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: releng/12.0/sys/kern/kern_timeout.c 326218 2017-11-25 23:41:05Z nwhitehorn $"); 41 42 #include "opt_callout_profiling.h" 43 #include "opt_ddb.h" 44 #if defined(__arm__) 45 #include "opt_timer.h" 46 #endif 47 #include "opt_rss.h" 48 49 #include <sys/param.h> 50 #include <sys/systm.h> 51 #include <sys/bus.h> 52 #include <sys/callout.h> 53 #include <sys/file.h> 54 #include <sys/interrupt.h> 55 #include <sys/kernel.h> 56 #include <sys/ktr.h> 57 #include <sys/lock.h> 58 #include <sys/malloc.h> 59 #include <sys/mutex.h> 60 #include <sys/proc.h> 61 #include <sys/sdt.h> 62 #include <sys/sleepqueue.h> 63 #include <sys/sysctl.h> 64 #include <sys/smp.h> 65 66 #ifdef DDB 67 #include <ddb/ddb.h> 68 #include <machine/_inttypes.h> 69 #endif 70 71 #ifdef SMP 72 #include <machine/cpu.h> 73 #endif 74 75 #ifndef NO_EVENTTIMERS 76 DPCPU_DECLARE(sbintime_t, hardclocktime); 77 #endif 78 79 SDT_PROVIDER_DEFINE(callout_execute); 80 SDT_PROBE_DEFINE1(callout_execute, , , callout__start, "struct callout *"); 81 SDT_PROBE_DEFINE1(callout_execute, , , callout__end, "struct callout *"); 82 83 #ifdef CALLOUT_PROFILING 84 static int avg_depth; 85 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0, 86 "Average number of items examined per softclock call. Units = 1/1000"); 87 static int avg_gcalls; 88 SYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0, 89 "Average number of Giant callouts made per softclock call. Units = 1/1000"); 90 static int avg_lockcalls; 91 SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls, CTLFLAG_RD, &avg_lockcalls, 0, 92 "Average number of lock callouts made per softclock call. Units = 1/1000"); 93 static int avg_mpcalls; 94 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0, 95 "Average number of MP callouts made per softclock call. Units = 1/1000"); 96 static int avg_depth_dir; 97 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth_dir, CTLFLAG_RD, &avg_depth_dir, 0, 98 "Average number of direct callouts examined per callout_process call. " 99 "Units = 1/1000"); 100 static int avg_lockcalls_dir; 101 SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls_dir, CTLFLAG_RD, 102 &avg_lockcalls_dir, 0, "Average number of lock direct callouts made per " 103 "callout_process call. Units = 1/1000"); 104 static int avg_mpcalls_dir; 105 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls_dir, CTLFLAG_RD, &avg_mpcalls_dir, 106 0, "Average number of MP direct callouts made per callout_process call. " 107 "Units = 1/1000"); 108 #endif 109 110 static int ncallout; 111 SYSCTL_INT(_kern, OID_AUTO, ncallout, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &ncallout, 0, 112 "Number of entries in callwheel and size of timeout() preallocation"); 113 114 #ifdef RSS 115 static int pin_default_swi = 1; 116 static int pin_pcpu_swi = 1; 117 #else 118 static int pin_default_swi = 0; 119 static int pin_pcpu_swi = 0; 120 #endif 121 122 SYSCTL_INT(_kern, OID_AUTO, pin_default_swi, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &pin_default_swi, 123 0, "Pin the default (non-per-cpu) swi (shared with PCPU 0 swi)"); 124 SYSCTL_INT(_kern, OID_AUTO, pin_pcpu_swi, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &pin_pcpu_swi, 125 0, "Pin the per-CPU swis (except PCPU 0, which is also default"); 126 127 /* 128 * TODO: 129 * allocate more timeout table slots when table overflows. 130 */ 131 u_int callwheelsize, 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_drain)(void *); 146 #ifdef SMP 147 void (*ce_migration_func)(void *); 148 void *ce_migration_arg; 149 int ce_migration_cpu; 150 sbintime_t ce_migration_time; 151 sbintime_t ce_migration_prec; 152 #endif 153 bool cc_cancel; 154 bool cc_waiting; 155 }; 156 157 /* 158 * There is one struct callout_cpu per cpu, holding all relevant 159 * state for the callout processing thread on the individual CPU. 160 */ 161 struct callout_cpu { 162 struct mtx_padalign cc_lock; 163 struct cc_exec cc_exec_entity[2]; 164 struct callout *cc_next; 165 struct callout *cc_callout; 166 struct callout_list *cc_callwheel; 167 struct callout_tailq cc_expireq; 168 struct callout_slist cc_callfree; 169 sbintime_t cc_firstevent; 170 sbintime_t cc_lastscan; 171 void *cc_cookie; 172 u_int cc_bucket; 173 u_int cc_inited; 174 char cc_ktr_event_name[20]; 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_drain(cc, dir) cc->cc_exec_entity[dir].cc_drain 181 #define cc_exec_next(cc) cc->cc_next 182 #define cc_exec_cancel(cc, dir) cc->cc_exec_entity[dir].cc_cancel 183 #define cc_exec_waiting(cc, dir) cc->cc_exec_entity[dir].cc_waiting 184 #ifdef SMP 185 #define cc_migration_func(cc, dir) cc->cc_exec_entity[dir].ce_migration_func 186 #define cc_migration_arg(cc, dir) cc->cc_exec_entity[dir].ce_migration_arg 187 #define cc_migration_cpu(cc, dir) cc->cc_exec_entity[dir].ce_migration_cpu 188 #define cc_migration_time(cc, dir) cc->cc_exec_entity[dir].ce_migration_time 189 #define cc_migration_prec(cc, dir) cc->cc_exec_entity[dir].ce_migration_prec 190 191 struct callout_cpu cc_cpu[MAXCPU]; 192 #define CPUBLOCK MAXCPU 193 #define CC_CPU(cpu) (&cc_cpu[(cpu)]) 194 #define CC_SELF() CC_CPU(PCPU_GET(cpuid)) 195 #else 196 struct callout_cpu cc_cpu; 197 #define CC_CPU(cpu) &cc_cpu 198 #define CC_SELF() &cc_cpu 199 #endif 200 #define CC_LOCK(cc) mtx_lock_spin(&(cc)->cc_lock) 201 #define CC_UNLOCK(cc) mtx_unlock_spin(&(cc)->cc_lock) 202 #define CC_LOCK_ASSERT(cc) mtx_assert(&(cc)->cc_lock, MA_OWNED) 203 204 static int timeout_cpu; 205 206 static void callout_cpu_init(struct callout_cpu *cc, int cpu); 207 static void softclock_call_cc(struct callout *c, struct callout_cpu *cc, 208 #ifdef CALLOUT_PROFILING 209 int *mpcalls, int *lockcalls, int *gcalls, 210 #endif 211 int direct); 212 213 static MALLOC_DEFINE(M_CALLOUT, "callout", "Callout datastructures"); 214 215 /** 216 * Locked by cc_lock: 217 * cc_curr - If a callout is in progress, it is cc_curr. 218 * If cc_curr is non-NULL, threads waiting in 219 * callout_drain() will be woken up as soon as the 220 * relevant callout completes. 221 * cc_cancel - Changing to 1 with both callout_lock and cc_lock held 222 * guarantees that the current callout will not run. 223 * The softclock() function sets this to 0 before it 224 * drops callout_lock to acquire c_lock, and it calls 225 * the handler only if curr_cancelled is still 0 after 226 * cc_lock is successfully acquired. 227 * cc_waiting - If a thread is waiting in callout_drain(), then 228 * callout_wait is nonzero. Set only when 229 * cc_curr is non-NULL. 230 */ 231 232 /* 233 * Resets the execution entity tied to a specific callout cpu. 234 */ 235 static void 236 cc_cce_cleanup(struct callout_cpu *cc, int direct) 237 { 238 239 cc_exec_curr(cc, direct) = NULL; 240 cc_exec_cancel(cc, direct) = false; 241 cc_exec_waiting(cc, direct) = false; 242 #ifdef SMP 243 cc_migration_cpu(cc, direct) = CPUBLOCK; 244 cc_migration_time(cc, direct) = 0; 245 cc_migration_prec(cc, direct) = 0; 246 cc_migration_func(cc, direct) = NULL; 247 cc_migration_arg(cc, direct) = NULL; 248 #endif 249 } 250 251 /* 252 * Checks if migration is requested by a specific callout cpu. 253 */ 254 static int 255 cc_cce_migrating(struct callout_cpu *cc, int direct) 256 { 257 258 #ifdef SMP 259 return (cc_migration_cpu(cc, direct) != CPUBLOCK); 260 #else 261 return (0); 262 #endif 263 } 264 265 /* 266 * Kernel low level callwheel initialization 267 * called on the BSP during kernel startup. 268 */ 269 static void 270 callout_callwheel_init(void *dummy) 271 { 272 struct callout_cpu *cc; 273 274 /* 275 * Calculate the size of the callout wheel and the preallocated 276 * timeout() structures. 277 * XXX: Clip callout to result of previous function of maxusers 278 * maximum 384. This is still huge, but acceptable. 279 */ 280 memset(CC_CPU(curcpu), 0, sizeof(cc_cpu)); 281 ncallout = imin(16 + maxproc + maxfiles, 18508); 282 TUNABLE_INT_FETCH("kern.ncallout", &ncallout); 283 284 /* 285 * Calculate callout wheel size, should be next power of two higher 286 * than 'ncallout'. 287 */ 288 callwheelsize = 1 << fls(ncallout); 289 callwheelmask = callwheelsize - 1; 290 291 /* 292 * Fetch whether we're pinning the swi's or not. 293 */ 294 TUNABLE_INT_FETCH("kern.pin_default_swi", &pin_default_swi); 295 TUNABLE_INT_FETCH("kern.pin_pcpu_swi", &pin_pcpu_swi); 296 297 /* 298 * Only BSP handles timeout(9) and receives a preallocation. 299 * 300 * XXX: Once all timeout(9) consumers are converted this can 301 * be removed. 302 */ 303 timeout_cpu = PCPU_GET(cpuid); 304 cc = CC_CPU(timeout_cpu); 305 cc->cc_callout = malloc(ncallout * sizeof(struct callout), 306 M_CALLOUT, M_WAITOK); 307 callout_cpu_init(cc, timeout_cpu); 308 } 309 SYSINIT(callwheel_init, SI_SUB_CPU, SI_ORDER_ANY, callout_callwheel_init, NULL); 310 311 /* 312 * Initialize the per-cpu callout structures. 313 */ 314 static void 315 callout_cpu_init(struct callout_cpu *cc, int cpu) 316 { 317 struct callout *c; 318 int i; 319 320 mtx_init(&cc->cc_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE); 321 SLIST_INIT(&cc->cc_callfree); 322 cc->cc_inited = 1; 323 cc->cc_callwheel = malloc(sizeof(struct callout_list) * callwheelsize, 324 M_CALLOUT, M_WAITOK); 325 for (i = 0; i < callwheelsize; i++) 326 LIST_INIT(&cc->cc_callwheel[i]); 327 TAILQ_INIT(&cc->cc_expireq); 328 cc->cc_firstevent = SBT_MAX; 329 for (i = 0; i < 2; i++) 330 cc_cce_cleanup(cc, i); 331 snprintf(cc->cc_ktr_event_name, sizeof(cc->cc_ktr_event_name), 332 "callwheel cpu %d", cpu); 333 if (cc->cc_callout == NULL) /* Only BSP handles timeout(9) */ 334 return; 335 for (i = 0; i < ncallout; i++) { 336 c = &cc->cc_callout[i]; 337 callout_init(c, 0); 338 c->c_iflags = CALLOUT_LOCAL_ALLOC; 339 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle); 340 } 341 } 342 343 #ifdef SMP 344 /* 345 * Switches the cpu tied to a specific callout. 346 * The function expects a locked incoming callout cpu and returns with 347 * locked outcoming callout cpu. 348 */ 349 static struct callout_cpu * 350 callout_cpu_switch(struct callout *c, struct callout_cpu *cc, int new_cpu) 351 { 352 struct callout_cpu *new_cc; 353 354 MPASS(c != NULL && cc != NULL); 355 CC_LOCK_ASSERT(cc); 356 357 /* 358 * Avoid interrupts and preemption firing after the callout cpu 359 * is blocked in order to avoid deadlocks as the new thread 360 * may be willing to acquire the callout cpu lock. 361 */ 362 c->c_cpu = CPUBLOCK; 363 spinlock_enter(); 364 CC_UNLOCK(cc); 365 new_cc = CC_CPU(new_cpu); 366 CC_LOCK(new_cc); 367 spinlock_exit(); 368 c->c_cpu = new_cpu; 369 return (new_cc); 370 } 371 #endif 372 373 /* 374 * Start standard softclock thread. 375 */ 376 static void 377 start_softclock(void *dummy) 378 { 379 struct callout_cpu *cc; 380 char name[MAXCOMLEN]; 381 #ifdef SMP 382 int cpu; 383 struct intr_event *ie; 384 #endif 385 386 cc = CC_CPU(timeout_cpu); 387 snprintf(name, sizeof(name), "clock (%d)", timeout_cpu); 388 if (swi_add(&clk_intr_event, name, softclock, cc, SWI_CLOCK, 389 INTR_MPSAFE, &cc->cc_cookie)) 390 panic("died while creating standard software ithreads"); 391 if (pin_default_swi && 392 (intr_event_bind(clk_intr_event, timeout_cpu) != 0)) { 393 printf("%s: timeout clock couldn't be pinned to cpu %d\n", 394 __func__, 395 timeout_cpu); 396 } 397 398 #ifdef SMP 399 CPU_FOREACH(cpu) { 400 if (cpu == timeout_cpu) 401 continue; 402 cc = CC_CPU(cpu); 403 cc->cc_callout = NULL; /* Only BSP handles timeout(9). */ 404 callout_cpu_init(cc, cpu); 405 snprintf(name, sizeof(name), "clock (%d)", cpu); 406 ie = NULL; 407 if (swi_add(&ie, name, softclock, cc, SWI_CLOCK, 408 INTR_MPSAFE, &cc->cc_cookie)) 409 panic("died while creating standard software ithreads"); 410 if (pin_pcpu_swi && (intr_event_bind(ie, cpu) != 0)) { 411 printf("%s: per-cpu clock couldn't be pinned to " 412 "cpu %d\n", 413 __func__, 414 cpu); 415 } 416 } 417 #endif 418 } 419 SYSINIT(start_softclock, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_softclock, NULL); 420 421 #define CC_HASH_SHIFT 8 422 423 static inline u_int 424 callout_hash(sbintime_t sbt) 425 { 426 427 return (sbt >> (32 - CC_HASH_SHIFT)); 428 } 429 430 static inline u_int 431 callout_get_bucket(sbintime_t sbt) 432 { 433 434 return (callout_hash(sbt) & callwheelmask); 435 } 436 437 void 438 callout_process(sbintime_t now) 439 { 440 struct callout *tmp, *tmpn; 441 struct callout_cpu *cc; 442 struct callout_list *sc; 443 sbintime_t first, last, max, tmp_max; 444 uint32_t lookahead; 445 u_int firstb, lastb, nowb; 446 #ifdef CALLOUT_PROFILING 447 int depth_dir = 0, mpcalls_dir = 0, lockcalls_dir = 0; 448 #endif 449 450 cc = CC_SELF(); 451 mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET); 452 453 /* Compute the buckets of the last scan and present times. */ 454 firstb = callout_hash(cc->cc_lastscan); 455 cc->cc_lastscan = now; 456 nowb = callout_hash(now); 457 458 /* Compute the last bucket and minimum time of the bucket after it. */ 459 if (nowb == firstb) 460 lookahead = (SBT_1S / 16); 461 else if (nowb - firstb == 1) 462 lookahead = (SBT_1S / 8); 463 else 464 lookahead = (SBT_1S / 2); 465 first = last = now; 466 first += (lookahead / 2); 467 last += lookahead; 468 last &= (0xffffffffffffffffLLU << (32 - CC_HASH_SHIFT)); 469 lastb = callout_hash(last) - 1; 470 max = last; 471 472 /* 473 * Check if we wrapped around the entire wheel from the last scan. 474 * In case, we need to scan entirely the wheel for pending callouts. 475 */ 476 if (lastb - firstb >= callwheelsize) { 477 lastb = firstb + callwheelsize - 1; 478 if (nowb - firstb >= callwheelsize) 479 nowb = lastb; 480 } 481 482 /* Iterate callwheel from firstb to nowb and then up to lastb. */ 483 do { 484 sc = &cc->cc_callwheel[firstb & callwheelmask]; 485 tmp = LIST_FIRST(sc); 486 while (tmp != NULL) { 487 /* Run the callout if present time within allowed. */ 488 if (tmp->c_time <= now) { 489 /* 490 * Consumer told us the callout may be run 491 * directly from hardware interrupt context. 492 */ 493 if (tmp->c_iflags & CALLOUT_DIRECT) { 494 #ifdef CALLOUT_PROFILING 495 ++depth_dir; 496 #endif 497 cc_exec_next(cc) = 498 LIST_NEXT(tmp, c_links.le); 499 cc->cc_bucket = firstb & callwheelmask; 500 LIST_REMOVE(tmp, c_links.le); 501 softclock_call_cc(tmp, cc, 502 #ifdef CALLOUT_PROFILING 503 &mpcalls_dir, &lockcalls_dir, NULL, 504 #endif 505 1); 506 tmp = cc_exec_next(cc); 507 cc_exec_next(cc) = NULL; 508 } else { 509 tmpn = LIST_NEXT(tmp, c_links.le); 510 LIST_REMOVE(tmp, c_links.le); 511 TAILQ_INSERT_TAIL(&cc->cc_expireq, 512 tmp, c_links.tqe); 513 tmp->c_iflags |= CALLOUT_PROCESSED; 514 tmp = tmpn; 515 } 516 continue; 517 } 518 /* Skip events from distant future. */ 519 if (tmp->c_time >= max) 520 goto next; 521 /* 522 * Event minimal time is bigger than present maximal 523 * time, so it cannot be aggregated. 524 */ 525 if (tmp->c_time > last) { 526 lastb = nowb; 527 goto next; 528 } 529 /* Update first and last time, respecting this event. */ 530 if (tmp->c_time < first) 531 first = tmp->c_time; 532 tmp_max = tmp->c_time + tmp->c_precision; 533 if (tmp_max < last) 534 last = tmp_max; 535 next: 536 tmp = LIST_NEXT(tmp, c_links.le); 537 } 538 /* Proceed with the next bucket. */ 539 firstb++; 540 /* 541 * Stop if we looked after present time and found 542 * some event we can't execute at now. 543 * Stop if we looked far enough into the future. 544 */ 545 } while (((int)(firstb - lastb)) <= 0); 546 cc->cc_firstevent = last; 547 #ifndef NO_EVENTTIMERS 548 cpu_new_callout(curcpu, last, first); 549 #endif 550 #ifdef CALLOUT_PROFILING 551 avg_depth_dir += (depth_dir * 1000 - avg_depth_dir) >> 8; 552 avg_mpcalls_dir += (mpcalls_dir * 1000 - avg_mpcalls_dir) >> 8; 553 avg_lockcalls_dir += (lockcalls_dir * 1000 - avg_lockcalls_dir) >> 8; 554 #endif 555 mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET); 556 /* 557 * swi_sched acquires the thread lock, so we don't want to call it 558 * with cc_lock held; incorrect locking order. 559 */ 560 if (!TAILQ_EMPTY(&cc->cc_expireq)) 561 swi_sched(cc->cc_cookie, 0); 562 } 563 564 static struct callout_cpu * 565 callout_lock(struct callout *c) 566 { 567 struct callout_cpu *cc; 568 int cpu; 569 570 for (;;) { 571 cpu = c->c_cpu; 572 #ifdef SMP 573 if (cpu == CPUBLOCK) { 574 while (c->c_cpu == CPUBLOCK) 575 cpu_spinwait(); 576 continue; 577 } 578 #endif 579 cc = CC_CPU(cpu); 580 CC_LOCK(cc); 581 if (cpu == c->c_cpu) 582 break; 583 CC_UNLOCK(cc); 584 } 585 return (cc); 586 } 587 588 static void 589 callout_cc_add(struct callout *c, struct callout_cpu *cc, 590 sbintime_t sbt, sbintime_t precision, void (*func)(void *), 591 void *arg, int cpu, int flags) 592 { 593 int bucket; 594 595 CC_LOCK_ASSERT(cc); 596 if (sbt < cc->cc_lastscan) 597 sbt = cc->cc_lastscan; 598 c->c_arg = arg; 599 c->c_iflags |= CALLOUT_PENDING; 600 c->c_iflags &= ~CALLOUT_PROCESSED; 601 c->c_flags |= CALLOUT_ACTIVE; 602 if (flags & C_DIRECT_EXEC) 603 c->c_iflags |= CALLOUT_DIRECT; 604 c->c_func = func; 605 c->c_time = sbt; 606 c->c_precision = precision; 607 bucket = callout_get_bucket(c->c_time); 608 CTR3(KTR_CALLOUT, "precision set for %p: %d.%08x", 609 c, (int)(c->c_precision >> 32), 610 (u_int)(c->c_precision & 0xffffffff)); 611 LIST_INSERT_HEAD(&cc->cc_callwheel[bucket], c, c_links.le); 612 if (cc->cc_bucket == bucket) 613 cc_exec_next(cc) = c; 614 #ifndef NO_EVENTTIMERS 615 /* 616 * Inform the eventtimers(4) subsystem there's a new callout 617 * that has been inserted, but only if really required. 618 */ 619 if (SBT_MAX - c->c_time < c->c_precision) 620 c->c_precision = SBT_MAX - c->c_time; 621 sbt = c->c_time + c->c_precision; 622 if (sbt < cc->cc_firstevent) { 623 cc->cc_firstevent = sbt; 624 cpu_new_callout(cpu, sbt, c->c_time); 625 } 626 #endif 627 } 628 629 static void 630 callout_cc_del(struct callout *c, struct callout_cpu *cc) 631 { 632 633 if ((c->c_iflags & CALLOUT_LOCAL_ALLOC) == 0) 634 return; 635 c->c_func = NULL; 636 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle); 637 } 638 639 static void 640 softclock_call_cc(struct callout *c, struct callout_cpu *cc, 641 #ifdef CALLOUT_PROFILING 642 int *mpcalls, int *lockcalls, int *gcalls, 643 #endif 644 int direct) 645 { 646 struct rm_priotracker tracker; 647 void (*c_func)(void *); 648 void *c_arg; 649 struct lock_class *class; 650 struct lock_object *c_lock; 651 uintptr_t lock_status; 652 int c_iflags; 653 #ifdef SMP 654 struct callout_cpu *new_cc; 655 void (*new_func)(void *); 656 void *new_arg; 657 int flags, new_cpu; 658 sbintime_t new_prec, new_time; 659 #endif 660 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING) 661 sbintime_t sbt1, sbt2; 662 struct timespec ts2; 663 static sbintime_t maxdt = 2 * SBT_1MS; /* 2 msec */ 664 static timeout_t *lastfunc; 665 #endif 666 667 KASSERT((c->c_iflags & CALLOUT_PENDING) == CALLOUT_PENDING, 668 ("softclock_call_cc: pend %p %x", c, c->c_iflags)); 669 KASSERT((c->c_flags & CALLOUT_ACTIVE) == CALLOUT_ACTIVE, 670 ("softclock_call_cc: act %p %x", c, c->c_flags)); 671 class = (c->c_lock != NULL) ? LOCK_CLASS(c->c_lock) : NULL; 672 lock_status = 0; 673 if (c->c_flags & CALLOUT_SHAREDLOCK) { 674 if (class == &lock_class_rm) 675 lock_status = (uintptr_t)&tracker; 676 else 677 lock_status = 1; 678 } 679 c_lock = c->c_lock; 680 c_func = c->c_func; 681 c_arg = c->c_arg; 682 c_iflags = c->c_iflags; 683 if (c->c_iflags & CALLOUT_LOCAL_ALLOC) 684 c->c_iflags = CALLOUT_LOCAL_ALLOC; 685 else 686 c->c_iflags &= ~CALLOUT_PENDING; 687 688 cc_exec_curr(cc, direct) = c; 689 cc_exec_cancel(cc, direct) = false; 690 cc_exec_drain(cc, direct) = NULL; 691 CC_UNLOCK(cc); 692 if (c_lock != NULL) { 693 class->lc_lock(c_lock, lock_status); 694 /* 695 * The callout may have been cancelled 696 * while we switched locks. 697 */ 698 if (cc_exec_cancel(cc, direct)) { 699 class->lc_unlock(c_lock); 700 goto skip; 701 } 702 /* The callout cannot be stopped now. */ 703 cc_exec_cancel(cc, direct) = true; 704 if (c_lock == &Giant.lock_object) { 705 #ifdef CALLOUT_PROFILING 706 (*gcalls)++; 707 #endif 708 CTR3(KTR_CALLOUT, "callout giant %p func %p arg %p", 709 c, c_func, c_arg); 710 } else { 711 #ifdef CALLOUT_PROFILING 712 (*lockcalls)++; 713 #endif 714 CTR3(KTR_CALLOUT, "callout lock %p func %p arg %p", 715 c, c_func, c_arg); 716 } 717 } else { 718 #ifdef CALLOUT_PROFILING 719 (*mpcalls)++; 720 #endif 721 CTR3(KTR_CALLOUT, "callout %p func %p arg %p", 722 c, c_func, c_arg); 723 } 724 KTR_STATE3(KTR_SCHED, "callout", cc->cc_ktr_event_name, "running", 725 "func:%p", c_func, "arg:%p", c_arg, "direct:%d", direct); 726 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING) 727 sbt1 = sbinuptime(); 728 #endif 729 THREAD_NO_SLEEPING(); 730 SDT_PROBE1(callout_execute, , , callout__start, c); 731 c_func(c_arg); 732 SDT_PROBE1(callout_execute, , , callout__end, c); 733 THREAD_SLEEPING_OK(); 734 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING) 735 sbt2 = sbinuptime(); 736 sbt2 -= sbt1; 737 if (sbt2 > maxdt) { 738 if (lastfunc != c_func || sbt2 > maxdt * 2) { 739 ts2 = sbttots(sbt2); 740 printf( 741 "Expensive timeout(9) function: %p(%p) %jd.%09ld s\n", 742 c_func, c_arg, (intmax_t)ts2.tv_sec, ts2.tv_nsec); 743 } 744 maxdt = sbt2; 745 lastfunc = c_func; 746 } 747 #endif 748 KTR_STATE0(KTR_SCHED, "callout", cc->cc_ktr_event_name, "idle"); 749 CTR1(KTR_CALLOUT, "callout %p finished", c); 750 if ((c_iflags & CALLOUT_RETURNUNLOCKED) == 0) 751 class->lc_unlock(c_lock); 752 skip: 753 CC_LOCK(cc); 754 KASSERT(cc_exec_curr(cc, direct) == c, ("mishandled cc_curr")); 755 cc_exec_curr(cc, direct) = NULL; 756 if (cc_exec_drain(cc, direct)) { 757 void (*drain)(void *); 758 759 drain = cc_exec_drain(cc, direct); 760 cc_exec_drain(cc, direct) = NULL; 761 CC_UNLOCK(cc); 762 drain(c_arg); 763 CC_LOCK(cc); 764 } 765 if (cc_exec_waiting(cc, direct)) { 766 /* 767 * There is someone waiting for the 768 * callout to complete. 769 * If the callout was scheduled for 770 * migration just cancel it. 771 */ 772 if (cc_cce_migrating(cc, direct)) { 773 cc_cce_cleanup(cc, direct); 774 775 /* 776 * It should be assert here that the callout is not 777 * destroyed but that is not easy. 778 */ 779 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 780 } 781 cc_exec_waiting(cc, direct) = false; 782 CC_UNLOCK(cc); 783 wakeup(&cc_exec_waiting(cc, direct)); 784 CC_LOCK(cc); 785 } else if (cc_cce_migrating(cc, direct)) { 786 KASSERT((c_iflags & CALLOUT_LOCAL_ALLOC) == 0, 787 ("Migrating legacy callout %p", c)); 788 #ifdef SMP 789 /* 790 * If the callout was scheduled for 791 * migration just perform it now. 792 */ 793 new_cpu = cc_migration_cpu(cc, direct); 794 new_time = cc_migration_time(cc, direct); 795 new_prec = cc_migration_prec(cc, direct); 796 new_func = cc_migration_func(cc, direct); 797 new_arg = cc_migration_arg(cc, direct); 798 cc_cce_cleanup(cc, direct); 799 800 /* 801 * It should be assert here that the callout is not destroyed 802 * but that is not easy. 803 * 804 * As first thing, handle deferred callout stops. 805 */ 806 if (!callout_migrating(c)) { 807 CTR3(KTR_CALLOUT, 808 "deferred cancelled %p func %p arg %p", 809 c, new_func, new_arg); 810 callout_cc_del(c, cc); 811 return; 812 } 813 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 814 815 new_cc = callout_cpu_switch(c, cc, new_cpu); 816 flags = (direct) ? C_DIRECT_EXEC : 0; 817 callout_cc_add(c, new_cc, new_time, new_prec, new_func, 818 new_arg, new_cpu, flags); 819 CC_UNLOCK(new_cc); 820 CC_LOCK(cc); 821 #else 822 panic("migration should not happen"); 823 #endif 824 } 825 /* 826 * If the current callout is locally allocated (from 827 * timeout(9)) then put it on the freelist. 828 * 829 * Note: we need to check the cached copy of c_iflags because 830 * if it was not local, then it's not safe to deref the 831 * callout pointer. 832 */ 833 KASSERT((c_iflags & CALLOUT_LOCAL_ALLOC) == 0 || 834 c->c_iflags == CALLOUT_LOCAL_ALLOC, 835 ("corrupted callout")); 836 if (c_iflags & CALLOUT_LOCAL_ALLOC) 837 callout_cc_del(c, cc); 838 } 839 840 /* 841 * The callout mechanism is based on the work of Adam M. Costello and 842 * George Varghese, published in a technical report entitled "Redesigning 843 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 844 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 845 * used in this implementation was published by G. Varghese and T. Lauck in 846 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 847 * the Efficient Implementation of a Timer Facility" in the Proceedings of 848 * the 11th ACM Annual Symposium on Operating Systems Principles, 849 * Austin, Texas Nov 1987. 850 */ 851 852 /* 853 * Software (low priority) clock interrupt. 854 * Run periodic events from timeout queue. 855 */ 856 void 857 softclock(void *arg) 858 { 859 struct callout_cpu *cc; 860 struct callout *c; 861 #ifdef CALLOUT_PROFILING 862 int depth = 0, gcalls = 0, lockcalls = 0, mpcalls = 0; 863 #endif 864 865 cc = (struct callout_cpu *)arg; 866 CC_LOCK(cc); 867 while ((c = TAILQ_FIRST(&cc->cc_expireq)) != NULL) { 868 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe); 869 softclock_call_cc(c, cc, 870 #ifdef CALLOUT_PROFILING 871 &mpcalls, &lockcalls, &gcalls, 872 #endif 873 0); 874 #ifdef CALLOUT_PROFILING 875 ++depth; 876 #endif 877 } 878 #ifdef CALLOUT_PROFILING 879 avg_depth += (depth * 1000 - avg_depth) >> 8; 880 avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8; 881 avg_lockcalls += (lockcalls * 1000 - avg_lockcalls) >> 8; 882 avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8; 883 #endif 884 CC_UNLOCK(cc); 885 } 886 887 /* 888 * timeout -- 889 * Execute a function after a specified length of time. 890 * 891 * untimeout -- 892 * Cancel previous timeout function call. 893 * 894 * callout_handle_init -- 895 * Initialize a handle so that using it with untimeout is benign. 896 * 897 * See AT&T BCI Driver Reference Manual for specification. This 898 * implementation differs from that one in that although an 899 * identification value is returned from timeout, the original 900 * arguments to timeout as well as the identifier are used to 901 * identify entries for untimeout. 902 */ 903 struct callout_handle 904 timeout(timeout_t *ftn, void *arg, int to_ticks) 905 { 906 struct callout_cpu *cc; 907 struct callout *new; 908 struct callout_handle handle; 909 910 cc = CC_CPU(timeout_cpu); 911 CC_LOCK(cc); 912 /* Fill in the next free callout structure. */ 913 new = SLIST_FIRST(&cc->cc_callfree); 914 if (new == NULL) 915 /* XXX Attempt to malloc first */ 916 panic("timeout table full"); 917 SLIST_REMOVE_HEAD(&cc->cc_callfree, c_links.sle); 918 callout_reset(new, to_ticks, ftn, arg); 919 handle.callout = new; 920 CC_UNLOCK(cc); 921 922 return (handle); 923 } 924 925 void 926 untimeout(timeout_t *ftn, void *arg, struct callout_handle handle) 927 { 928 struct callout_cpu *cc; 929 930 /* 931 * Check for a handle that was initialized 932 * by callout_handle_init, but never used 933 * for a real timeout. 934 */ 935 if (handle.callout == NULL) 936 return; 937 938 cc = callout_lock(handle.callout); 939 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 940 callout_stop(handle.callout); 941 CC_UNLOCK(cc); 942 } 943 944 void 945 callout_handle_init(struct callout_handle *handle) 946 { 947 handle->callout = NULL; 948 } 949 950 void 951 callout_when(sbintime_t sbt, sbintime_t precision, int flags, 952 sbintime_t *res, sbintime_t *prec_res) 953 { 954 sbintime_t to_sbt, to_pr; 955 956 if ((flags & (C_ABSOLUTE | C_PRECALC)) != 0) { 957 *res = sbt; 958 *prec_res = precision; 959 return; 960 } 961 if ((flags & C_HARDCLOCK) != 0 && sbt < tick_sbt) 962 sbt = tick_sbt; 963 if ((flags & C_HARDCLOCK) != 0 || 964 #ifdef NO_EVENTTIMERS 965 sbt >= sbt_timethreshold) { 966 to_sbt = getsbinuptime(); 967 968 /* Add safety belt for the case of hz > 1000. */ 969 to_sbt += tc_tick_sbt - tick_sbt; 970 #else 971 sbt >= sbt_tickthreshold) { 972 /* 973 * Obtain the time of the last hardclock() call on 974 * this CPU directly from the kern_clocksource.c. 975 * This value is per-CPU, but it is equal for all 976 * active ones. 977 */ 978 #ifdef __LP64__ 979 to_sbt = DPCPU_GET(hardclocktime); 980 #else 981 spinlock_enter(); 982 to_sbt = DPCPU_GET(hardclocktime); 983 spinlock_exit(); 984 #endif 985 #endif 986 if (cold && to_sbt == 0) 987 to_sbt = sbinuptime(); 988 if ((flags & C_HARDCLOCK) == 0) 989 to_sbt += tick_sbt; 990 } else 991 to_sbt = sbinuptime(); 992 if (SBT_MAX - to_sbt < sbt) 993 to_sbt = SBT_MAX; 994 else 995 to_sbt += sbt; 996 *res = to_sbt; 997 to_pr = ((C_PRELGET(flags) < 0) ? sbt >> tc_precexp : 998 sbt >> C_PRELGET(flags)); 999 *prec_res = to_pr > precision ? to_pr : precision; 1000 } 1001 1002 /* 1003 * New interface; clients allocate their own callout structures. 1004 * 1005 * callout_reset() - establish or change a timeout 1006 * callout_stop() - disestablish a timeout 1007 * callout_init() - initialize a callout structure so that it can 1008 * safely be passed to callout_reset() and callout_stop() 1009 * 1010 * <sys/callout.h> defines three convenience macros: 1011 * 1012 * callout_active() - returns truth if callout has not been stopped, 1013 * drained, or deactivated since the last time the callout was 1014 * reset. 1015 * callout_pending() - returns truth if callout is still waiting for timeout 1016 * callout_deactivate() - marks the callout as having been serviced 1017 */ 1018 int 1019 callout_reset_sbt_on(struct callout *c, sbintime_t sbt, sbintime_t prec, 1020 void (*ftn)(void *), void *arg, int cpu, int flags) 1021 { 1022 sbintime_t to_sbt, precision; 1023 struct callout_cpu *cc; 1024 int cancelled, direct; 1025 int ignore_cpu=0; 1026 1027 cancelled = 0; 1028 if (cpu == -1) { 1029 ignore_cpu = 1; 1030 } else if ((cpu >= MAXCPU) || 1031 ((CC_CPU(cpu))->cc_inited == 0)) { 1032 /* Invalid CPU spec */ 1033 panic("Invalid CPU in callout %d", cpu); 1034 } 1035 callout_when(sbt, prec, flags, &to_sbt, &precision); 1036 1037 /* 1038 * This flag used to be added by callout_cc_add, but the 1039 * first time you call this we could end up with the 1040 * wrong direct flag if we don't do it before we add. 1041 */ 1042 if (flags & C_DIRECT_EXEC) { 1043 direct = 1; 1044 } else { 1045 direct = 0; 1046 } 1047 KASSERT(!direct || c->c_lock == NULL, 1048 ("%s: direct callout %p has lock", __func__, c)); 1049 cc = callout_lock(c); 1050 /* 1051 * Don't allow migration of pre-allocated callouts lest they 1052 * become unbalanced or handle the case where the user does 1053 * not care. 1054 */ 1055 if ((c->c_iflags & CALLOUT_LOCAL_ALLOC) || 1056 ignore_cpu) { 1057 cpu = c->c_cpu; 1058 } 1059 1060 if (cc_exec_curr(cc, direct) == c) { 1061 /* 1062 * We're being asked to reschedule a callout which is 1063 * currently in progress. If there is a lock then we 1064 * can cancel the callout if it has not really started. 1065 */ 1066 if (c->c_lock != NULL && !cc_exec_cancel(cc, direct)) 1067 cancelled = cc_exec_cancel(cc, direct) = true; 1068 if (cc_exec_waiting(cc, direct) || cc_exec_drain(cc, direct)) { 1069 /* 1070 * Someone has called callout_drain to kill this 1071 * callout. Don't reschedule. 1072 */ 1073 CTR4(KTR_CALLOUT, "%s %p func %p arg %p", 1074 cancelled ? "cancelled" : "failed to cancel", 1075 c, c->c_func, c->c_arg); 1076 CC_UNLOCK(cc); 1077 return (cancelled); 1078 } 1079 #ifdef SMP 1080 if (callout_migrating(c)) { 1081 /* 1082 * This only occurs when a second callout_reset_sbt_on 1083 * is made after a previous one moved it into 1084 * deferred migration (below). Note we do *not* change 1085 * the prev_cpu even though the previous target may 1086 * be different. 1087 */ 1088 cc_migration_cpu(cc, direct) = cpu; 1089 cc_migration_time(cc, direct) = to_sbt; 1090 cc_migration_prec(cc, direct) = precision; 1091 cc_migration_func(cc, direct) = ftn; 1092 cc_migration_arg(cc, direct) = arg; 1093 cancelled = 1; 1094 CC_UNLOCK(cc); 1095 return (cancelled); 1096 } 1097 #endif 1098 } 1099 if (c->c_iflags & CALLOUT_PENDING) { 1100 if ((c->c_iflags & CALLOUT_PROCESSED) == 0) { 1101 if (cc_exec_next(cc) == c) 1102 cc_exec_next(cc) = LIST_NEXT(c, c_links.le); 1103 LIST_REMOVE(c, c_links.le); 1104 } else { 1105 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe); 1106 } 1107 cancelled = 1; 1108 c->c_iflags &= ~ CALLOUT_PENDING; 1109 c->c_flags &= ~ CALLOUT_ACTIVE; 1110 } 1111 1112 #ifdef SMP 1113 /* 1114 * If the callout must migrate try to perform it immediately. 1115 * If the callout is currently running, just defer the migration 1116 * to a more appropriate moment. 1117 */ 1118 if (c->c_cpu != cpu) { 1119 if (cc_exec_curr(cc, direct) == c) { 1120 /* 1121 * Pending will have been removed since we are 1122 * actually executing the callout on another 1123 * CPU. That callout should be waiting on the 1124 * lock the caller holds. If we set both 1125 * active/and/pending after we return and the 1126 * lock on the executing callout proceeds, it 1127 * will then see pending is true and return. 1128 * At the return from the actual callout execution 1129 * the migration will occur in softclock_call_cc 1130 * and this new callout will be placed on the 1131 * new CPU via a call to callout_cpu_switch() which 1132 * will get the lock on the right CPU followed 1133 * by a call callout_cc_add() which will add it there. 1134 * (see above in softclock_call_cc()). 1135 */ 1136 cc_migration_cpu(cc, direct) = cpu; 1137 cc_migration_time(cc, direct) = to_sbt; 1138 cc_migration_prec(cc, direct) = precision; 1139 cc_migration_func(cc, direct) = ftn; 1140 cc_migration_arg(cc, direct) = arg; 1141 c->c_iflags |= (CALLOUT_DFRMIGRATION | CALLOUT_PENDING); 1142 c->c_flags |= CALLOUT_ACTIVE; 1143 CTR6(KTR_CALLOUT, 1144 "migration of %p func %p arg %p in %d.%08x to %u deferred", 1145 c, c->c_func, c->c_arg, (int)(to_sbt >> 32), 1146 (u_int)(to_sbt & 0xffffffff), cpu); 1147 CC_UNLOCK(cc); 1148 return (cancelled); 1149 } 1150 cc = callout_cpu_switch(c, cc, cpu); 1151 } 1152 #endif 1153 1154 callout_cc_add(c, cc, to_sbt, precision, ftn, arg, cpu, flags); 1155 CTR6(KTR_CALLOUT, "%sscheduled %p func %p arg %p in %d.%08x", 1156 cancelled ? "re" : "", c, c->c_func, c->c_arg, (int)(to_sbt >> 32), 1157 (u_int)(to_sbt & 0xffffffff)); 1158 CC_UNLOCK(cc); 1159 1160 return (cancelled); 1161 } 1162 1163 /* 1164 * Common idioms that can be optimized in the future. 1165 */ 1166 int 1167 callout_schedule_on(struct callout *c, int to_ticks, int cpu) 1168 { 1169 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, cpu); 1170 } 1171 1172 int 1173 callout_schedule(struct callout *c, int to_ticks) 1174 { 1175 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, c->c_cpu); 1176 } 1177 1178 int 1179 _callout_stop_safe(struct callout *c, int flags, void (*drain)(void *)) 1180 { 1181 struct callout_cpu *cc, *old_cc; 1182 struct lock_class *class; 1183 int direct, sq_locked, use_lock; 1184 int cancelled, not_on_a_list; 1185 1186 if ((flags & CS_DRAIN) != 0) 1187 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, c->c_lock, 1188 "calling %s", __func__); 1189 1190 /* 1191 * Some old subsystems don't hold Giant while running a callout_stop(), 1192 * so just discard this check for the moment. 1193 */ 1194 if ((flags & CS_DRAIN) == 0 && c->c_lock != NULL) { 1195 if (c->c_lock == &Giant.lock_object) 1196 use_lock = mtx_owned(&Giant); 1197 else { 1198 use_lock = 1; 1199 class = LOCK_CLASS(c->c_lock); 1200 class->lc_assert(c->c_lock, LA_XLOCKED); 1201 } 1202 } else 1203 use_lock = 0; 1204 if (c->c_iflags & CALLOUT_DIRECT) { 1205 direct = 1; 1206 } else { 1207 direct = 0; 1208 } 1209 sq_locked = 0; 1210 old_cc = NULL; 1211 again: 1212 cc = callout_lock(c); 1213 1214 if ((c->c_iflags & (CALLOUT_DFRMIGRATION | CALLOUT_PENDING)) == 1215 (CALLOUT_DFRMIGRATION | CALLOUT_PENDING) && 1216 ((c->c_flags & CALLOUT_ACTIVE) == CALLOUT_ACTIVE)) { 1217 /* 1218 * Special case where this slipped in while we 1219 * were migrating *as* the callout is about to 1220 * execute. The caller probably holds the lock 1221 * the callout wants. 1222 * 1223 * Get rid of the migration first. Then set 1224 * the flag that tells this code *not* to 1225 * try to remove it from any lists (its not 1226 * on one yet). When the callout wheel runs, 1227 * it will ignore this callout. 1228 */ 1229 c->c_iflags &= ~CALLOUT_PENDING; 1230 c->c_flags &= ~CALLOUT_ACTIVE; 1231 not_on_a_list = 1; 1232 } else { 1233 not_on_a_list = 0; 1234 } 1235 1236 /* 1237 * If the callout was migrating while the callout cpu lock was 1238 * dropped, just drop the sleepqueue lock and check the states 1239 * again. 1240 */ 1241 if (sq_locked != 0 && cc != old_cc) { 1242 #ifdef SMP 1243 CC_UNLOCK(cc); 1244 sleepq_release(&cc_exec_waiting(old_cc, direct)); 1245 sq_locked = 0; 1246 old_cc = NULL; 1247 goto again; 1248 #else 1249 panic("migration should not happen"); 1250 #endif 1251 } 1252 1253 /* 1254 * If the callout is running, try to stop it or drain it. 1255 */ 1256 if (cc_exec_curr(cc, direct) == c) { 1257 /* 1258 * Succeed we to stop it or not, we must clear the 1259 * active flag - this is what API users expect. If we're 1260 * draining and the callout is currently executing, first wait 1261 * until it finishes. 1262 */ 1263 if ((flags & CS_DRAIN) == 0) 1264 c->c_flags &= ~CALLOUT_ACTIVE; 1265 1266 if ((flags & CS_DRAIN) != 0) { 1267 /* 1268 * The current callout is running (or just 1269 * about to run) and blocking is allowed, so 1270 * just wait for the current invocation to 1271 * finish. 1272 */ 1273 while (cc_exec_curr(cc, direct) == c) { 1274 /* 1275 * Use direct calls to sleepqueue interface 1276 * instead of cv/msleep in order to avoid 1277 * a LOR between cc_lock and sleepqueue 1278 * chain spinlocks. This piece of code 1279 * emulates a msleep_spin() call actually. 1280 * 1281 * If we already have the sleepqueue chain 1282 * locked, then we can safely block. If we 1283 * don't already have it locked, however, 1284 * we have to drop the cc_lock to lock 1285 * it. This opens several races, so we 1286 * restart at the beginning once we have 1287 * both locks. If nothing has changed, then 1288 * we will end up back here with sq_locked 1289 * set. 1290 */ 1291 if (!sq_locked) { 1292 CC_UNLOCK(cc); 1293 sleepq_lock( 1294 &cc_exec_waiting(cc, direct)); 1295 sq_locked = 1; 1296 old_cc = cc; 1297 goto again; 1298 } 1299 1300 /* 1301 * Migration could be cancelled here, but 1302 * as long as it is still not sure when it 1303 * will be packed up, just let softclock() 1304 * take care of it. 1305 */ 1306 cc_exec_waiting(cc, direct) = true; 1307 DROP_GIANT(); 1308 CC_UNLOCK(cc); 1309 sleepq_add( 1310 &cc_exec_waiting(cc, direct), 1311 &cc->cc_lock.lock_object, "codrain", 1312 SLEEPQ_SLEEP, 0); 1313 sleepq_wait( 1314 &cc_exec_waiting(cc, direct), 1315 0); 1316 sq_locked = 0; 1317 old_cc = NULL; 1318 1319 /* Reacquire locks previously released. */ 1320 PICKUP_GIANT(); 1321 CC_LOCK(cc); 1322 } 1323 c->c_flags &= ~CALLOUT_ACTIVE; 1324 } else if (use_lock && 1325 !cc_exec_cancel(cc, direct) && (drain == NULL)) { 1326 1327 /* 1328 * The current callout is waiting for its 1329 * lock which we hold. Cancel the callout 1330 * and return. After our caller drops the 1331 * lock, the callout will be skipped in 1332 * softclock(). This *only* works with a 1333 * callout_stop() *not* callout_drain() or 1334 * callout_async_drain(). 1335 */ 1336 cc_exec_cancel(cc, direct) = true; 1337 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 1338 c, c->c_func, c->c_arg); 1339 KASSERT(!cc_cce_migrating(cc, direct), 1340 ("callout wrongly scheduled for migration")); 1341 if (callout_migrating(c)) { 1342 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 1343 #ifdef SMP 1344 cc_migration_cpu(cc, direct) = CPUBLOCK; 1345 cc_migration_time(cc, direct) = 0; 1346 cc_migration_prec(cc, direct) = 0; 1347 cc_migration_func(cc, direct) = NULL; 1348 cc_migration_arg(cc, direct) = NULL; 1349 #endif 1350 } 1351 CC_UNLOCK(cc); 1352 KASSERT(!sq_locked, ("sleepqueue chain locked")); 1353 return (1); 1354 } else if (callout_migrating(c)) { 1355 /* 1356 * The callout is currently being serviced 1357 * and the "next" callout is scheduled at 1358 * its completion with a migration. We remove 1359 * the migration flag so it *won't* get rescheduled, 1360 * but we can't stop the one thats running so 1361 * we return 0. 1362 */ 1363 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 1364 #ifdef SMP 1365 /* 1366 * We can't call cc_cce_cleanup here since 1367 * if we do it will remove .ce_curr and 1368 * its still running. This will prevent a 1369 * reschedule of the callout when the 1370 * execution completes. 1371 */ 1372 cc_migration_cpu(cc, direct) = CPUBLOCK; 1373 cc_migration_time(cc, direct) = 0; 1374 cc_migration_prec(cc, direct) = 0; 1375 cc_migration_func(cc, direct) = NULL; 1376 cc_migration_arg(cc, direct) = NULL; 1377 #endif 1378 CTR3(KTR_CALLOUT, "postponing stop %p func %p arg %p", 1379 c, c->c_func, c->c_arg); 1380 if (drain) { 1381 cc_exec_drain(cc, direct) = drain; 1382 } 1383 CC_UNLOCK(cc); 1384 return ((flags & CS_EXECUTING) != 0); 1385 } 1386 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 1387 c, c->c_func, c->c_arg); 1388 if (drain) { 1389 cc_exec_drain(cc, direct) = drain; 1390 } 1391 KASSERT(!sq_locked, ("sleepqueue chain still locked")); 1392 cancelled = ((flags & CS_EXECUTING) != 0); 1393 } else 1394 cancelled = 1; 1395 1396 if (sq_locked) 1397 sleepq_release(&cc_exec_waiting(cc, direct)); 1398 1399 if ((c->c_iflags & CALLOUT_PENDING) == 0) { 1400 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 1401 c, c->c_func, c->c_arg); 1402 /* 1403 * For not scheduled and not executing callout return 1404 * negative value. 1405 */ 1406 if (cc_exec_curr(cc, direct) != c) 1407 cancelled = -1; 1408 CC_UNLOCK(cc); 1409 return (cancelled); 1410 } 1411 1412 c->c_iflags &= ~CALLOUT_PENDING; 1413 c->c_flags &= ~CALLOUT_ACTIVE; 1414 1415 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 1416 c, c->c_func, c->c_arg); 1417 if (not_on_a_list == 0) { 1418 if ((c->c_iflags & CALLOUT_PROCESSED) == 0) { 1419 if (cc_exec_next(cc) == c) 1420 cc_exec_next(cc) = LIST_NEXT(c, c_links.le); 1421 LIST_REMOVE(c, c_links.le); 1422 } else { 1423 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe); 1424 } 1425 } 1426 callout_cc_del(c, cc); 1427 CC_UNLOCK(cc); 1428 return (cancelled); 1429 } 1430 1431 void 1432 callout_init(struct callout *c, int mpsafe) 1433 { 1434 bzero(c, sizeof *c); 1435 if (mpsafe) { 1436 c->c_lock = NULL; 1437 c->c_iflags = CALLOUT_RETURNUNLOCKED; 1438 } else { 1439 c->c_lock = &Giant.lock_object; 1440 c->c_iflags = 0; 1441 } 1442 c->c_cpu = timeout_cpu; 1443 } 1444 1445 void 1446 _callout_init_lock(struct callout *c, struct lock_object *lock, int flags) 1447 { 1448 bzero(c, sizeof *c); 1449 c->c_lock = lock; 1450 KASSERT((flags & ~(CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK)) == 0, 1451 ("callout_init_lock: bad flags %d", flags)); 1452 KASSERT(lock != NULL || (flags & CALLOUT_RETURNUNLOCKED) == 0, 1453 ("callout_init_lock: CALLOUT_RETURNUNLOCKED with no lock")); 1454 KASSERT(lock == NULL || !(LOCK_CLASS(lock)->lc_flags & 1455 (LC_SPINLOCK | LC_SLEEPABLE)), ("%s: invalid lock class", 1456 __func__)); 1457 c->c_iflags = flags & (CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK); 1458 c->c_cpu = timeout_cpu; 1459 } 1460 1461 #ifdef APM_FIXUP_CALLTODO 1462 /* 1463 * Adjust the kernel calltodo timeout list. This routine is used after 1464 * an APM resume to recalculate the calltodo timer list values with the 1465 * number of hz's we have been sleeping. The next hardclock() will detect 1466 * that there are fired timers and run softclock() to execute them. 1467 * 1468 * Please note, I have not done an exhaustive analysis of what code this 1469 * might break. I am motivated to have my select()'s and alarm()'s that 1470 * have expired during suspend firing upon resume so that the applications 1471 * which set the timer can do the maintanence the timer was for as close 1472 * as possible to the originally intended time. Testing this code for a 1473 * week showed that resuming from a suspend resulted in 22 to 25 timers 1474 * firing, which seemed independent on whether the suspend was 2 hours or 1475 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 1476 */ 1477 void 1478 adjust_timeout_calltodo(struct timeval *time_change) 1479 { 1480 struct callout *p; 1481 unsigned long delta_ticks; 1482 1483 /* 1484 * How many ticks were we asleep? 1485 * (stolen from tvtohz()). 1486 */ 1487 1488 /* Don't do anything */ 1489 if (time_change->tv_sec < 0) 1490 return; 1491 else if (time_change->tv_sec <= LONG_MAX / 1000000) 1492 delta_ticks = howmany(time_change->tv_sec * 1000000 + 1493 time_change->tv_usec, tick) + 1; 1494 else if (time_change->tv_sec <= LONG_MAX / hz) 1495 delta_ticks = time_change->tv_sec * hz + 1496 howmany(time_change->tv_usec, tick) + 1; 1497 else 1498 delta_ticks = LONG_MAX; 1499 1500 if (delta_ticks > INT_MAX) 1501 delta_ticks = INT_MAX; 1502 1503 /* 1504 * Now rip through the timer calltodo list looking for timers 1505 * to expire. 1506 */ 1507 1508 /* don't collide with softclock() */ 1509 CC_LOCK(cc); 1510 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 1511 p->c_time -= delta_ticks; 1512 1513 /* Break if the timer had more time on it than delta_ticks */ 1514 if (p->c_time > 0) 1515 break; 1516 1517 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 1518 delta_ticks = -p->c_time; 1519 } 1520 CC_UNLOCK(cc); 1521 1522 return; 1523 } 1524 #endif /* APM_FIXUP_CALLTODO */ 1525 1526 static int 1527 flssbt(sbintime_t sbt) 1528 { 1529 1530 sbt += (uint64_t)sbt >> 1; 1531 if (sizeof(long) >= sizeof(sbintime_t)) 1532 return (flsl(sbt)); 1533 if (sbt >= SBT_1S) 1534 return (flsl(((uint64_t)sbt) >> 32) + 32); 1535 return (flsl(sbt)); 1536 } 1537 1538 /* 1539 * Dump immediate statistic snapshot of the scheduled callouts. 1540 */ 1541 static int 1542 sysctl_kern_callout_stat(SYSCTL_HANDLER_ARGS) 1543 { 1544 struct callout *tmp; 1545 struct callout_cpu *cc; 1546 struct callout_list *sc; 1547 sbintime_t maxpr, maxt, medpr, medt, now, spr, st, t; 1548 int ct[64], cpr[64], ccpbk[32]; 1549 int error, val, i, count, tcum, pcum, maxc, c, medc; 1550 #ifdef SMP 1551 int cpu; 1552 #endif 1553 1554 val = 0; 1555 error = sysctl_handle_int(oidp, &val, 0, req); 1556 if (error != 0 || req->newptr == NULL) 1557 return (error); 1558 count = maxc = 0; 1559 st = spr = maxt = maxpr = 0; 1560 bzero(ccpbk, sizeof(ccpbk)); 1561 bzero(ct, sizeof(ct)); 1562 bzero(cpr, sizeof(cpr)); 1563 now = sbinuptime(); 1564 #ifdef SMP 1565 CPU_FOREACH(cpu) { 1566 cc = CC_CPU(cpu); 1567 #else 1568 cc = CC_CPU(timeout_cpu); 1569 #endif 1570 CC_LOCK(cc); 1571 for (i = 0; i < callwheelsize; i++) { 1572 sc = &cc->cc_callwheel[i]; 1573 c = 0; 1574 LIST_FOREACH(tmp, sc, c_links.le) { 1575 c++; 1576 t = tmp->c_time - now; 1577 if (t < 0) 1578 t = 0; 1579 st += t / SBT_1US; 1580 spr += tmp->c_precision / SBT_1US; 1581 if (t > maxt) 1582 maxt = t; 1583 if (tmp->c_precision > maxpr) 1584 maxpr = tmp->c_precision; 1585 ct[flssbt(t)]++; 1586 cpr[flssbt(tmp->c_precision)]++; 1587 } 1588 if (c > maxc) 1589 maxc = c; 1590 ccpbk[fls(c + c / 2)]++; 1591 count += c; 1592 } 1593 CC_UNLOCK(cc); 1594 #ifdef SMP 1595 } 1596 #endif 1597 1598 for (i = 0, tcum = 0; i < 64 && tcum < count / 2; i++) 1599 tcum += ct[i]; 1600 medt = (i >= 2) ? (((sbintime_t)1) << (i - 2)) : 0; 1601 for (i = 0, pcum = 0; i < 64 && pcum < count / 2; i++) 1602 pcum += cpr[i]; 1603 medpr = (i >= 2) ? (((sbintime_t)1) << (i - 2)) : 0; 1604 for (i = 0, c = 0; i < 32 && c < count / 2; i++) 1605 c += ccpbk[i]; 1606 medc = (i >= 2) ? (1 << (i - 2)) : 0; 1607 1608 printf("Scheduled callouts statistic snapshot:\n"); 1609 printf(" Callouts: %6d Buckets: %6d*%-3d Bucket size: 0.%06ds\n", 1610 count, callwheelsize, mp_ncpus, 1000000 >> CC_HASH_SHIFT); 1611 printf(" C/Bk: med %5d avg %6d.%06jd max %6d\n", 1612 medc, 1613 count / callwheelsize / mp_ncpus, 1614 (uint64_t)count * 1000000 / callwheelsize / mp_ncpus % 1000000, 1615 maxc); 1616 printf(" Time: med %5jd.%06jds avg %6jd.%06jds max %6jd.%06jds\n", 1617 medt / SBT_1S, (medt & 0xffffffff) * 1000000 >> 32, 1618 (st / count) / 1000000, (st / count) % 1000000, 1619 maxt / SBT_1S, (maxt & 0xffffffff) * 1000000 >> 32); 1620 printf(" Prec: med %5jd.%06jds avg %6jd.%06jds max %6jd.%06jds\n", 1621 medpr / SBT_1S, (medpr & 0xffffffff) * 1000000 >> 32, 1622 (spr / count) / 1000000, (spr / count) % 1000000, 1623 maxpr / SBT_1S, (maxpr & 0xffffffff) * 1000000 >> 32); 1624 printf(" Distribution: \tbuckets\t time\t tcum\t" 1625 " prec\t pcum\n"); 1626 for (i = 0, tcum = pcum = 0; i < 64; i++) { 1627 if (ct[i] == 0 && cpr[i] == 0) 1628 continue; 1629 t = (i != 0) ? (((sbintime_t)1) << (i - 1)) : 0; 1630 tcum += ct[i]; 1631 pcum += cpr[i]; 1632 printf(" %10jd.%06jds\t 2**%d\t%7d\t%7d\t%7d\t%7d\n", 1633 t / SBT_1S, (t & 0xffffffff) * 1000000 >> 32, 1634 i - 1 - (32 - CC_HASH_SHIFT), 1635 ct[i], tcum, cpr[i], pcum); 1636 } 1637 return (error); 1638 } 1639 SYSCTL_PROC(_kern, OID_AUTO, callout_stat, 1640 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, 1641 0, 0, sysctl_kern_callout_stat, "I", 1642 "Dump immediate statistic snapshot of the scheduled callouts"); 1643 1644 #ifdef DDB 1645 static void 1646 _show_callout(struct callout *c) 1647 { 1648 1649 db_printf("callout %p\n", c); 1650 #define C_DB_PRINTF(f, e) db_printf(" %s = " f "\n", #e, c->e); 1651 db_printf(" &c_links = %p\n", &(c->c_links)); 1652 C_DB_PRINTF("%" PRId64, c_time); 1653 C_DB_PRINTF("%" PRId64, c_precision); 1654 C_DB_PRINTF("%p", c_arg); 1655 C_DB_PRINTF("%p", c_func); 1656 C_DB_PRINTF("%p", c_lock); 1657 C_DB_PRINTF("%#x", c_flags); 1658 C_DB_PRINTF("%#x", c_iflags); 1659 C_DB_PRINTF("%d", c_cpu); 1660 #undef C_DB_PRINTF 1661 } 1662 1663 DB_SHOW_COMMAND(callout, db_show_callout) 1664 { 1665 1666 if (!have_addr) { 1667 db_printf("usage: show callout <struct callout *>\n"); 1668 return; 1669 } 1670 1671 _show_callout((struct callout *)addr); 1672 } 1673 #endif /* DDB */
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