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 * Copyright (c) 1982, 1986, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 4. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * From: @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 35 */ 36 37 #include <sys/cdefs.h> 38 __FBSDID("$FreeBSD: releng/10.4/sys/kern/kern_timeout.c 305853 2016-09-16 00:14:26Z hiren $"); 39 40 #include "opt_callout_profiling.h" 41 #include "opt_kdtrace.h" 42 #include "opt_ddb.h" 43 #if defined(__arm__) 44 #include "opt_timer.h" 45 #endif 46 47 #include <sys/param.h> 48 #include <sys/systm.h> 49 #include <sys/bus.h> 50 #include <sys/callout.h> 51 #include <sys/file.h> 52 #include <sys/interrupt.h> 53 #include <sys/kernel.h> 54 #include <sys/ktr.h> 55 #include <sys/lock.h> 56 #include <sys/malloc.h> 57 #include <sys/mutex.h> 58 #include <sys/proc.h> 59 #include <sys/sdt.h> 60 #include <sys/sleepqueue.h> 61 #include <sys/sysctl.h> 62 #include <sys/smp.h> 63 64 #ifdef DDB 65 #include <ddb/ddb.h> 66 #include <machine/_inttypes.h> 67 #endif 68 69 #ifdef SMP 70 #include <machine/cpu.h> 71 #endif 72 73 #ifndef NO_EVENTTIMERS 74 DPCPU_DECLARE(sbintime_t, hardclocktime); 75 #endif 76 77 SDT_PROVIDER_DEFINE(callout_execute); 78 SDT_PROBE_DEFINE1(callout_execute, , , callout__start, "struct callout *"); 79 SDT_PROBE_DEFINE1(callout_execute, , , callout__end, "struct callout *"); 80 81 #ifdef CALLOUT_PROFILING 82 static int avg_depth; 83 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0, 84 "Average number of items examined per softclock call. Units = 1/1000"); 85 static int avg_gcalls; 86 SYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0, 87 "Average number of Giant callouts made per softclock call. Units = 1/1000"); 88 static int avg_lockcalls; 89 SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls, CTLFLAG_RD, &avg_lockcalls, 0, 90 "Average number of lock callouts made per softclock call. Units = 1/1000"); 91 static int avg_mpcalls; 92 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0, 93 "Average number of MP callouts made per softclock call. Units = 1/1000"); 94 static int avg_depth_dir; 95 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth_dir, CTLFLAG_RD, &avg_depth_dir, 0, 96 "Average number of direct callouts examined per callout_process call. " 97 "Units = 1/1000"); 98 static int avg_lockcalls_dir; 99 SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls_dir, CTLFLAG_RD, 100 &avg_lockcalls_dir, 0, "Average number of lock direct callouts made per " 101 "callout_process call. Units = 1/1000"); 102 static int avg_mpcalls_dir; 103 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls_dir, CTLFLAG_RD, &avg_mpcalls_dir, 104 0, "Average number of MP direct callouts made per callout_process call. " 105 "Units = 1/1000"); 106 #endif 107 108 static int ncallout; 109 SYSCTL_INT(_kern, OID_AUTO, ncallout, CTLFLAG_RDTUN, &ncallout, 0, 110 "Number of entries in callwheel and size of timeout() preallocation"); 111 112 /* 113 * TODO: 114 * allocate more timeout table slots when table overflows. 115 */ 116 u_int callwheelsize, callwheelmask; 117 118 /* 119 * The callout cpu exec entities represent informations necessary for 120 * describing the state of callouts currently running on the CPU and the ones 121 * necessary for migrating callouts to the new callout cpu. In particular, 122 * the first entry of the array cc_exec_entity holds informations for callout 123 * running in SWI thread context, while the second one holds informations 124 * for callout running directly from hardware interrupt context. 125 * The cached informations are very important for deferring migration when 126 * the migrating callout is already running. 127 */ 128 struct cc_exec { 129 struct callout *cc_curr; 130 #ifdef SMP 131 void (*ce_migration_func)(void *); 132 void *ce_migration_arg; 133 int ce_migration_cpu; 134 sbintime_t ce_migration_time; 135 sbintime_t ce_migration_prec; 136 #endif 137 bool cc_cancel; 138 bool cc_waiting; 139 }; 140 141 /* 142 * There is one struct callout_cpu per cpu, holding all relevant 143 * state for the callout processing thread on the individual CPU. 144 */ 145 struct callout_cpu { 146 struct mtx_padalign cc_lock; 147 struct cc_exec cc_exec_entity[2]; 148 struct callout *cc_next; 149 struct callout *cc_callout; 150 struct callout_list *cc_callwheel; 151 struct callout_tailq cc_expireq; 152 struct callout_slist cc_callfree; 153 sbintime_t cc_firstevent; 154 sbintime_t cc_lastscan; 155 void *cc_cookie; 156 u_int cc_bucket; 157 u_int cc_inited; 158 char cc_ktr_event_name[20]; 159 }; 160 161 #define callout_migrating(c) ((c)->c_iflags & CALLOUT_DFRMIGRATION) 162 163 #define cc_exec_curr(cc, dir) cc->cc_exec_entity[dir].cc_curr 164 #define cc_exec_next(cc) cc->cc_next 165 #define cc_exec_cancel(cc, dir) cc->cc_exec_entity[dir].cc_cancel 166 #define cc_exec_waiting(cc, dir) cc->cc_exec_entity[dir].cc_waiting 167 #ifdef SMP 168 #define cc_migration_func(cc, dir) cc->cc_exec_entity[dir].ce_migration_func 169 #define cc_migration_arg(cc, dir) cc->cc_exec_entity[dir].ce_migration_arg 170 #define cc_migration_cpu(cc, dir) cc->cc_exec_entity[dir].ce_migration_cpu 171 #define cc_migration_time(cc, dir) cc->cc_exec_entity[dir].ce_migration_time 172 #define cc_migration_prec(cc, dir) cc->cc_exec_entity[dir].ce_migration_prec 173 174 struct callout_cpu cc_cpu[MAXCPU]; 175 #define CPUBLOCK MAXCPU 176 #define CC_CPU(cpu) (&cc_cpu[(cpu)]) 177 #define CC_SELF() CC_CPU(PCPU_GET(cpuid)) 178 #else 179 struct callout_cpu cc_cpu; 180 #define CC_CPU(cpu) &cc_cpu 181 #define CC_SELF() &cc_cpu 182 #endif 183 #define CC_LOCK(cc) mtx_lock_spin(&(cc)->cc_lock) 184 #define CC_UNLOCK(cc) mtx_unlock_spin(&(cc)->cc_lock) 185 #define CC_LOCK_ASSERT(cc) mtx_assert(&(cc)->cc_lock, MA_OWNED) 186 187 static int timeout_cpu; 188 189 static void callout_cpu_init(struct callout_cpu *cc, int cpu); 190 static void softclock_call_cc(struct callout *c, struct callout_cpu *cc, 191 #ifdef CALLOUT_PROFILING 192 int *mpcalls, int *lockcalls, int *gcalls, 193 #endif 194 int direct); 195 196 static MALLOC_DEFINE(M_CALLOUT, "callout", "Callout datastructures"); 197 198 /** 199 * Locked by cc_lock: 200 * cc_curr - If a callout is in progress, it is cc_curr. 201 * If cc_curr is non-NULL, threads waiting in 202 * callout_drain() will be woken up as soon as the 203 * relevant callout completes. 204 * cc_cancel - Changing to 1 with both callout_lock and cc_lock held 205 * guarantees that the current callout will not run. 206 * The softclock() function sets this to 0 before it 207 * drops callout_lock to acquire c_lock, and it calls 208 * the handler only if curr_cancelled is still 0 after 209 * cc_lock is successfully acquired. 210 * cc_waiting - If a thread is waiting in callout_drain(), then 211 * callout_wait is nonzero. Set only when 212 * cc_curr is non-NULL. 213 */ 214 215 /* 216 * Resets the execution entity tied to a specific callout cpu. 217 */ 218 static void 219 cc_cce_cleanup(struct callout_cpu *cc, int direct) 220 { 221 222 cc_exec_curr(cc, direct) = NULL; 223 cc_exec_cancel(cc, direct) = false; 224 cc_exec_waiting(cc, direct) = false; 225 #ifdef SMP 226 cc_migration_cpu(cc, direct) = CPUBLOCK; 227 cc_migration_time(cc, direct) = 0; 228 cc_migration_prec(cc, direct) = 0; 229 cc_migration_func(cc, direct) = NULL; 230 cc_migration_arg(cc, direct) = NULL; 231 #endif 232 } 233 234 /* 235 * Checks if migration is requested by a specific callout cpu. 236 */ 237 static int 238 cc_cce_migrating(struct callout_cpu *cc, int direct) 239 { 240 241 #ifdef SMP 242 return (cc_migration_cpu(cc, direct) != CPUBLOCK); 243 #else 244 return (0); 245 #endif 246 } 247 248 /* 249 * Kernel low level callwheel initialization 250 * called on cpu0 during kernel startup. 251 */ 252 static void 253 callout_callwheel_init(void *dummy) 254 { 255 struct callout_cpu *cc; 256 257 /* 258 * Calculate the size of the callout wheel and the preallocated 259 * timeout() structures. 260 * XXX: Clip callout to result of previous function of maxusers 261 * maximum 384. This is still huge, but acceptable. 262 */ 263 memset(CC_CPU(0), 0, sizeof(cc_cpu)); 264 ncallout = imin(16 + maxproc + maxfiles, 18508); 265 TUNABLE_INT_FETCH("kern.ncallout", &ncallout); 266 267 /* 268 * Calculate callout wheel size, should be next power of two higher 269 * than 'ncallout'. 270 */ 271 callwheelsize = 1 << fls(ncallout); 272 callwheelmask = callwheelsize - 1; 273 274 /* 275 * Only cpu0 handles timeout(9) and receives a preallocation. 276 * 277 * XXX: Once all timeout(9) consumers are converted this can 278 * be removed. 279 */ 280 timeout_cpu = PCPU_GET(cpuid); 281 cc = CC_CPU(timeout_cpu); 282 cc->cc_callout = malloc(ncallout * sizeof(struct callout), 283 M_CALLOUT, M_WAITOK); 284 callout_cpu_init(cc, timeout_cpu); 285 } 286 SYSINIT(callwheel_init, SI_SUB_CPU, SI_ORDER_ANY, callout_callwheel_init, NULL); 287 288 /* 289 * Initialize the per-cpu callout structures. 290 */ 291 static void 292 callout_cpu_init(struct callout_cpu *cc, int cpu) 293 { 294 struct callout *c; 295 int i; 296 297 mtx_init(&cc->cc_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE); 298 SLIST_INIT(&cc->cc_callfree); 299 cc->cc_inited = 1; 300 cc->cc_callwheel = malloc(sizeof(struct callout_list) * callwheelsize, 301 M_CALLOUT, M_WAITOK); 302 for (i = 0; i < callwheelsize; i++) 303 LIST_INIT(&cc->cc_callwheel[i]); 304 TAILQ_INIT(&cc->cc_expireq); 305 cc->cc_firstevent = SBT_MAX; 306 for (i = 0; i < 2; i++) 307 cc_cce_cleanup(cc, i); 308 snprintf(cc->cc_ktr_event_name, sizeof(cc->cc_ktr_event_name), 309 "callwheel cpu %d", cpu); 310 if (cc->cc_callout == NULL) /* Only cpu0 handles timeout(9) */ 311 return; 312 for (i = 0; i < ncallout; i++) { 313 c = &cc->cc_callout[i]; 314 callout_init(c, 0); 315 c->c_iflags = CALLOUT_LOCAL_ALLOC; 316 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle); 317 } 318 } 319 320 #ifdef SMP 321 /* 322 * Switches the cpu tied to a specific callout. 323 * The function expects a locked incoming callout cpu and returns with 324 * locked outcoming callout cpu. 325 */ 326 static struct callout_cpu * 327 callout_cpu_switch(struct callout *c, struct callout_cpu *cc, int new_cpu) 328 { 329 struct callout_cpu *new_cc; 330 331 MPASS(c != NULL && cc != NULL); 332 CC_LOCK_ASSERT(cc); 333 334 /* 335 * Avoid interrupts and preemption firing after the callout cpu 336 * is blocked in order to avoid deadlocks as the new thread 337 * may be willing to acquire the callout cpu lock. 338 */ 339 c->c_cpu = CPUBLOCK; 340 spinlock_enter(); 341 CC_UNLOCK(cc); 342 new_cc = CC_CPU(new_cpu); 343 CC_LOCK(new_cc); 344 spinlock_exit(); 345 c->c_cpu = new_cpu; 346 return (new_cc); 347 } 348 #endif 349 350 /* 351 * Start standard softclock thread. 352 */ 353 static void 354 start_softclock(void *dummy) 355 { 356 struct callout_cpu *cc; 357 #ifdef SMP 358 int cpu; 359 #endif 360 361 cc = CC_CPU(timeout_cpu); 362 if (swi_add(&clk_intr_event, "clock", softclock, cc, SWI_CLOCK, 363 INTR_MPSAFE, &cc->cc_cookie)) 364 panic("died while creating standard software ithreads"); 365 #ifdef SMP 366 CPU_FOREACH(cpu) { 367 if (cpu == timeout_cpu) 368 continue; 369 cc = CC_CPU(cpu); 370 cc->cc_callout = NULL; /* Only cpu0 handles timeout(9). */ 371 callout_cpu_init(cc, cpu); 372 if (swi_add(NULL, "clock", softclock, cc, SWI_CLOCK, 373 INTR_MPSAFE, &cc->cc_cookie)) 374 panic("died while creating standard software ithreads"); 375 } 376 #endif 377 } 378 SYSINIT(start_softclock, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_softclock, NULL); 379 380 #define CC_HASH_SHIFT 8 381 382 static inline u_int 383 callout_hash(sbintime_t sbt) 384 { 385 386 return (sbt >> (32 - CC_HASH_SHIFT)); 387 } 388 389 static inline u_int 390 callout_get_bucket(sbintime_t sbt) 391 { 392 393 return (callout_hash(sbt) & callwheelmask); 394 } 395 396 void 397 callout_process(sbintime_t now) 398 { 399 struct callout *tmp, *tmpn; 400 struct callout_cpu *cc; 401 struct callout_list *sc; 402 sbintime_t first, last, max, tmp_max; 403 uint32_t lookahead; 404 u_int firstb, lastb, nowb; 405 #ifdef CALLOUT_PROFILING 406 int depth_dir = 0, mpcalls_dir = 0, lockcalls_dir = 0; 407 #endif 408 409 cc = CC_SELF(); 410 mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET); 411 412 /* Compute the buckets of the last scan and present times. */ 413 firstb = callout_hash(cc->cc_lastscan); 414 cc->cc_lastscan = now; 415 nowb = callout_hash(now); 416 417 /* Compute the last bucket and minimum time of the bucket after it. */ 418 if (nowb == firstb) 419 lookahead = (SBT_1S / 16); 420 else if (nowb - firstb == 1) 421 lookahead = (SBT_1S / 8); 422 else 423 lookahead = (SBT_1S / 2); 424 first = last = now; 425 first += (lookahead / 2); 426 last += lookahead; 427 last &= (0xffffffffffffffffLLU << (32 - CC_HASH_SHIFT)); 428 lastb = callout_hash(last) - 1; 429 max = last; 430 431 /* 432 * Check if we wrapped around the entire wheel from the last scan. 433 * In case, we need to scan entirely the wheel for pending callouts. 434 */ 435 if (lastb - firstb >= callwheelsize) { 436 lastb = firstb + callwheelsize - 1; 437 if (nowb - firstb >= callwheelsize) 438 nowb = lastb; 439 } 440 441 /* Iterate callwheel from firstb to nowb and then up to lastb. */ 442 do { 443 sc = &cc->cc_callwheel[firstb & callwheelmask]; 444 tmp = LIST_FIRST(sc); 445 while (tmp != NULL) { 446 /* Run the callout if present time within allowed. */ 447 if (tmp->c_time <= now) { 448 /* 449 * Consumer told us the callout may be run 450 * directly from hardware interrupt context. 451 */ 452 if (tmp->c_iflags & CALLOUT_DIRECT) { 453 #ifdef CALLOUT_PROFILING 454 ++depth_dir; 455 #endif 456 cc_exec_next(cc) = 457 LIST_NEXT(tmp, c_links.le); 458 cc->cc_bucket = firstb & callwheelmask; 459 LIST_REMOVE(tmp, c_links.le); 460 softclock_call_cc(tmp, cc, 461 #ifdef CALLOUT_PROFILING 462 &mpcalls_dir, &lockcalls_dir, NULL, 463 #endif 464 1); 465 tmp = cc_exec_next(cc); 466 cc_exec_next(cc) = NULL; 467 } else { 468 tmpn = LIST_NEXT(tmp, c_links.le); 469 LIST_REMOVE(tmp, c_links.le); 470 TAILQ_INSERT_TAIL(&cc->cc_expireq, 471 tmp, c_links.tqe); 472 tmp->c_iflags |= CALLOUT_PROCESSED; 473 tmp = tmpn; 474 } 475 continue; 476 } 477 /* Skip events from distant future. */ 478 if (tmp->c_time >= max) 479 goto next; 480 /* 481 * Event minimal time is bigger than present maximal 482 * time, so it cannot be aggregated. 483 */ 484 if (tmp->c_time > last) { 485 lastb = nowb; 486 goto next; 487 } 488 /* Update first and last time, respecting this event. */ 489 if (tmp->c_time < first) 490 first = tmp->c_time; 491 tmp_max = tmp->c_time + tmp->c_precision; 492 if (tmp_max < last) 493 last = tmp_max; 494 next: 495 tmp = LIST_NEXT(tmp, c_links.le); 496 } 497 /* Proceed with the next bucket. */ 498 firstb++; 499 /* 500 * Stop if we looked after present time and found 501 * some event we can't execute at now. 502 * Stop if we looked far enough into the future. 503 */ 504 } while (((int)(firstb - lastb)) <= 0); 505 cc->cc_firstevent = last; 506 #ifndef NO_EVENTTIMERS 507 cpu_new_callout(curcpu, last, first); 508 #endif 509 #ifdef CALLOUT_PROFILING 510 avg_depth_dir += (depth_dir * 1000 - avg_depth_dir) >> 8; 511 avg_mpcalls_dir += (mpcalls_dir * 1000 - avg_mpcalls_dir) >> 8; 512 avg_lockcalls_dir += (lockcalls_dir * 1000 - avg_lockcalls_dir) >> 8; 513 #endif 514 mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET); 515 /* 516 * swi_sched acquires the thread lock, so we don't want to call it 517 * with cc_lock held; incorrect locking order. 518 */ 519 if (!TAILQ_EMPTY(&cc->cc_expireq)) 520 swi_sched(cc->cc_cookie, 0); 521 } 522 523 static struct callout_cpu * 524 callout_lock(struct callout *c) 525 { 526 struct callout_cpu *cc; 527 int cpu; 528 529 for (;;) { 530 cpu = c->c_cpu; 531 #ifdef SMP 532 if (cpu == CPUBLOCK) { 533 while (c->c_cpu == CPUBLOCK) 534 cpu_spinwait(); 535 continue; 536 } 537 #endif 538 cc = CC_CPU(cpu); 539 CC_LOCK(cc); 540 if (cpu == c->c_cpu) 541 break; 542 CC_UNLOCK(cc); 543 } 544 return (cc); 545 } 546 547 static void 548 callout_cc_add(struct callout *c, struct callout_cpu *cc, 549 sbintime_t sbt, sbintime_t precision, void (*func)(void *), 550 void *arg, int cpu, int flags) 551 { 552 int bucket; 553 554 CC_LOCK_ASSERT(cc); 555 if (sbt < cc->cc_lastscan) 556 sbt = cc->cc_lastscan; 557 c->c_arg = arg; 558 c->c_iflags |= CALLOUT_PENDING; 559 c->c_iflags &= ~CALLOUT_PROCESSED; 560 c->c_flags |= CALLOUT_ACTIVE; 561 if (flags & C_DIRECT_EXEC) 562 c->c_iflags |= CALLOUT_DIRECT; 563 c->c_func = func; 564 c->c_time = sbt; 565 c->c_precision = precision; 566 bucket = callout_get_bucket(c->c_time); 567 CTR3(KTR_CALLOUT, "precision set for %p: %d.%08x", 568 c, (int)(c->c_precision >> 32), 569 (u_int)(c->c_precision & 0xffffffff)); 570 LIST_INSERT_HEAD(&cc->cc_callwheel[bucket], c, c_links.le); 571 if (cc->cc_bucket == bucket) 572 cc_exec_next(cc) = c; 573 #ifndef NO_EVENTTIMERS 574 /* 575 * Inform the eventtimers(4) subsystem there's a new callout 576 * that has been inserted, but only if really required. 577 */ 578 if (SBT_MAX - c->c_time < c->c_precision) 579 c->c_precision = SBT_MAX - c->c_time; 580 sbt = c->c_time + c->c_precision; 581 if (sbt < cc->cc_firstevent) { 582 cc->cc_firstevent = sbt; 583 cpu_new_callout(cpu, sbt, c->c_time); 584 } 585 #endif 586 } 587 588 static void 589 callout_cc_del(struct callout *c, struct callout_cpu *cc) 590 { 591 592 if ((c->c_iflags & CALLOUT_LOCAL_ALLOC) == 0) 593 return; 594 c->c_func = NULL; 595 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle); 596 } 597 598 static void 599 softclock_call_cc(struct callout *c, struct callout_cpu *cc, 600 #ifdef CALLOUT_PROFILING 601 int *mpcalls, int *lockcalls, int *gcalls, 602 #endif 603 int direct) 604 { 605 struct rm_priotracker tracker; 606 void (*c_func)(void *); 607 void *c_arg; 608 struct lock_class *class; 609 struct lock_object *c_lock; 610 uintptr_t lock_status; 611 int c_iflags; 612 #ifdef SMP 613 struct callout_cpu *new_cc; 614 void (*new_func)(void *); 615 void *new_arg; 616 int flags, new_cpu; 617 sbintime_t new_prec, new_time; 618 #endif 619 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING) 620 sbintime_t sbt1, sbt2; 621 struct timespec ts2; 622 static sbintime_t maxdt = 2 * SBT_1MS; /* 2 msec */ 623 static timeout_t *lastfunc; 624 #endif 625 626 KASSERT((c->c_iflags & CALLOUT_PENDING) == CALLOUT_PENDING, 627 ("softclock_call_cc: pend %p %x", c, c->c_iflags)); 628 KASSERT((c->c_flags & CALLOUT_ACTIVE) == CALLOUT_ACTIVE, 629 ("softclock_call_cc: act %p %x", c, c->c_flags)); 630 class = (c->c_lock != NULL) ? LOCK_CLASS(c->c_lock) : NULL; 631 lock_status = 0; 632 if (c->c_flags & CALLOUT_SHAREDLOCK) { 633 if (class == &lock_class_rm) 634 lock_status = (uintptr_t)&tracker; 635 else 636 lock_status = 1; 637 } 638 c_lock = c->c_lock; 639 c_func = c->c_func; 640 c_arg = c->c_arg; 641 c_iflags = c->c_iflags; 642 if (c->c_iflags & CALLOUT_LOCAL_ALLOC) 643 c->c_iflags = CALLOUT_LOCAL_ALLOC; 644 else 645 c->c_iflags &= ~CALLOUT_PENDING; 646 647 cc_exec_curr(cc, direct) = c; 648 cc_exec_cancel(cc, direct) = false; 649 CC_UNLOCK(cc); 650 if (c_lock != NULL) { 651 class->lc_lock(c_lock, lock_status); 652 /* 653 * The callout may have been cancelled 654 * while we switched locks. 655 */ 656 if (cc_exec_cancel(cc, direct)) { 657 class->lc_unlock(c_lock); 658 goto skip; 659 } 660 /* The callout cannot be stopped now. */ 661 cc_exec_cancel(cc, direct) = true; 662 if (c_lock == &Giant.lock_object) { 663 #ifdef CALLOUT_PROFILING 664 (*gcalls)++; 665 #endif 666 CTR3(KTR_CALLOUT, "callout giant %p func %p arg %p", 667 c, c_func, c_arg); 668 } else { 669 #ifdef CALLOUT_PROFILING 670 (*lockcalls)++; 671 #endif 672 CTR3(KTR_CALLOUT, "callout lock %p func %p arg %p", 673 c, c_func, c_arg); 674 } 675 } else { 676 #ifdef CALLOUT_PROFILING 677 (*mpcalls)++; 678 #endif 679 CTR3(KTR_CALLOUT, "callout %p func %p arg %p", 680 c, c_func, c_arg); 681 } 682 KTR_STATE3(KTR_SCHED, "callout", cc->cc_ktr_event_name, "running", 683 "func:%p", c_func, "arg:%p", c_arg, "direct:%d", direct); 684 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING) 685 sbt1 = sbinuptime(); 686 #endif 687 THREAD_NO_SLEEPING(); 688 SDT_PROBE1(callout_execute, , , callout__start, c); 689 c_func(c_arg); 690 SDT_PROBE1(callout_execute, , , callout__end, c); 691 THREAD_SLEEPING_OK(); 692 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING) 693 sbt2 = sbinuptime(); 694 sbt2 -= sbt1; 695 if (sbt2 > maxdt) { 696 if (lastfunc != c_func || sbt2 > maxdt * 2) { 697 ts2 = sbttots(sbt2); 698 printf( 699 "Expensive timeout(9) function: %p(%p) %jd.%09ld s\n", 700 c_func, c_arg, (intmax_t)ts2.tv_sec, ts2.tv_nsec); 701 } 702 maxdt = sbt2; 703 lastfunc = c_func; 704 } 705 #endif 706 KTR_STATE0(KTR_SCHED, "callout", cc->cc_ktr_event_name, "idle"); 707 CTR1(KTR_CALLOUT, "callout %p finished", c); 708 if ((c_iflags & CALLOUT_RETURNUNLOCKED) == 0) 709 class->lc_unlock(c_lock); 710 skip: 711 CC_LOCK(cc); 712 KASSERT(cc_exec_curr(cc, direct) == c, ("mishandled cc_curr")); 713 cc_exec_curr(cc, direct) = NULL; 714 if (cc_exec_waiting(cc, direct)) { 715 /* 716 * There is someone waiting for the 717 * callout to complete. 718 * If the callout was scheduled for 719 * migration just cancel it. 720 */ 721 if (cc_cce_migrating(cc, direct)) { 722 cc_cce_cleanup(cc, direct); 723 724 /* 725 * It should be assert here that the callout is not 726 * destroyed but that is not easy. 727 */ 728 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 729 } 730 cc_exec_waiting(cc, direct) = false; 731 CC_UNLOCK(cc); 732 wakeup(&cc_exec_waiting(cc, direct)); 733 CC_LOCK(cc); 734 } else if (cc_cce_migrating(cc, direct)) { 735 KASSERT((c_iflags & CALLOUT_LOCAL_ALLOC) == 0, 736 ("Migrating legacy callout %p", c)); 737 #ifdef SMP 738 /* 739 * If the callout was scheduled for 740 * migration just perform it now. 741 */ 742 new_cpu = cc_migration_cpu(cc, direct); 743 new_time = cc_migration_time(cc, direct); 744 new_prec = cc_migration_prec(cc, direct); 745 new_func = cc_migration_func(cc, direct); 746 new_arg = cc_migration_arg(cc, direct); 747 cc_cce_cleanup(cc, direct); 748 749 /* 750 * It should be assert here that the callout is not destroyed 751 * but that is not easy. 752 * 753 * As first thing, handle deferred callout stops. 754 */ 755 if (!callout_migrating(c)) { 756 CTR3(KTR_CALLOUT, 757 "deferred cancelled %p func %p arg %p", 758 c, new_func, new_arg); 759 callout_cc_del(c, cc); 760 return; 761 } 762 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 763 764 new_cc = callout_cpu_switch(c, cc, new_cpu); 765 flags = (direct) ? C_DIRECT_EXEC : 0; 766 callout_cc_add(c, new_cc, new_time, new_prec, new_func, 767 new_arg, new_cpu, flags); 768 CC_UNLOCK(new_cc); 769 CC_LOCK(cc); 770 #else 771 panic("migration should not happen"); 772 #endif 773 } 774 /* 775 * If the current callout is locally allocated (from 776 * timeout(9)) then put it on the freelist. 777 * 778 * Note: we need to check the cached copy of c_iflags because 779 * if it was not local, then it's not safe to deref the 780 * callout pointer. 781 */ 782 KASSERT((c_iflags & CALLOUT_LOCAL_ALLOC) == 0 || 783 c->c_iflags == CALLOUT_LOCAL_ALLOC, 784 ("corrupted callout")); 785 if (c_iflags & CALLOUT_LOCAL_ALLOC) 786 callout_cc_del(c, cc); 787 } 788 789 /* 790 * The callout mechanism is based on the work of Adam M. Costello and 791 * George Varghese, published in a technical report entitled "Redesigning 792 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 793 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 794 * used in this implementation was published by G. Varghese and T. Lauck in 795 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 796 * the Efficient Implementation of a Timer Facility" in the Proceedings of 797 * the 11th ACM Annual Symposium on Operating Systems Principles, 798 * Austin, Texas Nov 1987. 799 */ 800 801 /* 802 * Software (low priority) clock interrupt. 803 * Run periodic events from timeout queue. 804 */ 805 void 806 softclock(void *arg) 807 { 808 struct callout_cpu *cc; 809 struct callout *c; 810 #ifdef CALLOUT_PROFILING 811 int depth = 0, gcalls = 0, lockcalls = 0, mpcalls = 0; 812 #endif 813 814 cc = (struct callout_cpu *)arg; 815 CC_LOCK(cc); 816 while ((c = TAILQ_FIRST(&cc->cc_expireq)) != NULL) { 817 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe); 818 softclock_call_cc(c, cc, 819 #ifdef CALLOUT_PROFILING 820 &mpcalls, &lockcalls, &gcalls, 821 #endif 822 0); 823 #ifdef CALLOUT_PROFILING 824 ++depth; 825 #endif 826 } 827 #ifdef CALLOUT_PROFILING 828 avg_depth += (depth * 1000 - avg_depth) >> 8; 829 avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8; 830 avg_lockcalls += (lockcalls * 1000 - avg_lockcalls) >> 8; 831 avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8; 832 #endif 833 CC_UNLOCK(cc); 834 } 835 836 /* 837 * timeout -- 838 * Execute a function after a specified length of time. 839 * 840 * untimeout -- 841 * Cancel previous timeout function call. 842 * 843 * callout_handle_init -- 844 * Initialize a handle so that using it with untimeout is benign. 845 * 846 * See AT&T BCI Driver Reference Manual for specification. This 847 * implementation differs from that one in that although an 848 * identification value is returned from timeout, the original 849 * arguments to timeout as well as the identifier are used to 850 * identify entries for untimeout. 851 */ 852 struct callout_handle 853 timeout(ftn, arg, to_ticks) 854 timeout_t *ftn; 855 void *arg; 856 int to_ticks; 857 { 858 struct callout_cpu *cc; 859 struct callout *new; 860 struct callout_handle handle; 861 862 cc = CC_CPU(timeout_cpu); 863 CC_LOCK(cc); 864 /* Fill in the next free callout structure. */ 865 new = SLIST_FIRST(&cc->cc_callfree); 866 if (new == NULL) 867 /* XXX Attempt to malloc first */ 868 panic("timeout table full"); 869 SLIST_REMOVE_HEAD(&cc->cc_callfree, c_links.sle); 870 callout_reset(new, to_ticks, ftn, arg); 871 handle.callout = new; 872 CC_UNLOCK(cc); 873 874 return (handle); 875 } 876 877 void 878 untimeout(ftn, arg, handle) 879 timeout_t *ftn; 880 void *arg; 881 struct callout_handle handle; 882 { 883 struct callout_cpu *cc; 884 885 /* 886 * Check for a handle that was initialized 887 * by callout_handle_init, but never used 888 * for a real timeout. 889 */ 890 if (handle.callout == NULL) 891 return; 892 893 cc = callout_lock(handle.callout); 894 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 895 callout_stop(handle.callout); 896 CC_UNLOCK(cc); 897 } 898 899 void 900 callout_handle_init(struct callout_handle *handle) 901 { 902 handle->callout = NULL; 903 } 904 905 void 906 callout_when(sbintime_t sbt, sbintime_t precision, int flags, 907 sbintime_t *res, sbintime_t *prec_res) 908 { 909 sbintime_t to_sbt, to_pr; 910 911 if ((flags & (C_ABSOLUTE | C_PRECALC)) != 0) { 912 *res = sbt; 913 *prec_res = precision; 914 return; 915 } 916 if ((flags & C_HARDCLOCK) != 0 && sbt < tick_sbt) 917 sbt = tick_sbt; 918 if ((flags & C_HARDCLOCK) != 0 || 919 #ifdef NO_EVENTTIMERS 920 sbt >= sbt_timethreshold) { 921 to_sbt = getsbinuptime(); 922 923 /* Add safety belt for the case of hz > 1000. */ 924 to_sbt += tc_tick_sbt - tick_sbt; 925 #else 926 sbt >= sbt_tickthreshold) { 927 /* 928 * Obtain the time of the last hardclock() call on 929 * this CPU directly from the kern_clocksource.c. 930 * This value is per-CPU, but it is equal for all 931 * active ones. 932 */ 933 #ifdef __LP64__ 934 to_sbt = DPCPU_GET(hardclocktime); 935 #else 936 spinlock_enter(); 937 to_sbt = DPCPU_GET(hardclocktime); 938 spinlock_exit(); 939 #endif 940 #endif 941 if ((flags & C_HARDCLOCK) == 0) 942 to_sbt += tick_sbt; 943 } else 944 to_sbt = sbinuptime(); 945 if (SBT_MAX - to_sbt < sbt) 946 to_sbt = SBT_MAX; 947 else 948 to_sbt += sbt; 949 *res = to_sbt; 950 to_pr = ((C_PRELGET(flags) < 0) ? sbt >> tc_precexp : 951 sbt >> C_PRELGET(flags)); 952 *prec_res = to_pr > precision ? to_pr : precision; 953 } 954 955 /* 956 * New interface; clients allocate their own callout structures. 957 * 958 * callout_reset() - establish or change a timeout 959 * callout_stop() - disestablish a timeout 960 * callout_init() - initialize a callout structure so that it can 961 * safely be passed to callout_reset() and callout_stop() 962 * 963 * <sys/callout.h> defines three convenience macros: 964 * 965 * callout_active() - returns truth if callout has not been stopped, 966 * drained, or deactivated since the last time the callout was 967 * reset. 968 * callout_pending() - returns truth if callout is still waiting for timeout 969 * callout_deactivate() - marks the callout as having been serviced 970 */ 971 int 972 callout_reset_sbt_on(struct callout *c, sbintime_t sbt, sbintime_t prec, 973 void (*ftn)(void *), void *arg, int cpu, int flags) 974 { 975 sbintime_t to_sbt, precision; 976 struct callout_cpu *cc; 977 int cancelled, direct; 978 int ignore_cpu=0; 979 980 cancelled = 0; 981 if (cpu == -1) { 982 ignore_cpu = 1; 983 } else if ((cpu >= MAXCPU) || 984 ((CC_CPU(cpu))->cc_inited == 0)) { 985 /* Invalid CPU spec */ 986 panic("Invalid CPU in callout %d", cpu); 987 } 988 callout_when(sbt, prec, flags, &to_sbt, &precision); 989 990 /* 991 * This flag used to be added by callout_cc_add, but the 992 * first time you call this we could end up with the 993 * wrong direct flag if we don't do it before we add. 994 */ 995 if (flags & C_DIRECT_EXEC) { 996 direct = 1; 997 } else { 998 direct = 0; 999 } 1000 KASSERT(!direct || c->c_lock == NULL, 1001 ("%s: direct callout %p has lock", __func__, c)); 1002 cc = callout_lock(c); 1003 /* 1004 * Don't allow migration of pre-allocated callouts lest they 1005 * become unbalanced or handle the case where the user does 1006 * not care. 1007 */ 1008 if ((c->c_iflags & CALLOUT_LOCAL_ALLOC) || 1009 ignore_cpu) { 1010 cpu = c->c_cpu; 1011 } 1012 1013 if (cc_exec_curr(cc, direct) == c) { 1014 /* 1015 * We're being asked to reschedule a callout which is 1016 * currently in progress. If there is a lock then we 1017 * can cancel the callout if it has not really started. 1018 */ 1019 if (c->c_lock != NULL && !cc_exec_cancel(cc, direct)) 1020 cancelled = cc_exec_cancel(cc, direct) = true; 1021 if (cc_exec_waiting(cc, direct)) { 1022 /* 1023 * Someone has called callout_drain to kill this 1024 * callout. Don't reschedule. 1025 */ 1026 CTR4(KTR_CALLOUT, "%s %p func %p arg %p", 1027 cancelled ? "cancelled" : "failed to cancel", 1028 c, c->c_func, c->c_arg); 1029 CC_UNLOCK(cc); 1030 return (cancelled); 1031 } 1032 #ifdef SMP 1033 if (callout_migrating(c)) { 1034 /* 1035 * This only occurs when a second callout_reset_sbt_on 1036 * is made after a previous one moved it into 1037 * deferred migration (below). Note we do *not* change 1038 * the prev_cpu even though the previous target may 1039 * be different. 1040 */ 1041 cc_migration_cpu(cc, direct) = cpu; 1042 cc_migration_time(cc, direct) = to_sbt; 1043 cc_migration_prec(cc, direct) = precision; 1044 cc_migration_func(cc, direct) = ftn; 1045 cc_migration_arg(cc, direct) = arg; 1046 cancelled = 1; 1047 CC_UNLOCK(cc); 1048 return (cancelled); 1049 } 1050 #endif 1051 } 1052 if (c->c_iflags & CALLOUT_PENDING) { 1053 if ((c->c_iflags & CALLOUT_PROCESSED) == 0) { 1054 if (cc_exec_next(cc) == c) 1055 cc_exec_next(cc) = LIST_NEXT(c, c_links.le); 1056 LIST_REMOVE(c, c_links.le); 1057 } else { 1058 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe); 1059 } 1060 cancelled = 1; 1061 c->c_iflags &= ~ CALLOUT_PENDING; 1062 c->c_flags &= ~ CALLOUT_ACTIVE; 1063 } 1064 1065 #ifdef SMP 1066 /* 1067 * If the callout must migrate try to perform it immediately. 1068 * If the callout is currently running, just defer the migration 1069 * to a more appropriate moment. 1070 */ 1071 if (c->c_cpu != cpu) { 1072 if (cc_exec_curr(cc, direct) == c) { 1073 /* 1074 * Pending will have been removed since we are 1075 * actually executing the callout on another 1076 * CPU. That callout should be waiting on the 1077 * lock the caller holds. If we set both 1078 * active/and/pending after we return and the 1079 * lock on the executing callout proceeds, it 1080 * will then see pending is true and return. 1081 * At the return from the actual callout execution 1082 * the migration will occur in softclock_call_cc 1083 * and this new callout will be placed on the 1084 * new CPU via a call to callout_cpu_switch() which 1085 * will get the lock on the right CPU followed 1086 * by a call callout_cc_add() which will add it there. 1087 * (see above in softclock_call_cc()). 1088 */ 1089 cc_migration_cpu(cc, direct) = cpu; 1090 cc_migration_time(cc, direct) = to_sbt; 1091 cc_migration_prec(cc, direct) = precision; 1092 cc_migration_func(cc, direct) = ftn; 1093 cc_migration_arg(cc, direct) = arg; 1094 c->c_iflags |= (CALLOUT_DFRMIGRATION | CALLOUT_PENDING); 1095 c->c_flags |= CALLOUT_ACTIVE; 1096 CTR6(KTR_CALLOUT, 1097 "migration of %p func %p arg %p in %d.%08x to %u deferred", 1098 c, c->c_func, c->c_arg, (int)(to_sbt >> 32), 1099 (u_int)(to_sbt & 0xffffffff), cpu); 1100 CC_UNLOCK(cc); 1101 return (cancelled); 1102 } 1103 cc = callout_cpu_switch(c, cc, cpu); 1104 } 1105 #endif 1106 1107 callout_cc_add(c, cc, to_sbt, precision, ftn, arg, cpu, flags); 1108 CTR6(KTR_CALLOUT, "%sscheduled %p func %p arg %p in %d.%08x", 1109 cancelled ? "re" : "", c, c->c_func, c->c_arg, (int)(to_sbt >> 32), 1110 (u_int)(to_sbt & 0xffffffff)); 1111 CC_UNLOCK(cc); 1112 1113 return (cancelled); 1114 } 1115 1116 /* 1117 * Common idioms that can be optimized in the future. 1118 */ 1119 int 1120 callout_schedule_on(struct callout *c, int to_ticks, int cpu) 1121 { 1122 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, cpu); 1123 } 1124 1125 int 1126 callout_schedule(struct callout *c, int to_ticks) 1127 { 1128 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, c->c_cpu); 1129 } 1130 1131 int 1132 _callout_stop_safe(c, flags) 1133 struct callout *c; 1134 int flags; 1135 { 1136 struct callout_cpu *cc, *old_cc; 1137 struct lock_class *class; 1138 int direct, sq_locked, use_lock; 1139 int not_on_a_list; 1140 1141 /* 1142 * Some old subsystems don't hold Giant while running a callout_stop(), 1143 * so just discard this check for the moment. 1144 */ 1145 if ((flags & CS_DRAIN) == 0 && c->c_lock != NULL) { 1146 if (c->c_lock == &Giant.lock_object) 1147 use_lock = mtx_owned(&Giant); 1148 else { 1149 use_lock = 1; 1150 class = LOCK_CLASS(c->c_lock); 1151 class->lc_assert(c->c_lock, LA_XLOCKED); 1152 } 1153 } else 1154 use_lock = 0; 1155 if (c->c_iflags & CALLOUT_DIRECT) { 1156 direct = 1; 1157 } else { 1158 direct = 0; 1159 } 1160 sq_locked = 0; 1161 old_cc = NULL; 1162 again: 1163 cc = callout_lock(c); 1164 1165 if ((c->c_iflags & (CALLOUT_DFRMIGRATION | CALLOUT_PENDING)) == 1166 (CALLOUT_DFRMIGRATION | CALLOUT_PENDING) && 1167 ((c->c_flags & CALLOUT_ACTIVE) == CALLOUT_ACTIVE)) { 1168 /* 1169 * Special case where this slipped in while we 1170 * were migrating *as* the callout is about to 1171 * execute. The caller probably holds the lock 1172 * the callout wants. 1173 * 1174 * Get rid of the migration first. Then set 1175 * the flag that tells this code *not* to 1176 * try to remove it from any lists (its not 1177 * on one yet). When the callout wheel runs, 1178 * it will ignore this callout. 1179 */ 1180 c->c_iflags &= ~CALLOUT_PENDING; 1181 c->c_flags &= ~CALLOUT_ACTIVE; 1182 not_on_a_list = 1; 1183 } else { 1184 not_on_a_list = 0; 1185 } 1186 1187 /* 1188 * If the callout was migrating while the callout cpu lock was 1189 * dropped, just drop the sleepqueue lock and check the states 1190 * again. 1191 */ 1192 if (sq_locked != 0 && cc != old_cc) { 1193 #ifdef SMP 1194 CC_UNLOCK(cc); 1195 sleepq_release(&cc_exec_waiting(old_cc, direct)); 1196 sq_locked = 0; 1197 old_cc = NULL; 1198 goto again; 1199 #else 1200 panic("migration should not happen"); 1201 #endif 1202 } 1203 1204 /* 1205 * If the callout isn't pending, it's not on the queue, so 1206 * don't attempt to remove it from the queue. We can try to 1207 * stop it by other means however. 1208 */ 1209 if (!(c->c_iflags & CALLOUT_PENDING)) { 1210 c->c_flags &= ~CALLOUT_ACTIVE; 1211 1212 /* 1213 * If it wasn't on the queue and it isn't the current 1214 * callout, then we can't stop it, so just bail. 1215 */ 1216 if (cc_exec_curr(cc, direct) != c) { 1217 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 1218 c, c->c_func, c->c_arg); 1219 CC_UNLOCK(cc); 1220 if (sq_locked) 1221 sleepq_release(&cc_exec_waiting(cc, direct)); 1222 return (0); 1223 } 1224 1225 if ((flags & CS_DRAIN) != 0) { 1226 /* 1227 * The current callout is running (or just 1228 * about to run) and blocking is allowed, so 1229 * just wait for the current invocation to 1230 * finish. 1231 */ 1232 while (cc_exec_curr(cc, direct) == c) { 1233 /* 1234 * Use direct calls to sleepqueue interface 1235 * instead of cv/msleep in order to avoid 1236 * a LOR between cc_lock and sleepqueue 1237 * chain spinlocks. This piece of code 1238 * emulates a msleep_spin() call actually. 1239 * 1240 * If we already have the sleepqueue chain 1241 * locked, then we can safely block. If we 1242 * don't already have it locked, however, 1243 * we have to drop the cc_lock to lock 1244 * it. This opens several races, so we 1245 * restart at the beginning once we have 1246 * both locks. If nothing has changed, then 1247 * we will end up back here with sq_locked 1248 * set. 1249 */ 1250 if (!sq_locked) { 1251 CC_UNLOCK(cc); 1252 sleepq_lock( 1253 &cc_exec_waiting(cc, direct)); 1254 sq_locked = 1; 1255 old_cc = cc; 1256 goto again; 1257 } 1258 1259 /* 1260 * Migration could be cancelled here, but 1261 * as long as it is still not sure when it 1262 * will be packed up, just let softclock() 1263 * take care of it. 1264 */ 1265 cc_exec_waiting(cc, direct) = true; 1266 DROP_GIANT(); 1267 CC_UNLOCK(cc); 1268 sleepq_add( 1269 &cc_exec_waiting(cc, direct), 1270 &cc->cc_lock.lock_object, "codrain", 1271 SLEEPQ_SLEEP, 0); 1272 sleepq_wait( 1273 &cc_exec_waiting(cc, direct), 1274 0); 1275 sq_locked = 0; 1276 old_cc = NULL; 1277 1278 /* Reacquire locks previously released. */ 1279 PICKUP_GIANT(); 1280 CC_LOCK(cc); 1281 } 1282 } else if (use_lock && 1283 !cc_exec_cancel(cc, direct)) { 1284 1285 /* 1286 * The current callout is waiting for its 1287 * lock which we hold. Cancel the callout 1288 * and return. After our caller drops the 1289 * lock, the callout will be skipped in 1290 * softclock(). 1291 */ 1292 cc_exec_cancel(cc, direct) = true; 1293 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 1294 c, c->c_func, c->c_arg); 1295 KASSERT(!cc_cce_migrating(cc, direct), 1296 ("callout wrongly scheduled for migration")); 1297 if (callout_migrating(c)) { 1298 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 1299 #ifdef SMP 1300 cc_migration_cpu(cc, direct) = CPUBLOCK; 1301 cc_migration_time(cc, direct) = 0; 1302 cc_migration_prec(cc, direct) = 0; 1303 cc_migration_func(cc, direct) = NULL; 1304 cc_migration_arg(cc, direct) = NULL; 1305 #endif 1306 } 1307 CC_UNLOCK(cc); 1308 KASSERT(!sq_locked, ("sleepqueue chain locked")); 1309 return (1); 1310 } else if (callout_migrating(c)) { 1311 /* 1312 * The callout is currently being serviced 1313 * and the "next" callout is scheduled at 1314 * its completion with a migration. We remove 1315 * the migration flag so it *won't* get rescheduled, 1316 * but we can't stop the one thats running so 1317 * we return 0. 1318 */ 1319 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 1320 #ifdef SMP 1321 /* 1322 * We can't call cc_cce_cleanup here since 1323 * if we do it will remove .ce_curr and 1324 * its still running. This will prevent a 1325 * reschedule of the callout when the 1326 * execution completes. 1327 */ 1328 cc_migration_cpu(cc, direct) = CPUBLOCK; 1329 cc_migration_time(cc, direct) = 0; 1330 cc_migration_prec(cc, direct) = 0; 1331 cc_migration_func(cc, direct) = NULL; 1332 cc_migration_arg(cc, direct) = NULL; 1333 #endif 1334 CTR3(KTR_CALLOUT, "postponing stop %p func %p arg %p", 1335 c, c->c_func, c->c_arg); 1336 CC_UNLOCK(cc); 1337 return ((flags & CS_MIGRBLOCK) != 0); 1338 } 1339 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 1340 c, c->c_func, c->c_arg); 1341 CC_UNLOCK(cc); 1342 KASSERT(!sq_locked, ("sleepqueue chain still locked")); 1343 return (0); 1344 } 1345 if (sq_locked) 1346 sleepq_release(&cc_exec_waiting(cc, direct)); 1347 1348 c->c_iflags &= ~CALLOUT_PENDING; 1349 c->c_flags &= ~CALLOUT_ACTIVE; 1350 1351 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 1352 c, c->c_func, c->c_arg); 1353 if (not_on_a_list == 0) { 1354 if ((c->c_iflags & CALLOUT_PROCESSED) == 0) { 1355 if (cc_exec_next(cc) == c) 1356 cc_exec_next(cc) = LIST_NEXT(c, c_links.le); 1357 LIST_REMOVE(c, c_links.le); 1358 } else { 1359 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe); 1360 } 1361 } 1362 callout_cc_del(c, cc); 1363 CC_UNLOCK(cc); 1364 return (1); 1365 } 1366 1367 void 1368 callout_init(c, mpsafe) 1369 struct callout *c; 1370 int mpsafe; 1371 { 1372 bzero(c, sizeof *c); 1373 if (mpsafe) { 1374 c->c_lock = NULL; 1375 c->c_iflags = CALLOUT_RETURNUNLOCKED; 1376 } else { 1377 c->c_lock = &Giant.lock_object; 1378 c->c_iflags = 0; 1379 } 1380 c->c_cpu = timeout_cpu; 1381 } 1382 1383 void 1384 _callout_init_lock(c, lock, flags) 1385 struct callout *c; 1386 struct lock_object *lock; 1387 int flags; 1388 { 1389 bzero(c, sizeof *c); 1390 c->c_lock = lock; 1391 KASSERT((flags & ~(CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK)) == 0, 1392 ("callout_init_lock: bad flags %d", flags)); 1393 KASSERT(lock != NULL || (flags & CALLOUT_RETURNUNLOCKED) == 0, 1394 ("callout_init_lock: CALLOUT_RETURNUNLOCKED with no lock")); 1395 KASSERT(lock == NULL || !(LOCK_CLASS(lock)->lc_flags & 1396 (LC_SPINLOCK | LC_SLEEPABLE)), ("%s: invalid lock class", 1397 __func__)); 1398 c->c_iflags = flags & (CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK); 1399 c->c_cpu = timeout_cpu; 1400 } 1401 1402 #ifdef APM_FIXUP_CALLTODO 1403 /* 1404 * Adjust the kernel calltodo timeout list. This routine is used after 1405 * an APM resume to recalculate the calltodo timer list values with the 1406 * number of hz's we have been sleeping. The next hardclock() will detect 1407 * that there are fired timers and run softclock() to execute them. 1408 * 1409 * Please note, I have not done an exhaustive analysis of what code this 1410 * might break. I am motivated to have my select()'s and alarm()'s that 1411 * have expired during suspend firing upon resume so that the applications 1412 * which set the timer can do the maintanence the timer was for as close 1413 * as possible to the originally intended time. Testing this code for a 1414 * week showed that resuming from a suspend resulted in 22 to 25 timers 1415 * firing, which seemed independent on whether the suspend was 2 hours or 1416 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 1417 */ 1418 void 1419 adjust_timeout_calltodo(time_change) 1420 struct timeval *time_change; 1421 { 1422 register struct callout *p; 1423 unsigned long delta_ticks; 1424 1425 /* 1426 * How many ticks were we asleep? 1427 * (stolen from tvtohz()). 1428 */ 1429 1430 /* Don't do anything */ 1431 if (time_change->tv_sec < 0) 1432 return; 1433 else if (time_change->tv_sec <= LONG_MAX / 1000000) 1434 delta_ticks = (time_change->tv_sec * 1000000 + 1435 time_change->tv_usec + (tick - 1)) / tick + 1; 1436 else if (time_change->tv_sec <= LONG_MAX / hz) 1437 delta_ticks = time_change->tv_sec * hz + 1438 (time_change->tv_usec + (tick - 1)) / tick + 1; 1439 else 1440 delta_ticks = LONG_MAX; 1441 1442 if (delta_ticks > INT_MAX) 1443 delta_ticks = INT_MAX; 1444 1445 /* 1446 * Now rip through the timer calltodo list looking for timers 1447 * to expire. 1448 */ 1449 1450 /* don't collide with softclock() */ 1451 CC_LOCK(cc); 1452 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 1453 p->c_time -= delta_ticks; 1454 1455 /* Break if the timer had more time on it than delta_ticks */ 1456 if (p->c_time > 0) 1457 break; 1458 1459 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 1460 delta_ticks = -p->c_time; 1461 } 1462 CC_UNLOCK(cc); 1463 1464 return; 1465 } 1466 #endif /* APM_FIXUP_CALLTODO */ 1467 1468 static int 1469 flssbt(sbintime_t sbt) 1470 { 1471 1472 sbt += (uint64_t)sbt >> 1; 1473 if (sizeof(long) >= sizeof(sbintime_t)) 1474 return (flsl(sbt)); 1475 if (sbt >= SBT_1S) 1476 return (flsl(((uint64_t)sbt) >> 32) + 32); 1477 return (flsl(sbt)); 1478 } 1479 1480 /* 1481 * Dump immediate statistic snapshot of the scheduled callouts. 1482 */ 1483 static int 1484 sysctl_kern_callout_stat(SYSCTL_HANDLER_ARGS) 1485 { 1486 struct callout *tmp; 1487 struct callout_cpu *cc; 1488 struct callout_list *sc; 1489 sbintime_t maxpr, maxt, medpr, medt, now, spr, st, t; 1490 int ct[64], cpr[64], ccpbk[32]; 1491 int error, val, i, count, tcum, pcum, maxc, c, medc; 1492 #ifdef SMP 1493 int cpu; 1494 #endif 1495 1496 val = 0; 1497 error = sysctl_handle_int(oidp, &val, 0, req); 1498 if (error != 0 || req->newptr == NULL) 1499 return (error); 1500 count = maxc = 0; 1501 st = spr = maxt = maxpr = 0; 1502 bzero(ccpbk, sizeof(ccpbk)); 1503 bzero(ct, sizeof(ct)); 1504 bzero(cpr, sizeof(cpr)); 1505 now = sbinuptime(); 1506 #ifdef SMP 1507 CPU_FOREACH(cpu) { 1508 cc = CC_CPU(cpu); 1509 #else 1510 cc = CC_CPU(timeout_cpu); 1511 #endif 1512 CC_LOCK(cc); 1513 for (i = 0; i < callwheelsize; i++) { 1514 sc = &cc->cc_callwheel[i]; 1515 c = 0; 1516 LIST_FOREACH(tmp, sc, c_links.le) { 1517 c++; 1518 t = tmp->c_time - now; 1519 if (t < 0) 1520 t = 0; 1521 st += t / SBT_1US; 1522 spr += tmp->c_precision / SBT_1US; 1523 if (t > maxt) 1524 maxt = t; 1525 if (tmp->c_precision > maxpr) 1526 maxpr = tmp->c_precision; 1527 ct[flssbt(t)]++; 1528 cpr[flssbt(tmp->c_precision)]++; 1529 } 1530 if (c > maxc) 1531 maxc = c; 1532 ccpbk[fls(c + c / 2)]++; 1533 count += c; 1534 } 1535 CC_UNLOCK(cc); 1536 #ifdef SMP 1537 } 1538 #endif 1539 1540 for (i = 0, tcum = 0; i < 64 && tcum < count / 2; i++) 1541 tcum += ct[i]; 1542 medt = (i >= 2) ? (((sbintime_t)1) << (i - 2)) : 0; 1543 for (i = 0, pcum = 0; i < 64 && pcum < count / 2; i++) 1544 pcum += cpr[i]; 1545 medpr = (i >= 2) ? (((sbintime_t)1) << (i - 2)) : 0; 1546 for (i = 0, c = 0; i < 32 && c < count / 2; i++) 1547 c += ccpbk[i]; 1548 medc = (i >= 2) ? (1 << (i - 2)) : 0; 1549 1550 printf("Scheduled callouts statistic snapshot:\n"); 1551 printf(" Callouts: %6d Buckets: %6d*%-3d Bucket size: 0.%06ds\n", 1552 count, callwheelsize, mp_ncpus, 1000000 >> CC_HASH_SHIFT); 1553 printf(" C/Bk: med %5d avg %6d.%06jd max %6d\n", 1554 medc, 1555 count / callwheelsize / mp_ncpus, 1556 (uint64_t)count * 1000000 / callwheelsize / mp_ncpus % 1000000, 1557 maxc); 1558 printf(" Time: med %5jd.%06jds avg %6jd.%06jds max %6jd.%06jds\n", 1559 medt / SBT_1S, (medt & 0xffffffff) * 1000000 >> 32, 1560 (st / count) / 1000000, (st / count) % 1000000, 1561 maxt / SBT_1S, (maxt & 0xffffffff) * 1000000 >> 32); 1562 printf(" Prec: med %5jd.%06jds avg %6jd.%06jds max %6jd.%06jds\n", 1563 medpr / SBT_1S, (medpr & 0xffffffff) * 1000000 >> 32, 1564 (spr / count) / 1000000, (spr / count) % 1000000, 1565 maxpr / SBT_1S, (maxpr & 0xffffffff) * 1000000 >> 32); 1566 printf(" Distribution: \tbuckets\t time\t tcum\t" 1567 " prec\t pcum\n"); 1568 for (i = 0, tcum = pcum = 0; i < 64; i++) { 1569 if (ct[i] == 0 && cpr[i] == 0) 1570 continue; 1571 t = (i != 0) ? (((sbintime_t)1) << (i - 1)) : 0; 1572 tcum += ct[i]; 1573 pcum += cpr[i]; 1574 printf(" %10jd.%06jds\t 2**%d\t%7d\t%7d\t%7d\t%7d\n", 1575 t / SBT_1S, (t & 0xffffffff) * 1000000 >> 32, 1576 i - 1 - (32 - CC_HASH_SHIFT), 1577 ct[i], tcum, cpr[i], pcum); 1578 } 1579 return (error); 1580 } 1581 SYSCTL_PROC(_kern, OID_AUTO, callout_stat, 1582 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, 1583 0, 0, sysctl_kern_callout_stat, "I", 1584 "Dump immediate statistic snapshot of the scheduled callouts"); 1585 1586 #ifdef DDB 1587 static void 1588 _show_callout(struct callout *c) 1589 { 1590 1591 db_printf("callout %p\n", c); 1592 #define C_DB_PRINTF(f, e) db_printf(" %s = " f "\n", #e, c->e); 1593 db_printf(" &c_links = %p\n", &(c->c_links)); 1594 C_DB_PRINTF("%" PRId64, c_time); 1595 C_DB_PRINTF("%" PRId64, c_precision); 1596 C_DB_PRINTF("%p", c_arg); 1597 C_DB_PRINTF("%p", c_func); 1598 C_DB_PRINTF("%p", c_lock); 1599 C_DB_PRINTF("%#x", c_flags); 1600 C_DB_PRINTF("%#x", c_iflags); 1601 C_DB_PRINTF("%d", c_cpu); 1602 #undef C_DB_PRINTF 1603 } 1604 1605 DB_SHOW_COMMAND(callout, db_show_callout) 1606 { 1607 1608 if (!have_addr) { 1609 db_printf("usage: show callout <struct callout *>\n"); 1610 return; 1611 } 1612 1613 _show_callout((struct callout *)addr); 1614 } 1615 #endif /* DDB */
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