel from the last scan. 471 * In case, we need to scan entirely the wheel for pending callouts. 472 */ 473 if (lastb - firstb >= callwheelsize) { 474 lastb = firstb + callwheelsize - 1; 475 if (nowb - firstb >= callwheelsize) 476 nowb = lastb; 477 } 478 479 /* Iterate callwheel from firstb to nowb and then up to lastb. */ 480 do { 481 sc = &cc->cc_callwheel[firstb & callwheelmask]; 482 LIST_FOREACH_SAFE(c, sc, c_links.le, next) { 483 /* Run the callout if present time within allowed. */ 484 if (c->c_time <= now) { 485 /* 486 * Consumer told us the callout may be run 487 * directly from hardware interrupt context. 488 */ 489 if (c->c_iflags & CALLOUT_DIRECT) { 490 #ifdef CALLOUT_PROFILING 491 ++depth_dir; 492 #endif 493 cc_exec_next(cc) = next; 494 cc->cc_bucket = firstb & callwheelmask; 495 LIST_REMOVE(c, c_links.le); 496 softclock_call_cc(c, cc, 497 #ifdef CALLOUT_PROFILING 498 &mpcalls_dir, &lockcalls_dir, NULL, 499 #endif 500 1); 501 next = cc_exec_next(cc); 502 cc_exec_next(cc) = NULL; 503 } else { 504 LIST_REMOVE(c, c_links.le); 505 TAILQ_INSERT_TAIL(&cc->cc_expireq, 506 c, c_links.tqe); 507 c->c_iflags |= CALLOUT_PROCESSED; 508 } 509 } else if (c->c_time >= max) { 510 /* 511 * Skip events in the distant future. 512 */ 513 ; 514 } else if (c->c_time > last) { 515 /* 516 * Event minimal time is bigger than present 517 * maximal time, so it cannot be aggregated. 518 */ 519 lastb = nowb; 520 } else { 521 /* 522 * Update first and last time, respecting this 523 * event. 524 */ 525 if (c->c_time < first) 526 first = c->c_time; 527 tmp_max = c->c_time + c->c_precision; 528 if (tmp_max < last) 529 last = tmp_max; 530 } 531 } 532 /* Proceed with the next bucket. */ 533 firstb++; 534 /* 535 * Stop if we looked after present time and found 536 * some event we can't execute at now. 537 * Stop if we looked far enough into the future. 538 */ 539 } while (((int)(firstb - lastb)) <= 0); 540 cc->cc_firstevent = last; 541 cpu_new_callout(curcpu, last, first); 542 543 #ifdef CALLOUT_PROFILING 544 avg_depth_dir += (depth_dir * 1000 - avg_depth_dir) >> 8; 545 avg_mpcalls_dir += (mpcalls_dir * 1000 - avg_mpcalls_dir) >> 8; 546 avg_lockcalls_dir += (lockcalls_dir * 1000 - avg_lockcalls_dir) >> 8; 547 #endif 548 if (!TAILQ_EMPTY(&cc->cc_expireq)) { 549 entropy.cc = cc; 550 entropy.td = curthread; 551 entropy.now = now; 552 random_harvest_queue(&entropy, sizeof(entropy), RANDOM_CALLOUT); 553 554 td = cc->cc_thread; 555 if (TD_AWAITING_INTR(td)) { 556 thread_lock_block_wait(td); 557 THREAD_LOCK_ASSERT(td, MA_OWNED); 558 TD_CLR_IWAIT(td); 559 sched_wakeup(td, SRQ_INTR); 560 } else 561 mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET); 562 } else 563 mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET); 564 } 565 566 static struct callout_cpu * 567 callout_lock(struct callout *c) 568 { 569 struct callout_cpu *cc; 570 int cpu; 571 572 for (;;) { 573 cpu = c->c_cpu; 574 #ifdef SMP 575 if (cpu == CPUBLOCK) { 576 while (c->c_cpu == CPUBLOCK) 577 cpu_spinwait(); 578 continue; 579 } 580 #endif 581 cc = CC_CPU(cpu); 582 CC_LOCK(cc); 583 if (cpu == c->c_cpu) 584 break; 585 CC_UNLOCK(cc); 586 } 587 return (cc); 588 } 589 590 static void 591 callout_cc_add(struct callout *c, struct callout_cpu *cc, 592 sbintime_t sbt, sbintime_t precision, void (*func)(void *), 593 void *arg, int flags) 594 { 595 int bucket; 596 597 CC_LOCK_ASSERT(cc); 598 if (sbt < cc->cc_lastscan) 599 sbt = cc->cc_lastscan; 600 c->c_arg = arg; 601 c->c_iflags |= CALLOUT_PENDING; 602 c->c_iflags &= ~CALLOUT_PROCESSED; 603 c->c_flags |= CALLOUT_ACTIVE; 604 if (flags & C_DIRECT_EXEC) 605 c->c_iflags |= CALLOUT_DIRECT; 606 c->c_func = func; 607 c->c_time = sbt; 608 c->c_precision = precision; 609 bucket = callout_get_bucket(c->c_time); 610 CTR3(KTR_CALLOUT, "precision set for %p: %d.%08x", 611 c, (int)(c->c_precision >> 32), 612 (u_int)(c->c_precision & 0xffffffff)); 613 LIST_INSERT_HEAD(&cc->cc_callwheel[bucket], c, c_links.le); 614 if (cc->cc_bucket == bucket) 615 cc_exec_next(cc) = c; 616 617 /* 618 * Inform the eventtimers(4) subsystem there's a new callout 619 * that has been inserted, but only if really required. 620 */ 621 if (SBT_MAX - c->c_time < c->c_precision) 622 c->c_precision = SBT_MAX - c->c_time; 623 sbt = c->c_time + c->c_precision; 624 if (sbt < cc->cc_firstevent) { 625 cc->cc_firstevent = sbt; 626 cpu_new_callout(c->c_cpu, sbt, c->c_time); 627 } 628 } 629 630 static void 631 softclock_call_cc(struct callout *c, struct callout_cpu *cc, 632 #ifdef CALLOUT_PROFILING 633 int *mpcalls, int *lockcalls, int *gcalls, 634 #endif 635 int direct) 636 { 637 struct rm_priotracker tracker; 638 callout_func_t *c_func, *drain; 639 void *c_arg; 640 struct lock_class *class; 641 struct lock_object *c_lock; 642 uintptr_t lock_status; 643 int c_iflags; 644 #ifdef SMP 645 struct callout_cpu *new_cc; 646 callout_func_t *new_func; 647 void *new_arg; 648 int flags, new_cpu; 649 sbintime_t new_prec, new_time; 650 #endif 651 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING) 652 sbintime_t sbt1, sbt2; 653 struct timespec ts2; 654 static sbintime_t maxdt = 2 * SBT_1MS; /* 2 msec */ 655 static callout_func_t *lastfunc; 656 #endif 657 658 KASSERT((c->c_iflags & CALLOUT_PENDING) == CALLOUT_PENDING, 659 ("softclock_call_cc: pend %p %x", c, c->c_iflags)); 660 KASSERT((c->c_flags & CALLOUT_ACTIVE) == CALLOUT_ACTIVE, 661 ("softclock_call_cc: act %p %x", c, c->c_flags)); 662 class = (c->c_lock != NULL) ? LOCK_CLASS(c->c_lock) : NULL; 663 lock_status = 0; 664 if (c->c_iflags & CALLOUT_SHAREDLOCK) { 665 if (class == &lock_class_rm) 666 lock_status = (uintptr_t)&tracker; 667 else 668 lock_status = 1; 669 } 670 c_lock = c->c_lock; 671 c_func = c->c_func; 672 c_arg = c->c_arg; 673 c_iflags = c->c_iflags; 674 c->c_iflags &= ~CALLOUT_PENDING; 675 676 cc_exec_curr(cc, direct) = c; 677 cc_exec_last_func(cc, direct) = c_func; 678 cc_exec_last_arg(cc, direct) = c_arg; 679 cc_exec_cancel(cc, direct) = false; 680 cc_exec_drain(cc, direct) = NULL; 681 CC_UNLOCK(cc); 682 if (c_lock != NULL) { 683 class->lc_lock(c_lock, lock_status); 684 /* 685 * The callout may have been cancelled 686 * while we switched locks. 687 */ 688 if (cc_exec_cancel(cc, direct)) { 689 class->lc_unlock(c_lock); 690 goto skip; 691 } 692 /* The callout cannot be stopped now. */ 693 cc_exec_cancel(cc, direct) = true; 694 if (c_lock == &Giant.lock_object) { 695 #ifdef CALLOUT_PROFILING 696 (*gcalls)++; 697 #endif 698 CTR3(KTR_CALLOUT, "callout giant %p func %p arg %p", 699 c, c_func, c_arg); 700 } else { 701 #ifdef CALLOUT_PROFILING 702 (*lockcalls)++; 703 #endif 704 CTR3(KTR_CALLOUT, "callout lock %p func %p arg %p", 705 c, c_func, c_arg); 706 } 707 } else { 708 #ifdef CALLOUT_PROFILING 709 (*mpcalls)++; 710 #endif 711 CTR3(KTR_CALLOUT, "callout %p func %p arg %p", 712 c, c_func, c_arg); 713 } 714 KTR_STATE3(KTR_SCHED, "callout", cc->cc_ktr_event_name, "running", 715 "func:%p", c_func, "arg:%p", c_arg, "direct:%d", direct); 716 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING) 717 sbt1 = sbinuptime(); 718 #endif 719 THREAD_NO_SLEEPING(); 720 SDT_PROBE1(callout_execute, , , callout__start, c); 721 c_func(c_arg); 722 SDT_PROBE1(callout_execute, , , callout__end, c); 723 THREAD_SLEEPING_OK(); 724 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING) 725 sbt2 = sbinuptime(); 726 sbt2 -= sbt1; 727 if (sbt2 > maxdt) { 728 if (lastfunc != c_func || sbt2 > maxdt * 2) { 729 ts2 = sbttots(sbt2); 730 printf( 731 "Expensive timeout(9) function: %p(%p) %jd.%09ld s\n", 732 c_func, c_arg, (intmax_t)ts2.tv_sec, ts2.tv_nsec); 733 } 734 maxdt = sbt2; 735 lastfunc = c_func; 736 } 737 #endif 738 KTR_STATE0(KTR_SCHED, "callout", cc->cc_ktr_event_name, "idle"); 739 CTR1(KTR_CALLOUT, "callout %p finished", c); 740 if ((c_iflags & CALLOUT_RETURNUNLOCKED) == 0) 741 class->lc_unlock(c_lock); 742 skip: 743 CC_LOCK(cc); 744 KASSERT(cc_exec_curr(cc, direct) == c, ("mishandled cc_curr")); 745 cc_exec_curr(cc, direct) = NULL; 746 if (cc_exec_drain(cc, direct)) { 747 drain = cc_exec_drain(cc, direct); 748 cc_exec_drain(cc, direct) = NULL; 749 CC_UNLOCK(cc); 750 drain(c_arg); 751 CC_LOCK(cc); 752 } 753 if (cc_exec_waiting(cc, direct)) { 754 /* 755 * There is someone waiting for the 756 * callout to complete. 757 * If the callout was scheduled for 758 * migration just cancel it. 759 */ 760 if (cc_cce_migrating(cc, direct)) { 761 cc_cce_cleanup(cc, direct); 762 763 /* 764 * It should be assert here that the callout is not 765 * destroyed but that is not easy. 766 */ 767 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 768 } 769 cc_exec_waiting(cc, direct) = false; 770 CC_UNLOCK(cc); 771 wakeup(&cc_exec_waiting(cc, direct)); 772 CC_LOCK(cc); 773 } else if (cc_cce_migrating(cc, direct)) { 774 #ifdef SMP 775 /* 776 * If the callout was scheduled for 777 * migration just perform it now. 778 */ 779 new_cpu = cc_migration_cpu(cc, direct); 780 new_time = cc_migration_time(cc, direct); 781 new_prec = cc_migration_prec(cc, direct); 782 new_func = cc_migration_func(cc, direct); 783 new_arg = cc_migration_arg(cc, direct); 784 cc_cce_cleanup(cc, direct); 785 786 /* 787 * It should be assert here that the callout is not destroyed 788 * but that is not easy. 789 * 790 * As first thing, handle deferred callout stops. 791 */ 792 if (!callout_migrating(c)) { 793 CTR3(KTR_CALLOUT, 794 "deferred cancelled %p func %p arg %p", 795 c, new_func, new_arg); 796 return; 797 } 798 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 799 800 new_cc = callout_cpu_switch(c, cc, new_cpu); 801 flags = (direct) ? C_DIRECT_EXEC : 0; 802 callout_cc_add(c, new_cc, new_time, new_prec, new_func, 803 new_arg, flags); 804 CC_UNLOCK(new_cc); 805 CC_LOCK(cc); 806 #else 807 panic("migration should not happen"); 808 #endif 809 } 810 } 811 812 /* 813 * The callout mechanism is based on the work of Adam M. Costello and 814 * George Varghese, published in a technical report entitled "Redesigning 815 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 816 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 817 * used in this implementation was published by G. Varghese and T. Lauck in 818 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 819 * the Efficient Implementation of a Timer Facility" in the Proceedings of 820 * the 11th ACM Annual Symposium on Operating Systems Principles, 821 * Austin, Texas Nov 1987. 822 */ 823 824 /* 825 * Software (low priority) clock interrupt thread handler. 826 * Run periodic events from timeout queue. 827 */ 828 static void 829 softclock_thread(void *arg) 830 { 831 struct thread *td = curthread; 832 struct callout_cpu *cc; 833 struct callout *c; 834 #ifdef CALLOUT_PROFILING 835 int depth, gcalls, lockcalls, mpcalls; 836 #endif 837 838 cc = (struct callout_cpu *)arg; 839 CC_LOCK(cc); 840 for (;;) { 841 while (TAILQ_EMPTY(&cc->cc_expireq)) { 842 /* 843 * Use CC_LOCK(cc) as the thread_lock while 844 * idle. 845 */ 846 thread_lock(td); 847 thread_lock_set(td, (struct mtx *)&cc->cc_lock); 848 TD_SET_IWAIT(td); 849 mi_switch(SW_VOL | SWT_IWAIT); 850 851 /* mi_switch() drops thread_lock(). */ 852 CC_LOCK(cc); 853 } 854 855 #ifdef CALLOUT_PROFILING 856 depth = gcalls = lockcalls = mpcalls = 0; 857 #endif 858 while ((c = TAILQ_FIRST(&cc->cc_expireq)) != NULL) { 859 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe); 860 softclock_call_cc(c, cc, 861 #ifdef CALLOUT_PROFILING 862 &mpcalls, &lockcalls, &gcalls, 863 #endif 864 0); 865 #ifdef CALLOUT_PROFILING 866 ++depth; 867 #endif 868 } 869 #ifdef CALLOUT_PROFILING 870 avg_depth += (depth * 1000 - avg_depth) >> 8; 871 avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8; 872 avg_lockcalls += (lockcalls * 1000 - avg_lockcalls) >> 8; 873 avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8; 874 #endif 875 } 876 } 877 878 void 879 callout_when(sbintime_t sbt, sbintime_t precision, int flags, 880 sbintime_t *res, sbintime_t *prec_res) 881 { 882 sbintime_t to_sbt, to_pr; 883 884 if ((flags & (C_ABSOLUTE | C_PRECALC)) != 0) { 885 *res = sbt; 886 *prec_res = precision; 887 return; 888 } 889 if ((flags & C_HARDCLOCK) != 0 && sbt < tick_sbt) 890 sbt = tick_sbt; 891 if ((flags & C_HARDCLOCK) != 0 || sbt >= sbt_tickthreshold) { 892 /* 893 * Obtain the time of the last hardclock() call on 894 * this CPU directly from the kern_clocksource.c. 895 * This value is per-CPU, but it is equal for all 896 * active ones. 897 */ 898 #ifdef __LP64__ 899 to_sbt = DPCPU_GET(hardclocktime); 900 #else 901 spinlock_enter(); 902 to_sbt = DPCPU_GET(hardclocktime); 903 spinlock_exit(); 904 #endif 905 if (cold && to_sbt == 0) 906 to_sbt = sbinuptime(); 907 if ((flags & C_HARDCLOCK) == 0) 908 to_sbt += tick_sbt; 909 } else 910 to_sbt = sbinuptime(); 911 if (SBT_MAX - to_sbt < sbt) 912 to_sbt = SBT_MAX; 913 else 914 to_sbt += sbt; 915 *res = to_sbt; 916 to_pr = ((C_PRELGET(flags) < 0) ? sbt >> tc_precexp : 917 sbt >> C_PRELGET(flags)); 918 *prec_res = to_pr > precision ? to_pr : precision; 919 } 920 921 /* 922 * New interface; clients allocate their own callout structures. 923 * 924 * callout_reset() - establish or change a timeout 925 * callout_stop() - disestablish a timeout 926 * callout_init() - initialize a callout structure so that it can 927 * safely be passed to callout_reset() and callout_stop() 928 * 929 * <sys/callout.h> defines three convenience macros: 930 * 931 * callout_active() - returns truth if callout has not been stopped, 932 * drained, or deactivated since the last time the callout was 933 * reset. 934 * callout_pending() - returns truth if callout is still waiting for timeout 935 * callout_deactivate() - marks the callout as having been serviced 936 */ 937 int 938 callout_reset_sbt_on(struct callout *c, sbintime_t sbt, sbintime_t prec, 939 callout_func_t *ftn, void *arg, int cpu, int flags) 940 { 941 sbintime_t to_sbt, precision; 942 struct callout_cpu *cc; 943 int cancelled, direct; 944 945 cancelled = 0; 946 callout_when(sbt, prec, flags, &to_sbt, &precision); 947 948 /* 949 * This flag used to be added by callout_cc_add, but the 950 * first time you call this we could end up with the 951 * wrong direct flag if we don't do it before we add. 952 */ 953 if (flags & C_DIRECT_EXEC) { 954 direct = 1; 955 } else { 956 direct = 0; 957 } 958 KASSERT(!direct || c->c_lock == NULL || 959 (LOCK_CLASS(c->c_lock)->lc_flags & LC_SPINLOCK), 960 ("%s: direct callout %p has non-spin lock", __func__, c)); 961 962 cc = callout_lock(c); 963 if (cpu == -1) 964 cpu = c->c_cpu; 965 KASSERT(cpu >= 0 && cpu <= mp_maxid && !CPU_ABSENT(cpu), 966 ("%s: invalid cpu %d", __func__, cpu)); 967 968 if (cc_exec_curr(cc, direct) == c) { 969 /* 970 * We're being asked to reschedule a callout which is 971 * currently in progress. If there is a lock then we 972 * can cancel the callout if it has not really started. 973 */ 974 if (c->c_lock != NULL && !cc_exec_cancel(cc, direct)) 975 cancelled = cc_exec_cancel(cc, direct) = true; 976 if (cc_exec_waiting(cc, direct) || cc_exec_drain(cc, direct)) { 977 /* 978 * Someone has called callout_drain to kill this 979 * callout. Don't reschedule. 980 */ 981 CTR4(KTR_CALLOUT, "%s %p func %p arg %p", 982 cancelled ? "cancelled" : "failed to cancel", 983 c, c->c_func, c->c_arg); 984 CC_UNLOCK(cc); 985 return (cancelled); 986 } 987 #ifdef SMP 988 if (callout_migrating(c)) { 989 /* 990 * This only occurs when a second callout_reset_sbt_on 991 * is made after a previous one moved it into 992 * deferred migration (below). Note we do *not* change 993 * the prev_cpu even though the previous target may 994 * be different. 995 */ 996 cc_migration_cpu(cc, direct) = cpu; 997 cc_migration_time(cc, direct) = to_sbt; 998 cc_migration_prec(cc, direct) = precision; 999 cc_migration_func(cc, direct) = ftn; 1000 cc_migration_arg(cc, direct) = arg; 1001 cancelled = 1; 1002 CC_UNLOCK(cc); 1003 return (cancelled); 1004 } 1005 #endif 1006 } 1007 if (c->c_iflags & CALLOUT_PENDING) { 1008 if ((c->c_iflags & CALLOUT_PROCESSED) == 0) { 1009 if (cc_exec_next(cc) == c) 1010 cc_exec_next(cc) = LIST_NEXT(c, c_links.le); 1011 LIST_REMOVE(c, c_links.le); 1012 } else { 1013 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe); 1014 } 1015 cancelled = 1; 1016 c->c_iflags &= ~ CALLOUT_PENDING; 1017 c->c_flags &= ~ CALLOUT_ACTIVE; 1018 } 1019 1020 #ifdef SMP 1021 /* 1022 * If the callout must migrate try to perform it immediately. 1023 * If the callout is currently running, just defer the migration 1024 * to a more appropriate moment. 1025 */ 1026 if (c->c_cpu != cpu) { 1027 if (cc_exec_curr(cc, direct) == c) { 1028 /* 1029 * Pending will have been removed since we are 1030 * actually executing the callout on another 1031 * CPU. That callout should be waiting on the 1032 * lock the caller holds. If we set both 1033 * active/and/pending after we return and the 1034 * lock on the executing callout proceeds, it 1035 * will then see pending is true and return. 1036 * At the return from the actual callout execution 1037 * the migration will occur in softclock_call_cc 1038 * and this new callout will be placed on the 1039 * new CPU via a call to callout_cpu_switch() which 1040 * will get the lock on the right CPU followed 1041 * by a call callout_cc_add() which will add it there. 1042 * (see above in softclock_call_cc()). 1043 */ 1044 cc_migration_cpu(cc, direct) = cpu; 1045 cc_migration_time(cc, direct) = to_sbt; 1046 cc_migration_prec(cc, direct) = precision; 1047 cc_migration_func(cc, direct) = ftn; 1048 cc_migration_arg(cc, direct) = arg; 1049 c->c_iflags |= (CALLOUT_DFRMIGRATION | CALLOUT_PENDING); 1050 c->c_flags |= CALLOUT_ACTIVE; 1051 CTR6(KTR_CALLOUT, 1052 "migration of %p func %p arg %p in %d.%08x to %u deferred", 1053 c, c->c_func, c->c_arg, (int)(to_sbt >> 32), 1054 (u_int)(to_sbt & 0xffffffff), cpu); 1055 CC_UNLOCK(cc); 1056 return (cancelled); 1057 } 1058 cc = callout_cpu_switch(c, cc, cpu); 1059 } 1060 #endif 1061 1062 callout_cc_add(c, cc, to_sbt, precision, ftn, arg, flags); 1063 CTR6(KTR_CALLOUT, "%sscheduled %p func %p arg %p in %d.%08x", 1064 cancelled ? "re" : "", c, c->c_func, c->c_arg, (int)(to_sbt >> 32), 1065 (u_int)(to_sbt & 0xffffffff)); 1066 CC_UNLOCK(cc); 1067 1068 return (cancelled); 1069 } 1070 1071 /* 1072 * Common idioms that can be optimized in the future. 1073 */ 1074 int 1075 callout_schedule_on(struct callout *c, int to_ticks, int cpu) 1076 { 1077 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, cpu); 1078 } 1079 1080 int 1081 callout_schedule(struct callout *c, int to_ticks) 1082 { 1083 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, c->c_cpu); 1084 } 1085 1086 int 1087 _callout_stop_safe(struct callout *c, int flags, callout_func_t *drain) 1088 { 1089 struct callout_cpu *cc, *old_cc; 1090 struct lock_class *class; 1091 int direct, sq_locked, use_lock; 1092 int cancelled, not_on_a_list; 1093 1094 if ((flags & CS_DRAIN) != 0) 1095 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, c->c_lock, 1096 "calling %s", __func__); 1097 1098 KASSERT((flags & CS_DRAIN) == 0 || drain == NULL, 1099 ("Cannot set drain callback and CS_DRAIN flag at the same time")); 1100 1101 /* 1102 * Some old subsystems don't hold Giant while running a callout_stop(), 1103 * so just discard this check for the moment. 1104 */ 1105 if ((flags & CS_DRAIN) == 0 && c->c_lock != NULL) { 1106 if (c->c_lock == &Giant.lock_object) 1107 use_lock = mtx_owned(&Giant); 1108 else { 1109 use_lock = 1; 1110 class = LOCK_CLASS(c->c_lock); 1111 class->lc_assert(c->c_lock, LA_XLOCKED); 1112 } 1113 } else 1114 use_lock = 0; 1115 if (c->c_iflags & CALLOUT_DIRECT) { 1116 direct = 1; 1117 } else { 1118 direct = 0; 1119 } 1120 sq_locked = 0; 1121 old_cc = NULL; 1122 again: 1123 cc = callout_lock(c); 1124 1125 if ((c->c_iflags & (CALLOUT_DFRMIGRATION | CALLOUT_PENDING)) == 1126 (CALLOUT_DFRMIGRATION | CALLOUT_PENDING) && 1127 ((c->c_flags & CALLOUT_ACTIVE) == CALLOUT_ACTIVE)) { 1128 /* 1129 * Special case where this slipped in while we 1130 * were migrating *as* the callout is about to 1131 * execute. The caller probably holds the lock 1132 * the callout wants. 1133 * 1134 * Get rid of the migration first. Then set 1135 * the flag that tells this code *not* to 1136 * try to remove it from any lists (its not 1137 * on one yet). When the callout wheel runs, 1138 * it will ignore this callout. 1139 */ 1140 c->c_iflags &= ~CALLOUT_PENDING; 1141 c->c_flags &= ~CALLOUT_ACTIVE; 1142 not_on_a_list = 1; 1143 } else { 1144 not_on_a_list = 0; 1145 } 1146 1147 /* 1148 * If the callout was migrating while the callout cpu lock was 1149 * dropped, just drop the sleepqueue lock and check the states 1150 * again. 1151 */ 1152 if (sq_locked != 0 && cc != old_cc) { 1153 #ifdef SMP 1154 CC_UNLOCK(cc); 1155 sleepq_release(&cc_exec_waiting(old_cc, direct)); 1156 sq_locked = 0; 1157 old_cc = NULL; 1158 goto again; 1159 #else 1160 panic("migration should not happen"); 1161 #endif 1162 } 1163 1164 /* 1165 * If the callout is running, try to stop it or drain it. 1166 */ 1167 if (cc_exec_curr(cc, direct) == c) { 1168 /* 1169 * Succeed we to stop it or not, we must clear the 1170 * active flag - this is what API users expect. If we're 1171 * draining and the callout is currently executing, first wait 1172 * until it finishes. 1173 */ 1174 if ((flags & CS_DRAIN) == 0) 1175 c->c_flags &= ~CALLOUT_ACTIVE; 1176 1177 if ((flags & CS_DRAIN) != 0) { 1178 /* 1179 * The current callout is running (or just 1180 * about to run) and blocking is allowed, so 1181 * just wait for the current invocation to 1182 * finish. 1183 */ 1184 if (cc_exec_curr(cc, direct) == c) { 1185 /* 1186 * Use direct calls to sleepqueue interface 1187 * instead of cv/msleep in order to avoid 1188 * a LOR between cc_lock and sleepqueue 1189 * chain spinlocks. This piece of code 1190 * emulates a msleep_spin() call actually. 1191 * 1192 * If we already have the sleepqueue chain 1193 * locked, then we can safely block. If we 1194 * don't already have it locked, however, 1195 * we have to drop the cc_lock to lock 1196 * it. This opens several races, so we 1197 * restart at the beginning once we have 1198 * both locks. If nothing has changed, then 1199 * we will end up back here with sq_locked 1200 * set. 1201 */ 1202 if (!sq_locked) { 1203 CC_UNLOCK(cc); 1204 sleepq_lock( 1205 &cc_exec_waiting(cc, direct)); 1206 sq_locked = 1; 1207 old_cc = cc; 1208 goto again; 1209 } 1210 1211 /* 1212 * Migration could be cancelled here, but 1213 * as long as it is still not sure when it 1214 * will be packed up, just let softclock() 1215 * take care of it. 1216 */ 1217 cc_exec_waiting(cc, direct) = true; 1218 DROP_GIANT(); 1219 CC_UNLOCK(cc); 1220 sleepq_add( 1221 &cc_exec_waiting(cc, direct), 1222 &cc->cc_lock.lock_object, "codrain", 1223 SLEEPQ_SLEEP, 0); 1224 sleepq_wait( 1225 &cc_exec_waiting(cc, direct), 1226 0); 1227 sq_locked = 0; 1228 old_cc = NULL; 1229 1230 /* Reacquire locks previously released. */ 1231 PICKUP_GIANT(); 1232 goto again; 1233 } 1234 c->c_flags &= ~CALLOUT_ACTIVE; 1235 } else if (use_lock && 1236 !cc_exec_cancel(cc, direct) && (drain == NULL)) { 1237 1238 /* 1239 * The current callout is waiting for its 1240 * lock which we hold. Cancel the callout 1241 * and return. After our caller drops the 1242 * lock, the callout will be skipped in 1243 * softclock(). This *only* works with a 1244 * callout_stop() *not* callout_drain() or 1245 * callout_async_drain(). 1246 */ 1247 cc_exec_cancel(cc, direct) = true; 1248 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 1249 c, c->c_func, c->c_arg); 1250 KASSERT(!cc_cce_migrating(cc, direct), 1251 ("callout wrongly scheduled for migration")); 1252 if (callout_migrating(c)) { 1253 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 1254 #ifdef SMP 1255 cc_migration_cpu(cc, direct) = CPUBLOCK; 1256 cc_migration_time(cc, direct) = 0; 1257 cc_migration_prec(cc, direct) = 0; 1258 cc_migration_func(cc, direct) = NULL; 1259 cc_migration_arg(cc, direct) = NULL; 1260 #endif 1261 } 1262 CC_UNLOCK(cc); 1263 KASSERT(!sq_locked, ("sleepqueue chain locked")); 1264 return (1); 1265 } else if (callout_migrating(c)) { 1266 /* 1267 * The callout is currently being serviced 1268 * and the "next" callout is scheduled at 1269 * its completion with a migration. We remove 1270 * the migration flag so it *won't* get rescheduled, 1271 * but we can't stop the one thats running so 1272 * we return 0. 1273 */ 1274 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 1275 #ifdef SMP 1276 /* 1277 * We can't call cc_cce_cleanup here since 1278 * if we do it will remove .ce_curr and 1279 * its still running. This will prevent a 1280 * reschedule of the callout when the 1281 * execution completes. 1282 */ 1283 cc_migration_cpu(cc, direct) = CPUBLOCK; 1284 cc_migration_time(cc, direct) = 0; 1285 cc_migration_prec(cc, direct) = 0; 1286 cc_migration_func(cc, direct) = NULL; 1287 cc_migration_arg(cc, direct) = NULL; 1288 #endif 1289 CTR3(KTR_CALLOUT, "postponing stop %p func %p arg %p", 1290 c, c->c_func, c->c_arg); 1291 if (drain) { 1292 KASSERT(cc_exec_drain(cc, direct) == NULL, 1293 ("callout drain function already set to %p", 1294 cc_exec_drain(cc, direct))); 1295 cc_exec_drain(cc, direct) = drain; 1296 } 1297 CC_UNLOCK(cc); 1298 return (0); 1299 } else { 1300 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 1301 c, c->c_func, c->c_arg); 1302 if (drain) { 1303 KASSERT(cc_exec_drain(cc, direct) == NULL, 1304 ("callout drain function already set to %p", 1305 cc_exec_drain(cc, direct))); 1306 cc_exec_drain(cc, direct) = drain; 1307 } 1308 } 1309 KASSERT(!sq_locked, ("sleepqueue chain still locked")); 1310 cancelled = 0; 1311 } else 1312 cancelled = 1; 1313 1314 if (sq_locked) 1315 sleepq_release(&cc_exec_waiting(cc, direct)); 1316 1317 if ((c->c_iflags & CALLOUT_PENDING) == 0) { 1318 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 1319 c, c->c_func, c->c_arg); 1320 /* 1321 * For not scheduled and not executing callout return 1322 * negative value. 1323 */ 1324 if (cc_exec_curr(cc, direct) != c) 1325 cancelled = -1; 1326 CC_UNLOCK(cc); 1327 return (cancelled); 1328 } 1329 1330 c->c_iflags &= ~CALLOUT_PENDING; 1331 c->c_flags &= ~CALLOUT_ACTIVE; 1332 1333 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 1334 c, c->c_func, c->c_arg); 1335 if (not_on_a_list == 0) { 1336 if ((c->c_iflags & CALLOUT_PROCESSED) == 0) { 1337 if (cc_exec_next(cc) == c) 1338 cc_exec_next(cc) = LIST_NEXT(c, c_links.le); 1339 LIST_REMOVE(c, c_links.le); 1340 } else { 1341 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe); 1342 } 1343 } 1344 CC_UNLOCK(cc); 1345 return (cancelled); 1346 } 1347 1348 void 1349 callout_init(struct callout *c, int mpsafe) 1350 { 1351 bzero(c, sizeof *c); 1352 if (mpsafe) { 1353 c->c_lock = NULL; 1354 c->c_iflags = CALLOUT_RETURNUNLOCKED; 1355 } else { 1356 c->c_lock = &Giant.lock_object; 1357 c->c_iflags = 0; 1358 } 1359 c->c_cpu = cc_default_cpu; 1360 } 1361 1362 void 1363 _callout_init_lock(struct callout *c, struct lock_object *lock, int flags) 1364 { 1365 bzero(c, sizeof *c); 1366 c->c_lock = lock; 1367 KASSERT((flags & ~(CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK)) == 0, 1368 ("callout_init_lock: bad flags %d", flags)); 1369 KASSERT(lock != NULL || (flags & CALLOUT_RETURNUNLOCKED) == 0, 1370 ("callout_init_lock: CALLOUT_RETURNUNLOCKED with no lock")); 1371 KASSERT(lock == NULL || !(LOCK_CLASS(lock)->lc_flags & LC_SLEEPABLE), 1372 ("%s: callout %p has sleepable lock", __func__, c)); 1373 c->c_iflags = flags & (CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK); 1374 c->c_cpu = cc_default_cpu; 1375 } 1376 1377 static int 1378 flssbt(sbintime_t sbt) 1379 { 1380 1381 sbt += (uint64_t)sbt >> 1; 1382 if (sizeof(long) >= sizeof(sbintime_t)) 1383 return (flsl(sbt)); 1384 if (sbt >= SBT_1S) 1385 return (flsl(((uint64_t)sbt) >> 32) + 32); 1386 return (flsl(sbt)); 1387 } 1388 1389 /* 1390 * Dump immediate statistic snapshot of the scheduled callouts. 1391 */ 1392 static int 1393 sysctl_kern_callout_stat(SYSCTL_HANDLER_ARGS) 1394 { 1395 struct callout *tmp; 1396 struct callout_cpu *cc; 1397 struct callout_list *sc; 1398 sbintime_t maxpr, maxt, medpr, medt, now, spr, st, t; 1399 int ct[64], cpr[64], ccpbk[32]; 1400 int error, val, i, count, tcum, pcum, maxc, c, medc; 1401 int cpu; 1402 1403 val = 0; 1404 error = sysctl_handle_int(oidp, &val, 0, req); 1405 if (error != 0 || req->newptr == NULL) 1406 return (error); 1407 count = maxc = 0; 1408 st = spr = maxt = maxpr = 0; 1409 bzero(ccpbk, sizeof(ccpbk)); 1410 bzero(ct, sizeof(ct)); 1411 bzero(cpr, sizeof(cpr)); 1412 now = sbinuptime(); 1413 CPU_FOREACH(cpu) { 1414 cc = CC_CPU(cpu); 1415 CC_LOCK(cc); 1416 for (i = 0; i < callwheelsize; i++) { 1417 sc = &cc->cc_callwheel[i]; 1418 c = 0; 1419 LIST_FOREACH(tmp, sc, c_links.le) { 1420 c++; 1421 t = tmp->c_time - now; 1422 if (t < 0) 1423 t = 0; 1424 st += t / SBT_1US; 1425 spr += tmp->c_precision / SBT_1US; 1426 if (t > maxt) 1427 maxt = t; 1428 if (tmp->c_precision > maxpr) 1429 maxpr = tmp->c_precision; 1430 ct[flssbt(t)]++; 1431 cpr[flssbt(tmp->c_precision)]++; 1432 } 1433 if (c > maxc) 1434 maxc = c; 1435 ccpbk[fls(c + c / 2)]++; 1436 count += c; 1437 } 1438 CC_UNLOCK(cc); 1439 } 1440 1441 for (i = 0, tcum = 0; i < 64 && tcum < count / 2; i++) 1442 tcum += ct[i]; 1443 medt = (i >= 2) ? (((sbintime_t)1) << (i - 2)) : 0; 1444 for (i = 0, pcum = 0; i < 64 && pcum < count / 2; i++) 1445 pcum += cpr[i]; 1446 medpr = (i >= 2) ? (((sbintime_t)1) << (i - 2)) : 0; 1447 for (i = 0, c = 0; i < 32 && c < count / 2; i++) 1448 c += ccpbk[i]; 1449 medc = (i >= 2) ? (1 << (i - 2)) : 0; 1450 1451 printf("Scheduled callouts statistic snapshot:\n"); 1452 printf(" Callouts: %6d Buckets: %6d*%-3d Bucket size: 0.%06ds\n", 1453 count, callwheelsize, mp_ncpus, 1000000 >> CC_HASH_SHIFT); 1454 printf(" C/Bk: med %5d avg %6d.%06jd max %6d\n", 1455 medc, 1456 count / callwheelsize / mp_ncpus, 1457 (uint64_t)count * 1000000 / callwheelsize / mp_ncpus % 1000000, 1458 maxc); 1459 printf(" Time: med %5jd.%06jds avg %6jd.%06jds max %6jd.%06jds\n", 1460 medt / SBT_1S, (medt & 0xffffffff) * 1000000 >> 32, 1461 (st / count) / 1000000, (st / count) % 1000000, 1462 maxt / SBT_1S, (maxt & 0xffffffff) * 1000000 >> 32); 1463 printf(" Prec: med %5jd.%06jds avg %6jd.%06jds max %6jd.%06jds\n", 1464 medpr / SBT_1S, (medpr & 0xffffffff) * 1000000 >> 32, 1465 (spr / count) / 1000000, (spr / count) % 1000000, 1466 maxpr / SBT_1S, (maxpr & 0xffffffff) * 1000000 >> 32); 1467 printf(" Distribution: \tbuckets\t time\t tcum\t" 1468 " prec\t pcum\n"); 1469 for (i = 0, tcum = pcum = 0; i < 64; i++) { 1470 if (ct[i] == 0 && cpr[i] == 0) 1471 continue; 1472 t = (i != 0) ? (((sbintime_t)1) << (i - 1)) : 0; 1473 tcum += ct[i]; 1474 pcum += cpr[i]; 1475 printf(" %10jd.%06jds\t 2**%d\t%7d\t%7d\t%7d\t%7d\n", 1476 t / SBT_1S, (t & 0xffffffff) * 1000000 >> 32, 1477 i - 1 - (32 - CC_HASH_SHIFT), 1478 ct[i], tcum, cpr[i], pcum); 1479 } 1480 return (error); 1481 } 1482 SYSCTL_PROC(_kern, OID_AUTO, callout_stat, 1483 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, 1484 0, 0, sysctl_kern_callout_stat, "I", 1485 "Dump immediate statistic snapshot of the scheduled callouts"); 1486 1487 #ifdef DDB 1488 static void 1489 _show_callout(struct callout *c) 1490 { 1491 1492 db_printf("callout %p\n", c); 1493 #define C_DB_PRINTF(f, e) db_printf(" %s = " f "\n", #e, c->e); 1494 db_printf(" &c_links = %p\n", &(c->c_links)); 1495 C_DB_PRINTF("%" PRId64, c_time); 1496 C_DB_PRINTF("%" PRId64, c_precision); 1497 C_DB_PRINTF("%p", c_arg); 1498 C_DB_PRINTF("%p", c_func); 1499 C_DB_PRINTF("%p", c_lock); 1500 C_DB_PRINTF("%#x", c_flags); 1501 C_DB_PRINTF("%#x", c_iflags); 1502 C_DB_PRINTF("%d", c_cpu); 1503 #undef C_DB_PRINTF 1504 } 1505 1506 DB_SHOW_COMMAND(callout, db_show_callout) 1507 { 1508 1509 if (!have_addr) { 1510 db_printf("usage: show callout <struct callout *>\n"); 1511 return; 1512 } 1513 1514 _show_callout((struct callout *)addr); 1515 } 1516 1517 static void 1518 _show_last_callout(int cpu, int direct, const char *dirstr) 1519 { 1520 struct callout_cpu *cc; 1521 void *func, *arg; 1522 1523 cc = CC_CPU(cpu); 1524 func = cc_exec_last_func(cc, direct); 1525 arg = cc_exec_last_arg(cc, direct); 1526 db_printf("cpu %d last%s callout function: %p ", cpu, dirstr, func); 1527 db_printsym((db_expr_t)func, DB_STGY_ANY); 1528 db_printf("\ncpu %d last%s callout argument: %p\n", cpu, dirstr, arg); 1529 } 1530 1531 DB_SHOW_COMMAND_FLAGS(callout_last, db_show_callout_last, DB_CMD_MEMSAFE) 1532 { 1533 int cpu, last; 1534 1535 if (have_addr) { 1536 if (addr < 0 || addr > mp_maxid || CPU_ABSENT(addr)) { 1537 db_printf("no such cpu: %d\n", (int)addr); 1538 return; 1539 } 1540 cpu = last = addr; 1541 } else { 1542 cpu = 0; 1543 last = mp_maxid; 1544 } 1545 1546 while (cpu <= last) { 1547 if (!CPU_ABSENT(cpu)) { 1548 _show_last_callout(cpu, 0, ""); 1549 _show_last_callout(cpu, 1, " direct"); 1550 } 1551 cpu++; 1552 } 1553 } 1554 #endif /* DDB */
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