kern_timeout.c revision 209059
1275988Sngie/*- 2240116Smarcel * Copyright (c) 1982, 1986, 1991, 1993 3240116Smarcel * The Regents of the University of California. All rights reserved. 4240116Smarcel * (c) UNIX System Laboratories, Inc. 5240116Smarcel * All or some portions of this file are derived from material licensed 6240116Smarcel * to the University of California by American Telephone and Telegraph 7240116Smarcel * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8240116Smarcel * the permission of UNIX System Laboratories, Inc. 9240116Smarcel * 10240116Smarcel * Redistribution and use in source and binary forms, with or without 11240116Smarcel * modification, are permitted provided that the following conditions 12240116Smarcel * are met: 13240116Smarcel * 1. Redistributions of source code must retain the above copyright 14240116Smarcel * notice, this list of conditions and the following disclaimer. 15240116Smarcel * 2. Redistributions in binary form must reproduce the above copyright 16240116Smarcel * notice, this list of conditions and the following disclaimer in the 17240116Smarcel * documentation and/or other materials provided with the distribution. 18240116Smarcel * 4. Neither the name of the University nor the names of its contributors 19240116Smarcel * may be used to endorse or promote products derived from this software 20240116Smarcel * without specific prior written permission. 21240116Smarcel * 22240116Smarcel * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23240116Smarcel * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24275988Sngie * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25240116Smarcel * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26240116Smarcel * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27240116Smarcel * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28240116Smarcel * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29240116Smarcel * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30240116Smarcel * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31240116Smarcel * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32240116Smarcel * SUCH DAMAGE. 33240116Smarcel * 34240116Smarcel * From: @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 35240116Smarcel */ 36240116Smarcel 37240116Smarcel#include <sys/cdefs.h> 38240116Smarcel__FBSDID("$FreeBSD: head/sys/kern/kern_timeout.c 209059 2010-06-11 18:46:34Z jhb $"); 39240116Smarcel 40240116Smarcel#include "opt_kdtrace.h" 41240116Smarcel 42240116Smarcel#include <sys/param.h> 43240116Smarcel#include <sys/systm.h> 44240116Smarcel#include <sys/bus.h> 45240116Smarcel#include <sys/callout.h> 46240116Smarcel#include <sys/condvar.h> 47240116Smarcel#include <sys/interrupt.h> 48240116Smarcel#include <sys/kernel.h> 49240116Smarcel#include <sys/ktr.h> 50240116Smarcel#include <sys/lock.h> 51240116Smarcel#include <sys/malloc.h> 52240116Smarcel#include <sys/mutex.h> 53240116Smarcel#include <sys/proc.h> 54240116Smarcel#include <sys/sdt.h> 55240116Smarcel#include <sys/sleepqueue.h> 56240116Smarcel#include <sys/sysctl.h> 57240116Smarcel#include <sys/smp.h> 58240116Smarcel 59240116SmarcelSDT_PROVIDER_DEFINE(callout_execute); 60240116SmarcelSDT_PROBE_DEFINE(callout_execute, kernel, , callout_start); 61240116SmarcelSDT_PROBE_ARGTYPE(callout_execute, kernel, , callout_start, 0, 62240116Smarcel "struct callout *"); 63240116SmarcelSDT_PROBE_DEFINE(callout_execute, kernel, , callout_end); 64240116SmarcelSDT_PROBE_ARGTYPE(callout_execute, kernel, , callout_end, 0, 65240116Smarcel "struct callout *"); 66240116Smarcel 67240116Smarcelstatic int avg_depth; 68240116SmarcelSYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0, 69275988Sngie "Average number of items examined per softclock call. Units = 1/1000"); 70static int avg_gcalls; 71SYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0, 72 "Average number of Giant callouts made per softclock call. Units = 1/1000"); 73static int avg_lockcalls; 74SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls, CTLFLAG_RD, &avg_lockcalls, 0, 75 "Average number of lock callouts made per softclock call. Units = 1/1000"); 76static int avg_mpcalls; 77SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0, 78 "Average number of MP callouts made per softclock call. Units = 1/1000"); 79/* 80 * TODO: 81 * allocate more timeout table slots when table overflows. 82 */ 83int callwheelsize, callwheelbits, callwheelmask; 84 85/* 86 * There is one struct callout_cpu per cpu, holding all relevant 87 * state for the callout processing thread on the individual CPU. 88 * In particular: 89 * cc_ticks is incremented once per tick in callout_cpu(). 90 * It tracks the global 'ticks' but in a way that the individual 91 * threads should not worry about races in the order in which 92 * hardclock() and hardclock_cpu() run on the various CPUs. 93 * cc_softclock is advanced in callout_cpu() to point to the 94 * first entry in cc_callwheel that may need handling. In turn, 95 * a softclock() is scheduled so it can serve the various entries i 96 * such that cc_softclock <= i <= cc_ticks . 97 * XXX maybe cc_softclock and cc_ticks should be volatile ? 98 * 99 * cc_ticks is also used in callout_reset_cpu() to determine 100 * when the callout should be served. 101 */ 102struct callout_cpu { 103 struct mtx cc_lock; 104 struct callout *cc_callout; 105 struct callout_tailq *cc_callwheel; 106 struct callout_list cc_callfree; 107 struct callout *cc_next; 108 struct callout *cc_curr; 109 void *cc_cookie; 110 int cc_ticks; 111 int cc_softticks; 112 int cc_cancel; 113 int cc_waiting; 114}; 115 116#ifdef SMP 117struct callout_cpu cc_cpu[MAXCPU]; 118#define CC_CPU(cpu) (&cc_cpu[(cpu)]) 119#define CC_SELF() CC_CPU(PCPU_GET(cpuid)) 120#else 121struct callout_cpu cc_cpu; 122#define CC_CPU(cpu) &cc_cpu 123#define CC_SELF() &cc_cpu 124#endif 125#define CC_LOCK(cc) mtx_lock_spin(&(cc)->cc_lock) 126#define CC_UNLOCK(cc) mtx_unlock_spin(&(cc)->cc_lock) 127 128static int timeout_cpu; 129 130MALLOC_DEFINE(M_CALLOUT, "callout", "Callout datastructures"); 131 132/** 133 * Locked by cc_lock: 134 * cc_curr - If a callout is in progress, it is curr_callout. 135 * If curr_callout is non-NULL, threads waiting in 136 * callout_drain() will be woken up as soon as the 137 * relevant callout completes. 138 * cc_cancel - Changing to 1 with both callout_lock and c_lock held 139 * guarantees that the current callout will not run. 140 * The softclock() function sets this to 0 before it 141 * drops callout_lock to acquire c_lock, and it calls 142 * the handler only if curr_cancelled is still 0 after 143 * c_lock is successfully acquired. 144 * cc_waiting - If a thread is waiting in callout_drain(), then 145 * callout_wait is nonzero. Set only when 146 * curr_callout is non-NULL. 147 */ 148 149/* 150 * kern_timeout_callwheel_alloc() - kernel low level callwheel initialization 151 * 152 * This code is called very early in the kernel initialization sequence, 153 * and may be called more then once. 154 */ 155caddr_t 156kern_timeout_callwheel_alloc(caddr_t v) 157{ 158 struct callout_cpu *cc; 159 160 timeout_cpu = PCPU_GET(cpuid); 161 cc = CC_CPU(timeout_cpu); 162 /* 163 * Calculate callout wheel size 164 */ 165 for (callwheelsize = 1, callwheelbits = 0; 166 callwheelsize < ncallout; 167 callwheelsize <<= 1, ++callwheelbits) 168 ; 169 callwheelmask = callwheelsize - 1; 170 171 cc->cc_callout = (struct callout *)v; 172 v = (caddr_t)(cc->cc_callout + ncallout); 173 cc->cc_callwheel = (struct callout_tailq *)v; 174 v = (caddr_t)(cc->cc_callwheel + callwheelsize); 175 return(v); 176} 177 178static void 179callout_cpu_init(struct callout_cpu *cc) 180{ 181 struct callout *c; 182 int i; 183 184 mtx_init(&cc->cc_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE); 185 SLIST_INIT(&cc->cc_callfree); 186 for (i = 0; i < callwheelsize; i++) { 187 TAILQ_INIT(&cc->cc_callwheel[i]); 188 } 189 if (cc->cc_callout == NULL) 190 return; 191 for (i = 0; i < ncallout; i++) { 192 c = &cc->cc_callout[i]; 193 callout_init(c, 0); 194 c->c_flags = CALLOUT_LOCAL_ALLOC; 195 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle); 196 } 197} 198 199/* 200 * kern_timeout_callwheel_init() - initialize previously reserved callwheel 201 * space. 202 * 203 * This code is called just once, after the space reserved for the 204 * callout wheel has been finalized. 205 */ 206void 207kern_timeout_callwheel_init(void) 208{ 209 callout_cpu_init(CC_CPU(timeout_cpu)); 210} 211 212/* 213 * Start standard softclock thread. 214 */ 215void *softclock_ih; 216 217static void 218start_softclock(void *dummy) 219{ 220 struct callout_cpu *cc; 221#ifdef SMP 222 int cpu; 223#endif 224 225 cc = CC_CPU(timeout_cpu); 226 if (swi_add(&clk_intr_event, "clock", softclock, cc, SWI_CLOCK, 227 INTR_MPSAFE, &softclock_ih)) 228 panic("died while creating standard software ithreads"); 229 cc->cc_cookie = softclock_ih; 230#ifdef SMP 231 CPU_FOREACH(cpu) { 232 if (cpu == timeout_cpu) 233 continue; 234 cc = CC_CPU(cpu); 235 if (swi_add(NULL, "clock", softclock, cc, SWI_CLOCK, 236 INTR_MPSAFE, &cc->cc_cookie)) 237 panic("died while creating standard software ithreads"); 238 cc->cc_callout = NULL; /* Only cpu0 handles timeout(). */ 239 cc->cc_callwheel = malloc( 240 sizeof(struct callout_tailq) * callwheelsize, M_CALLOUT, 241 M_WAITOK); 242 callout_cpu_init(cc); 243 } 244#endif 245} 246 247SYSINIT(start_softclock, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_softclock, NULL); 248 249void 250callout_tick(void) 251{ 252 struct callout_cpu *cc; 253 int need_softclock; 254 int bucket; 255 256 /* 257 * Process callouts at a very low cpu priority, so we don't keep the 258 * relatively high clock interrupt priority any longer than necessary. 259 */ 260 need_softclock = 0; 261 cc = CC_SELF(); 262 mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET); 263 cc->cc_ticks++; 264 for (; (cc->cc_softticks - cc->cc_ticks) <= 0; cc->cc_softticks++) { 265 bucket = cc->cc_softticks & callwheelmask; 266 if (!TAILQ_EMPTY(&cc->cc_callwheel[bucket])) { 267 need_softclock = 1; 268 break; 269 } 270 } 271 mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET); 272 /* 273 * swi_sched acquires the thread lock, so we don't want to call it 274 * with cc_lock held; incorrect locking order. 275 */ 276 if (need_softclock) 277 swi_sched(cc->cc_cookie, 0); 278} 279 280static struct callout_cpu * 281callout_lock(struct callout *c) 282{ 283 struct callout_cpu *cc; 284 int cpu; 285 286 for (;;) { 287 cpu = c->c_cpu; 288 cc = CC_CPU(cpu); 289 CC_LOCK(cc); 290 if (cpu == c->c_cpu) 291 break; 292 CC_UNLOCK(cc); 293 } 294 return (cc); 295} 296 297/* 298 * The callout mechanism is based on the work of Adam M. Costello and 299 * George Varghese, published in a technical report entitled "Redesigning 300 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 301 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 302 * used in this implementation was published by G. Varghese and T. Lauck in 303 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 304 * the Efficient Implementation of a Timer Facility" in the Proceedings of 305 * the 11th ACM Annual Symposium on Operating Systems Principles, 306 * Austin, Texas Nov 1987. 307 */ 308 309/* 310 * Software (low priority) clock interrupt. 311 * Run periodic events from timeout queue. 312 */ 313void 314softclock(void *arg) 315{ 316 struct callout_cpu *cc; 317 struct callout *c; 318 struct callout_tailq *bucket; 319 int curticks; 320 int steps; /* #steps since we last allowed interrupts */ 321 int depth; 322 int mpcalls; 323 int lockcalls; 324 int gcalls; 325#ifdef DIAGNOSTIC 326 struct bintime bt1, bt2; 327 struct timespec ts2; 328 static uint64_t maxdt = 36893488147419102LL; /* 2 msec */ 329 static timeout_t *lastfunc; 330#endif 331 332#ifndef MAX_SOFTCLOCK_STEPS 333#define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 334#endif /* MAX_SOFTCLOCK_STEPS */ 335 336 mpcalls = 0; 337 lockcalls = 0; 338 gcalls = 0; 339 depth = 0; 340 steps = 0; 341 cc = (struct callout_cpu *)arg; 342 CC_LOCK(cc); 343 while (cc->cc_softticks - 1 != cc->cc_ticks) { 344 /* 345 * cc_softticks may be modified by hard clock, so cache 346 * it while we work on a given bucket. 347 */ 348 curticks = cc->cc_softticks; 349 cc->cc_softticks++; 350 bucket = &cc->cc_callwheel[curticks & callwheelmask]; 351 c = TAILQ_FIRST(bucket); 352 while (c) { 353 depth++; 354 if (c->c_time != curticks) { 355 c = TAILQ_NEXT(c, c_links.tqe); 356 ++steps; 357 if (steps >= MAX_SOFTCLOCK_STEPS) { 358 cc->cc_next = c; 359 /* Give interrupts a chance. */ 360 CC_UNLOCK(cc); 361 ; /* nothing */ 362 CC_LOCK(cc); 363 c = cc->cc_next; 364 steps = 0; 365 } 366 } else { 367 void (*c_func)(void *); 368 void *c_arg; 369 struct lock_class *class; 370 struct lock_object *c_lock; 371 int c_flags, sharedlock; 372 373 cc->cc_next = TAILQ_NEXT(c, c_links.tqe); 374 TAILQ_REMOVE(bucket, c, c_links.tqe); 375 class = (c->c_lock != NULL) ? 376 LOCK_CLASS(c->c_lock) : NULL; 377 sharedlock = (c->c_flags & CALLOUT_SHAREDLOCK) ? 378 0 : 1; 379 c_lock = c->c_lock; 380 c_func = c->c_func; 381 c_arg = c->c_arg; 382 c_flags = c->c_flags; 383 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 384 c->c_flags = CALLOUT_LOCAL_ALLOC; 385 } else { 386 c->c_flags = 387 (c->c_flags & ~CALLOUT_PENDING); 388 } 389 cc->cc_curr = c; 390 cc->cc_cancel = 0; 391 CC_UNLOCK(cc); 392 if (c_lock != NULL) { 393 class->lc_lock(c_lock, sharedlock); 394 /* 395 * The callout may have been cancelled 396 * while we switched locks. 397 */ 398 if (cc->cc_cancel) { 399 class->lc_unlock(c_lock); 400 goto skip; 401 } 402 /* The callout cannot be stopped now. */ 403 cc->cc_cancel = 1; 404 405 if (c_lock == &Giant.lock_object) { 406 gcalls++; 407 CTR3(KTR_CALLOUT, 408 "callout %p func %p arg %p", 409 c, c_func, c_arg); 410 } else { 411 lockcalls++; 412 CTR3(KTR_CALLOUT, "callout lock" 413 " %p func %p arg %p", 414 c, c_func, c_arg); 415 } 416 } else { 417 mpcalls++; 418 CTR3(KTR_CALLOUT, 419 "callout mpsafe %p func %p arg %p", 420 c, c_func, c_arg); 421 } 422#ifdef DIAGNOSTIC 423 binuptime(&bt1); 424#endif 425 THREAD_NO_SLEEPING(); 426 SDT_PROBE(callout_execute, kernel, , 427 callout_start, c, 0, 0, 0, 0); 428 c_func(c_arg); 429 SDT_PROBE(callout_execute, kernel, , 430 callout_end, c, 0, 0, 0, 0); 431 THREAD_SLEEPING_OK(); 432#ifdef DIAGNOSTIC 433 binuptime(&bt2); 434 bintime_sub(&bt2, &bt1); 435 if (bt2.frac > maxdt) { 436 if (lastfunc != c_func || 437 bt2.frac > maxdt * 2) { 438 bintime2timespec(&bt2, &ts2); 439 printf( 440 "Expensive timeout(9) function: %p(%p) %jd.%09ld s\n", 441 c_func, c_arg, 442 (intmax_t)ts2.tv_sec, 443 ts2.tv_nsec); 444 } 445 maxdt = bt2.frac; 446 lastfunc = c_func; 447 } 448#endif 449 CTR1(KTR_CALLOUT, "callout %p finished", c); 450 if ((c_flags & CALLOUT_RETURNUNLOCKED) == 0) 451 class->lc_unlock(c_lock); 452 skip: 453 CC_LOCK(cc); 454 /* 455 * If the current callout is locally 456 * allocated (from timeout(9)) 457 * then put it on the freelist. 458 * 459 * Note: we need to check the cached 460 * copy of c_flags because if it was not 461 * local, then it's not safe to deref the 462 * callout pointer. 463 */ 464 if (c_flags & CALLOUT_LOCAL_ALLOC) { 465 KASSERT(c->c_flags == 466 CALLOUT_LOCAL_ALLOC, 467 ("corrupted callout")); 468 c->c_func = NULL; 469 SLIST_INSERT_HEAD(&cc->cc_callfree, c, 470 c_links.sle); 471 } 472 cc->cc_curr = NULL; 473 if (cc->cc_waiting) { 474 /* 475 * There is someone waiting 476 * for the callout to complete. 477 */ 478 cc->cc_waiting = 0; 479 CC_UNLOCK(cc); 480 wakeup(&cc->cc_waiting); 481 CC_LOCK(cc); 482 } 483 steps = 0; 484 c = cc->cc_next; 485 } 486 } 487 } 488 avg_depth += (depth * 1000 - avg_depth) >> 8; 489 avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8; 490 avg_lockcalls += (lockcalls * 1000 - avg_lockcalls) >> 8; 491 avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8; 492 cc->cc_next = NULL; 493 CC_UNLOCK(cc); 494} 495 496/* 497 * timeout -- 498 * Execute a function after a specified length of time. 499 * 500 * untimeout -- 501 * Cancel previous timeout function call. 502 * 503 * callout_handle_init -- 504 * Initialize a handle so that using it with untimeout is benign. 505 * 506 * See AT&T BCI Driver Reference Manual for specification. This 507 * implementation differs from that one in that although an 508 * identification value is returned from timeout, the original 509 * arguments to timeout as well as the identifier are used to 510 * identify entries for untimeout. 511 */ 512struct callout_handle 513timeout(ftn, arg, to_ticks) 514 timeout_t *ftn; 515 void *arg; 516 int to_ticks; 517{ 518 struct callout_cpu *cc; 519 struct callout *new; 520 struct callout_handle handle; 521 522 cc = CC_CPU(timeout_cpu); 523 CC_LOCK(cc); 524 /* Fill in the next free callout structure. */ 525 new = SLIST_FIRST(&cc->cc_callfree); 526 if (new == NULL) 527 /* XXX Attempt to malloc first */ 528 panic("timeout table full"); 529 SLIST_REMOVE_HEAD(&cc->cc_callfree, c_links.sle); 530 callout_reset(new, to_ticks, ftn, arg); 531 handle.callout = new; 532 CC_UNLOCK(cc); 533 534 return (handle); 535} 536 537void 538untimeout(ftn, arg, handle) 539 timeout_t *ftn; 540 void *arg; 541 struct callout_handle handle; 542{ 543 struct callout_cpu *cc; 544 545 /* 546 * Check for a handle that was initialized 547 * by callout_handle_init, but never used 548 * for a real timeout. 549 */ 550 if (handle.callout == NULL) 551 return; 552 553 cc = callout_lock(handle.callout); 554 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 555 callout_stop(handle.callout); 556 CC_UNLOCK(cc); 557} 558 559void 560callout_handle_init(struct callout_handle *handle) 561{ 562 handle->callout = NULL; 563} 564 565/* 566 * New interface; clients allocate their own callout structures. 567 * 568 * callout_reset() - establish or change a timeout 569 * callout_stop() - disestablish a timeout 570 * callout_init() - initialize a callout structure so that it can 571 * safely be passed to callout_reset() and callout_stop() 572 * 573 * <sys/callout.h> defines three convenience macros: 574 * 575 * callout_active() - returns truth if callout has not been stopped, 576 * drained, or deactivated since the last time the callout was 577 * reset. 578 * callout_pending() - returns truth if callout is still waiting for timeout 579 * callout_deactivate() - marks the callout as having been serviced 580 */ 581int 582callout_reset_on(struct callout *c, int to_ticks, void (*ftn)(void *), 583 void *arg, int cpu) 584{ 585 struct callout_cpu *cc; 586 int cancelled = 0; 587 588 /* 589 * Don't allow migration of pre-allocated callouts lest they 590 * become unbalanced. 591 */ 592 if (c->c_flags & CALLOUT_LOCAL_ALLOC) 593 cpu = c->c_cpu; 594retry: 595 cc = callout_lock(c); 596 if (cc->cc_curr == c) { 597 /* 598 * We're being asked to reschedule a callout which is 599 * currently in progress. If there is a lock then we 600 * can cancel the callout if it has not really started. 601 */ 602 if (c->c_lock != NULL && !cc->cc_cancel) 603 cancelled = cc->cc_cancel = 1; 604 if (cc->cc_waiting) { 605 /* 606 * Someone has called callout_drain to kill this 607 * callout. Don't reschedule. 608 */ 609 CTR4(KTR_CALLOUT, "%s %p func %p arg %p", 610 cancelled ? "cancelled" : "failed to cancel", 611 c, c->c_func, c->c_arg); 612 CC_UNLOCK(cc); 613 return (cancelled); 614 } 615 } 616 if (c->c_flags & CALLOUT_PENDING) { 617 if (cc->cc_next == c) { 618 cc->cc_next = TAILQ_NEXT(c, c_links.tqe); 619 } 620 TAILQ_REMOVE(&cc->cc_callwheel[c->c_time & callwheelmask], c, 621 c_links.tqe); 622 623 cancelled = 1; 624 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 625 } 626 /* 627 * If the lock must migrate we have to check the state again as 628 * we can't hold both the new and old locks simultaneously. 629 */ 630 if (c->c_cpu != cpu) { 631 c->c_cpu = cpu; 632 CC_UNLOCK(cc); 633 goto retry; 634 } 635 636 if (to_ticks <= 0) 637 to_ticks = 1; 638 639 c->c_arg = arg; 640 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING); 641 c->c_func = ftn; 642 c->c_time = cc->cc_ticks + to_ticks; 643 TAILQ_INSERT_TAIL(&cc->cc_callwheel[c->c_time & callwheelmask], 644 c, c_links.tqe); 645 CTR5(KTR_CALLOUT, "%sscheduled %p func %p arg %p in %d", 646 cancelled ? "re" : "", c, c->c_func, c->c_arg, to_ticks); 647 CC_UNLOCK(cc); 648 649 return (cancelled); 650} 651 652/* 653 * Common idioms that can be optimized in the future. 654 */ 655int 656callout_schedule_on(struct callout *c, int to_ticks, int cpu) 657{ 658 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, cpu); 659} 660 661int 662callout_schedule(struct callout *c, int to_ticks) 663{ 664 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, c->c_cpu); 665} 666 667int 668_callout_stop_safe(c, safe) 669 struct callout *c; 670 int safe; 671{ 672 struct callout_cpu *cc; 673 struct lock_class *class; 674 int use_lock, sq_locked; 675 676 /* 677 * Some old subsystems don't hold Giant while running a callout_stop(), 678 * so just discard this check for the moment. 679 */ 680 if (!safe && c->c_lock != NULL) { 681 if (c->c_lock == &Giant.lock_object) 682 use_lock = mtx_owned(&Giant); 683 else { 684 use_lock = 1; 685 class = LOCK_CLASS(c->c_lock); 686 class->lc_assert(c->c_lock, LA_XLOCKED); 687 } 688 } else 689 use_lock = 0; 690 691 sq_locked = 0; 692again: 693 cc = callout_lock(c); 694 /* 695 * If the callout isn't pending, it's not on the queue, so 696 * don't attempt to remove it from the queue. We can try to 697 * stop it by other means however. 698 */ 699 if (!(c->c_flags & CALLOUT_PENDING)) { 700 c->c_flags &= ~CALLOUT_ACTIVE; 701 702 /* 703 * If it wasn't on the queue and it isn't the current 704 * callout, then we can't stop it, so just bail. 705 */ 706 if (cc->cc_curr != c) { 707 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 708 c, c->c_func, c->c_arg); 709 CC_UNLOCK(cc); 710 if (sq_locked) 711 sleepq_release(&cc->cc_waiting); 712 return (0); 713 } 714 715 if (safe) { 716 /* 717 * The current callout is running (or just 718 * about to run) and blocking is allowed, so 719 * just wait for the current invocation to 720 * finish. 721 */ 722 while (cc->cc_curr == c) { 723 724 /* 725 * Use direct calls to sleepqueue interface 726 * instead of cv/msleep in order to avoid 727 * a LOR between cc_lock and sleepqueue 728 * chain spinlocks. This piece of code 729 * emulates a msleep_spin() call actually. 730 * 731 * If we already have the sleepqueue chain 732 * locked, then we can safely block. If we 733 * don't already have it locked, however, 734 * we have to drop the cc_lock to lock 735 * it. This opens several races, so we 736 * restart at the beginning once we have 737 * both locks. If nothing has changed, then 738 * we will end up back here with sq_locked 739 * set. 740 */ 741 if (!sq_locked) { 742 CC_UNLOCK(cc); 743 sleepq_lock(&cc->cc_waiting); 744 sq_locked = 1; 745 goto again; 746 } 747 cc->cc_waiting = 1; 748 DROP_GIANT(); 749 CC_UNLOCK(cc); 750 sleepq_add(&cc->cc_waiting, 751 &cc->cc_lock.lock_object, "codrain", 752 SLEEPQ_SLEEP, 0); 753 sleepq_wait(&cc->cc_waiting, 0); 754 sq_locked = 0; 755 756 /* Reacquire locks previously released. */ 757 PICKUP_GIANT(); 758 CC_LOCK(cc); 759 } 760 } else if (use_lock && !cc->cc_cancel) { 761 /* 762 * The current callout is waiting for its 763 * lock which we hold. Cancel the callout 764 * and return. After our caller drops the 765 * lock, the callout will be skipped in 766 * softclock(). 767 */ 768 cc->cc_cancel = 1; 769 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 770 c, c->c_func, c->c_arg); 771 CC_UNLOCK(cc); 772 KASSERT(!sq_locked, ("sleepqueue chain locked")); 773 return (1); 774 } 775 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 776 c, c->c_func, c->c_arg); 777 CC_UNLOCK(cc); 778 KASSERT(!sq_locked, ("sleepqueue chain still locked")); 779 return (0); 780 } 781 if (sq_locked) 782 sleepq_release(&cc->cc_waiting); 783 784 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 785 786 if (cc->cc_next == c) { 787 cc->cc_next = TAILQ_NEXT(c, c_links.tqe); 788 } 789 TAILQ_REMOVE(&cc->cc_callwheel[c->c_time & callwheelmask], c, 790 c_links.tqe); 791 792 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 793 c, c->c_func, c->c_arg); 794 795 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 796 c->c_func = NULL; 797 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle); 798 } 799 CC_UNLOCK(cc); 800 return (1); 801} 802 803void 804callout_init(c, mpsafe) 805 struct callout *c; 806 int mpsafe; 807{ 808 bzero(c, sizeof *c); 809 if (mpsafe) { 810 c->c_lock = NULL; 811 c->c_flags = CALLOUT_RETURNUNLOCKED; 812 } else { 813 c->c_lock = &Giant.lock_object; 814 c->c_flags = 0; 815 } 816 c->c_cpu = timeout_cpu; 817} 818 819void 820_callout_init_lock(c, lock, flags) 821 struct callout *c; 822 struct lock_object *lock; 823 int flags; 824{ 825 bzero(c, sizeof *c); 826 c->c_lock = lock; 827 KASSERT((flags & ~(CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK)) == 0, 828 ("callout_init_lock: bad flags %d", flags)); 829 KASSERT(lock != NULL || (flags & CALLOUT_RETURNUNLOCKED) == 0, 830 ("callout_init_lock: CALLOUT_RETURNUNLOCKED with no lock")); 831 KASSERT(lock == NULL || !(LOCK_CLASS(lock)->lc_flags & 832 (LC_SPINLOCK | LC_SLEEPABLE)), ("%s: invalid lock class", 833 __func__)); 834 c->c_flags = flags & (CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK); 835 c->c_cpu = timeout_cpu; 836} 837 838#ifdef APM_FIXUP_CALLTODO 839/* 840 * Adjust the kernel calltodo timeout list. This routine is used after 841 * an APM resume to recalculate the calltodo timer list values with the 842 * number of hz's we have been sleeping. The next hardclock() will detect 843 * that there are fired timers and run softclock() to execute them. 844 * 845 * Please note, I have not done an exhaustive analysis of what code this 846 * might break. I am motivated to have my select()'s and alarm()'s that 847 * have expired during suspend firing upon resume so that the applications 848 * which set the timer can do the maintanence the timer was for as close 849 * as possible to the originally intended time. Testing this code for a 850 * week showed that resuming from a suspend resulted in 22 to 25 timers 851 * firing, which seemed independant on whether the suspend was 2 hours or 852 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 853 */ 854void 855adjust_timeout_calltodo(time_change) 856 struct timeval *time_change; 857{ 858 register struct callout *p; 859 unsigned long delta_ticks; 860 861 /* 862 * How many ticks were we asleep? 863 * (stolen from tvtohz()). 864 */ 865 866 /* Don't do anything */ 867 if (time_change->tv_sec < 0) 868 return; 869 else if (time_change->tv_sec <= LONG_MAX / 1000000) 870 delta_ticks = (time_change->tv_sec * 1000000 + 871 time_change->tv_usec + (tick - 1)) / tick + 1; 872 else if (time_change->tv_sec <= LONG_MAX / hz) 873 delta_ticks = time_change->tv_sec * hz + 874 (time_change->tv_usec + (tick - 1)) / tick + 1; 875 else 876 delta_ticks = LONG_MAX; 877 878 if (delta_ticks > INT_MAX) 879 delta_ticks = INT_MAX; 880 881 /* 882 * Now rip through the timer calltodo list looking for timers 883 * to expire. 884 */ 885 886 /* don't collide with softclock() */ 887 CC_LOCK(cc); 888 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 889 p->c_time -= delta_ticks; 890 891 /* Break if the timer had more time on it than delta_ticks */ 892 if (p->c_time > 0) 893 break; 894 895 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 896 delta_ticks = -p->c_time; 897 } 898 CC_UNLOCK(cc); 899 900 return; 901} 902#endif /* APM_FIXUP_CALLTODO */ 903