kern_timeout.c revision 184385
1327952Sdim/*- 2226586Sdim * Copyright (c) 1982, 1986, 1991, 1993 3353358Sdim * The Regents of the University of California. All rights reserved. 4353358Sdim * (c) UNIX System Laboratories, Inc. 5353358Sdim * All or some portions of this file are derived from material licensed 6226586Sdim * to the University of California by American Telephone and Telegraph 7226586Sdim * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8226586Sdim * the permission of UNIX System Laboratories, Inc. 9341825Sdim * 10226586Sdim * Redistribution and use in source and binary forms, with or without 11226586Sdim * modification, are permitted provided that the following conditions 12226586Sdim * are met: 13327952Sdim * 1. Redistributions of source code must retain the above copyright 14280031Sdim * notice, this list of conditions and the following disclaimer. 15280031Sdim * 2. Redistributions in binary form must reproduce the above copyright 16226586Sdim * notice, this list of conditions and the following disclaimer in the 17327952Sdim * documentation and/or other materials provided with the distribution. 18234353Sdim * 4. Neither the name of the University nor the names of its contributors 19226586Sdim * may be used to endorse or promote products derived from this software 20234353Sdim * without specific prior written permission. 21249423Sdim * 22327952Sdim * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23327952Sdim * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24226586Sdim * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25226586Sdim * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26226586Sdim * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27276479Sdim * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28226586Sdim * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29249423Sdim * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30341825Sdim * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31234353Sdim * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32327952Sdim * SUCH DAMAGE. 33249423Sdim * 34341825Sdim * From: @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 35249423Sdim */ 36314564Sdim 37314564Sdim#include <sys/cdefs.h> 38314564Sdim__FBSDID("$FreeBSD: head/sys/kern/kern_timeout.c 184385 2008-10-28 03:26:25Z peter $"); 39314564Sdim 40327952Sdim#include <sys/param.h> 41314564Sdim#include <sys/systm.h> 42314564Sdim#include <sys/bus.h> 43314564Sdim#include <sys/callout.h> 44314564Sdim#include <sys/condvar.h> 45327952Sdim#include <sys/interrupt.h> 46314564Sdim#include <sys/kernel.h> 47360784Sdim#include <sys/ktr.h> 48360784Sdim#include <sys/lock.h> 49360784Sdim#include <sys/malloc.h> 50360784Sdim#include <sys/mutex.h> 51314564Sdim#include <sys/proc.h> 52314564Sdim#include <sys/sleepqueue.h> 53249423Sdim#include <sys/sysctl.h> 54327952Sdim#include <sys/smp.h> 55314564Sdim 56314564Sdimstatic int avg_depth; 57249423SdimSYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0, 58249423Sdim "Average number of items examined per softclock call. Units = 1/1000"); 59249423Sdimstatic int avg_gcalls; 60360784SdimSYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0, 61360784Sdim "Average number of Giant callouts made per softclock call. Units = 1/1000"); 62360784Sdimstatic int avg_lockcalls; 63360784SdimSYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls, CTLFLAG_RD, &avg_lockcalls, 0, 64341825Sdim "Average number of lock callouts made per softclock call. Units = 1/1000"); 65249423Sdimstatic int avg_mpcalls; 66249423SdimSYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0, 67249423Sdim "Average number of MP callouts made per softclock call. Units = 1/1000"); 68314564Sdim/* 69314564Sdim * TODO: 70341825Sdim * allocate more timeout table slots when table overflows. 71314564Sdim */ 72314564Sdimint callwheelsize, callwheelbits, callwheelmask; 73249423Sdim 74249423Sdimstruct callout_cpu { 75341825Sdim struct mtx cc_lock; 76226586Sdim struct callout *cc_callout; 77226586Sdim struct callout_tailq *cc_callwheel; 78226586Sdim struct callout_list cc_callfree; 79226586Sdim struct callout *cc_next; 80226586Sdim struct callout *cc_curr; 81276479Sdim void *cc_cookie; 82276479Sdim int cc_softticks; 83327952Sdim int cc_cancel; 84226586Sdim int cc_waiting; 85327952Sdim}; 86327952Sdim 87261991Sdim#ifdef SMP 88226586Sdimstruct callout_cpu cc_cpu[MAXCPU]; 89341825Sdim#define CC_CPU(cpu) (&cc_cpu[(cpu)]) 90341825Sdim#define CC_SELF() CC_CPU(PCPU_GET(cpuid)) 91276479Sdim#else 92276479Sdimstruct callout_cpu cc_cpu; 93276479Sdim#define CC_CPU(cpu) &cc_cpu 94327952Sdim#define CC_SELF() &cc_cpu 95341825Sdim#endif 96276479Sdim#define CC_LOCK(cc) mtx_lock_spin(&(cc)->cc_lock) 97276479Sdim#define CC_UNLOCK(cc) mtx_unlock_spin(&(cc)->cc_lock) 98276479Sdim 99341825Sdimstatic int timeout_cpu; 100341825Sdim 101226586SdimMALLOC_DEFINE(M_CALLOUT, "callout", "Callout datastructures"); 102341825Sdim 103360784Sdim/** 104360784Sdim * Locked by cc_lock: 105226586Sdim * cc_curr - If a callout is in progress, it is curr_callout. 106226586Sdim * If curr_callout is non-NULL, threads waiting in 107226586Sdim * callout_drain() will be woken up as soon as the 108234353Sdim * relevant callout completes. 109234353Sdim * cc_cancel - Changing to 1 with both callout_lock and c_lock held 110341825Sdim * guarantees that the current callout will not run. 111234353Sdim * The softclock() function sets this to 0 before it 112234353Sdim * drops callout_lock to acquire c_lock, and it calls 113234353Sdim * the handler only if curr_cancelled is still 0 after 114234353Sdim * c_lock is successfully acquired. 115234353Sdim * cc_waiting - If a thread is waiting in callout_drain(), then 116234353Sdim * callout_wait is nonzero. Set only when 117234353Sdim * curr_callout is non-NULL. 118341825Sdim */ 119234353Sdim 120249423Sdim/* 121249423Sdim * kern_timeout_callwheel_alloc() - kernel low level callwheel initialization 122249423Sdim * 123249423Sdim * This code is called very early in the kernel initialization sequence, 124249423Sdim * and may be called more then once. 125360784Sdim */ 126360784Sdimcaddr_t 127360784Sdimkern_timeout_callwheel_alloc(caddr_t v) 128321369Sdim{ 129360784Sdim struct callout_cpu *cc; 130360784Sdim 131321369Sdim timeout_cpu = PCPU_GET(cpuid); 132360784Sdim cc = CC_CPU(timeout_cpu); 133360784Sdim /* 134321369Sdim * Calculate callout wheel size 135341825Sdim */ 136249423Sdim for (callwheelsize = 1, callwheelbits = 0; 137249423Sdim callwheelsize < ncallout; 138288943Sdim callwheelsize <<= 1, ++callwheelbits) 139261991Sdim ; 140341825Sdim callwheelmask = callwheelsize - 1; 141276479Sdim 142276479Sdim cc->cc_callout = (struct callout *)v; 143276479Sdim v = (caddr_t)(cc->cc_callout + ncallout); 144276479Sdim cc->cc_callwheel = (struct callout_tailq *)v; 145276479Sdim v = (caddr_t)(cc->cc_callwheel + callwheelsize); 146276479Sdim return(v); 147276479Sdim} 148276479Sdim 149276479Sdimstatic void 150276479Sdimcallout_cpu_init(struct callout_cpu *cc) 151276479Sdim{ 152276479Sdim struct callout *c; 153276479Sdim int i; 154276479Sdim 155276479Sdim mtx_init(&cc->cc_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE); 156276479Sdim SLIST_INIT(&cc->cc_callfree); 157276479Sdim for (i = 0; i < callwheelsize; i++) { 158276479Sdim TAILQ_INIT(&cc->cc_callwheel[i]); 159276479Sdim } 160327952Sdim if (cc->cc_callout == NULL) 161226586Sdim return; 162321369Sdim for (i = 0; i < ncallout; i++) { 163360784Sdim c = &cc->cc_callout[i]; 164321369Sdim callout_init(c, 0); 165321369Sdim c->c_flags = CALLOUT_LOCAL_ALLOC; 166321369Sdim SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle); 167321369Sdim } 168321369Sdim} 169327952Sdim 170321369Sdim/* 171321369Sdim * kern_timeout_callwheel_init() - initialize previously reserved callwheel 172360784Sdim * space. 173360784Sdim * 174321369Sdim * This code is called just once, after the space reserved for the 175321369Sdim * callout wheel has been finalized. 176321369Sdim */ 177321369Sdimvoid 178321369Sdimkern_timeout_callwheel_init(void) 179321369Sdim{ 180321369Sdim callout_cpu_init(CC_CPU(timeout_cpu)); 181327952Sdim} 182321369Sdim 183321369Sdim/* 184327952Sdim * Start standard softclock thread. 185321369Sdim */ 186321369Sdimvoid *softclock_ih; 187341825Sdim 188327952Sdimstatic void 189226586Sdimstart_softclock(void *dummy) 190327952Sdim{ 191 struct callout_cpu *cc; 192#ifdef SMP 193 int cpu; 194#endif 195 196 cc = CC_CPU(timeout_cpu); 197 if (swi_add(&clk_intr_event, "clock", softclock, cc, SWI_CLOCK, 198 INTR_MPSAFE, &softclock_ih)) 199 panic("died while creating standard software ithreads"); 200 cc->cc_cookie = softclock_ih; 201#ifdef SMP 202 for (cpu = 0; cpu <= mp_maxid; cpu++) { 203 if (cpu == timeout_cpu) 204 continue; 205 if (CPU_ABSENT(cpu)) 206 continue; 207 cc = CC_CPU(cpu); 208 if (swi_add(NULL, "clock", softclock, cc, SWI_CLOCK, 209 INTR_MPSAFE, &cc->cc_cookie)) 210 panic("died while creating standard software ithreads"); 211 cc->cc_callout = NULL; /* Only cpu0 handles timeout(). */ 212 cc->cc_callwheel = malloc( 213 sizeof(struct callout_tailq) * callwheelsize, M_CALLOUT, 214 M_WAITOK); 215 callout_cpu_init(cc); 216 } 217#endif 218} 219 220SYSINIT(start_softclock, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_softclock, NULL); 221 222void 223callout_tick(void) 224{ 225 struct callout_cpu *cc; 226 int need_softclock; 227 int bucket; 228 229 /* 230 * Process callouts at a very low cpu priority, so we don't keep the 231 * relatively high clock interrupt priority any longer than necessary. 232 */ 233 need_softclock = 0; 234 cc = CC_SELF(); 235 mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET); 236 for (; (cc->cc_softticks - ticks) < 0; cc->cc_softticks++) { 237 bucket = cc->cc_softticks & callwheelmask; 238 if (!TAILQ_EMPTY(&cc->cc_callwheel[bucket])) { 239 need_softclock = 1; 240 break; 241 } 242 } 243 mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET); 244 /* 245 * swi_sched acquires the thread lock, so we don't want to call it 246 * with cc_lock held; incorrect locking order. 247 */ 248 if (need_softclock) 249 swi_sched(cc->cc_cookie, 0); 250} 251 252static struct callout_cpu * 253callout_lock(struct callout *c) 254{ 255 struct callout_cpu *cc; 256 int cpu; 257 258 for (;;) { 259 cpu = c->c_cpu; 260 cc = CC_CPU(cpu); 261 CC_LOCK(cc); 262 if (cpu == c->c_cpu) 263 break; 264 CC_UNLOCK(cc); 265 } 266 return (cc); 267} 268 269/* 270 * The callout mechanism is based on the work of Adam M. Costello and 271 * George Varghese, published in a technical report entitled "Redesigning 272 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 273 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 274 * used in this implementation was published by G. Varghese and T. Lauck in 275 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 276 * the Efficient Implementation of a Timer Facility" in the Proceedings of 277 * the 11th ACM Annual Symposium on Operating Systems Principles, 278 * Austin, Texas Nov 1987. 279 */ 280 281/* 282 * Software (low priority) clock interrupt. 283 * Run periodic events from timeout queue. 284 */ 285void 286softclock(void *arg) 287{ 288 struct callout_cpu *cc; 289 struct callout *c; 290 struct callout_tailq *bucket; 291 int curticks; 292 int steps; /* #steps since we last allowed interrupts */ 293 int depth; 294 int mpcalls; 295 int lockcalls; 296 int gcalls; 297#ifdef DIAGNOSTIC 298 struct bintime bt1, bt2; 299 struct timespec ts2; 300 static uint64_t maxdt = 36893488147419102LL; /* 2 msec */ 301 static timeout_t *lastfunc; 302#endif 303 304#ifndef MAX_SOFTCLOCK_STEPS 305#define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 306#endif /* MAX_SOFTCLOCK_STEPS */ 307 308 mpcalls = 0; 309 lockcalls = 0; 310 gcalls = 0; 311 depth = 0; 312 steps = 0; 313 cc = (struct callout_cpu *)arg; 314 CC_LOCK(cc); 315 while (cc->cc_softticks != ticks) { 316 /* 317 * cc_softticks may be modified by hard clock, so cache 318 * it while we work on a given bucket. 319 */ 320 curticks = cc->cc_softticks; 321 cc->cc_softticks++; 322 bucket = &cc->cc_callwheel[curticks & callwheelmask]; 323 c = TAILQ_FIRST(bucket); 324 while (c) { 325 depth++; 326 if (c->c_time != curticks) { 327 c = TAILQ_NEXT(c, c_links.tqe); 328 ++steps; 329 if (steps >= MAX_SOFTCLOCK_STEPS) { 330 cc->cc_next = c; 331 /* Give interrupts a chance. */ 332 CC_UNLOCK(cc); 333 ; /* nothing */ 334 CC_LOCK(cc); 335 c = cc->cc_next; 336 steps = 0; 337 } 338 } else { 339 void (*c_func)(void *); 340 void *c_arg; 341 struct lock_class *class; 342 struct lock_object *c_lock; 343 int c_flags, sharedlock; 344 345 cc->cc_next = TAILQ_NEXT(c, c_links.tqe); 346 TAILQ_REMOVE(bucket, c, c_links.tqe); 347 class = (c->c_lock != NULL) ? 348 LOCK_CLASS(c->c_lock) : NULL; 349 sharedlock = (c->c_flags & CALLOUT_SHAREDLOCK) ? 350 0 : 1; 351 c_lock = c->c_lock; 352 c_func = c->c_func; 353 c_arg = c->c_arg; 354 c_flags = c->c_flags; 355 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 356 c->c_flags = CALLOUT_LOCAL_ALLOC; 357 } else { 358 c->c_flags = 359 (c->c_flags & ~CALLOUT_PENDING); 360 } 361 cc->cc_curr = c; 362 cc->cc_cancel = 0; 363 CC_UNLOCK(cc); 364 if (c_lock != NULL) { 365 class->lc_lock(c_lock, sharedlock); 366 /* 367 * The callout may have been cancelled 368 * while we switched locks. 369 */ 370 if (cc->cc_cancel) { 371 class->lc_unlock(c_lock); 372 goto skip; 373 } 374 /* The callout cannot be stopped now. */ 375 cc->cc_cancel = 1; 376 377 if (c_lock == &Giant.lock_object) { 378 gcalls++; 379 CTR3(KTR_CALLOUT, 380 "callout %p func %p arg %p", 381 c, c_func, c_arg); 382 } else { 383 lockcalls++; 384 CTR3(KTR_CALLOUT, "callout lock" 385 " %p func %p arg %p", 386 c, c_func, c_arg); 387 } 388 } else { 389 mpcalls++; 390 CTR3(KTR_CALLOUT, 391 "callout mpsafe %p func %p arg %p", 392 c, c_func, c_arg); 393 } 394#ifdef DIAGNOSTIC 395 binuptime(&bt1); 396#endif 397 THREAD_NO_SLEEPING(); 398 c_func(c_arg); 399 THREAD_SLEEPING_OK(); 400#ifdef DIAGNOSTIC 401 binuptime(&bt2); 402 bintime_sub(&bt2, &bt1); 403 if (bt2.frac > maxdt) { 404 if (lastfunc != c_func || 405 bt2.frac > maxdt * 2) { 406 bintime2timespec(&bt2, &ts2); 407 printf( 408 "Expensive timeout(9) function: %p(%p) %jd.%09ld s\n", 409 c_func, c_arg, 410 (intmax_t)ts2.tv_sec, 411 ts2.tv_nsec); 412 } 413 maxdt = bt2.frac; 414 lastfunc = c_func; 415 } 416#endif 417 if ((c_flags & CALLOUT_RETURNUNLOCKED) == 0) 418 class->lc_unlock(c_lock); 419 skip: 420 CC_LOCK(cc); 421 /* 422 * If the current callout is locally 423 * allocated (from timeout(9)) 424 * then put it on the freelist. 425 * 426 * Note: we need to check the cached 427 * copy of c_flags because if it was not 428 * local, then it's not safe to deref the 429 * callout pointer. 430 */ 431 if (c_flags & CALLOUT_LOCAL_ALLOC) { 432 KASSERT(c->c_flags == 433 CALLOUT_LOCAL_ALLOC, 434 ("corrupted callout")); 435 c->c_func = NULL; 436 SLIST_INSERT_HEAD(&cc->cc_callfree, c, 437 c_links.sle); 438 } 439 cc->cc_curr = NULL; 440 if (cc->cc_waiting) { 441 /* 442 * There is someone waiting 443 * for the callout to complete. 444 */ 445 cc->cc_waiting = 0; 446 CC_UNLOCK(cc); 447 wakeup(&cc->cc_waiting); 448 CC_LOCK(cc); 449 } 450 steps = 0; 451 c = cc->cc_next; 452 } 453 } 454 } 455 avg_depth += (depth * 1000 - avg_depth) >> 8; 456 avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8; 457 avg_lockcalls += (lockcalls * 1000 - avg_lockcalls) >> 8; 458 avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8; 459 cc->cc_next = NULL; 460 CC_UNLOCK(cc); 461} 462 463/* 464 * timeout -- 465 * Execute a function after a specified length of time. 466 * 467 * untimeout -- 468 * Cancel previous timeout function call. 469 * 470 * callout_handle_init -- 471 * Initialize a handle so that using it with untimeout is benign. 472 * 473 * See AT&T BCI Driver Reference Manual for specification. This 474 * implementation differs from that one in that although an 475 * identification value is returned from timeout, the original 476 * arguments to timeout as well as the identifier are used to 477 * identify entries for untimeout. 478 */ 479struct callout_handle 480timeout(ftn, arg, to_ticks) 481 timeout_t *ftn; 482 void *arg; 483 int to_ticks; 484{ 485 struct callout_cpu *cc; 486 struct callout *new; 487 struct callout_handle handle; 488 489 cc = CC_CPU(timeout_cpu); 490 CC_LOCK(cc); 491 /* Fill in the next free callout structure. */ 492 new = SLIST_FIRST(&cc->cc_callfree); 493 if (new == NULL) 494 /* XXX Attempt to malloc first */ 495 panic("timeout table full"); 496 SLIST_REMOVE_HEAD(&cc->cc_callfree, c_links.sle); 497 callout_reset(new, to_ticks, ftn, arg); 498 handle.callout = new; 499 CC_UNLOCK(cc); 500 501 return (handle); 502} 503 504void 505untimeout(ftn, arg, handle) 506 timeout_t *ftn; 507 void *arg; 508 struct callout_handle handle; 509{ 510 struct callout_cpu *cc; 511 512 /* 513 * Check for a handle that was initialized 514 * by callout_handle_init, but never used 515 * for a real timeout. 516 */ 517 if (handle.callout == NULL) 518 return; 519 520 cc = callout_lock(handle.callout); 521 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 522 callout_stop(handle.callout); 523 CC_UNLOCK(cc); 524} 525 526void 527callout_handle_init(struct callout_handle *handle) 528{ 529 handle->callout = NULL; 530} 531 532/* 533 * New interface; clients allocate their own callout structures. 534 * 535 * callout_reset() - establish or change a timeout 536 * callout_stop() - disestablish a timeout 537 * callout_init() - initialize a callout structure so that it can 538 * safely be passed to callout_reset() and callout_stop() 539 * 540 * <sys/callout.h> defines three convenience macros: 541 * 542 * callout_active() - returns truth if callout has not been stopped, 543 * drained, or deactivated since the last time the callout was 544 * reset. 545 * callout_pending() - returns truth if callout is still waiting for timeout 546 * callout_deactivate() - marks the callout as having been serviced 547 */ 548int 549callout_reset_on(struct callout *c, int to_ticks, void (*ftn)(void *), 550 void *arg, int cpu) 551{ 552 struct callout_cpu *cc; 553 int cancelled = 0; 554 555 /* 556 * Don't allow migration of pre-allocated callouts lest they 557 * become unbalanced. 558 */ 559 if (c->c_flags & CALLOUT_LOCAL_ALLOC) 560 cpu = c->c_cpu; 561retry: 562 cc = callout_lock(c); 563 if (cc->cc_curr == c) { 564 /* 565 * We're being asked to reschedule a callout which is 566 * currently in progress. If there is a lock then we 567 * can cancel the callout if it has not really started. 568 */ 569 if (c->c_lock != NULL && !cc->cc_cancel) 570 cancelled = cc->cc_cancel = 1; 571 if (cc->cc_waiting) { 572 /* 573 * Someone has called callout_drain to kill this 574 * callout. Don't reschedule. 575 */ 576 CTR4(KTR_CALLOUT, "%s %p func %p arg %p", 577 cancelled ? "cancelled" : "failed to cancel", 578 c, c->c_func, c->c_arg); 579 CC_UNLOCK(cc); 580 return (cancelled); 581 } 582 } 583 if (c->c_flags & CALLOUT_PENDING) { 584 if (cc->cc_next == c) { 585 cc->cc_next = TAILQ_NEXT(c, c_links.tqe); 586 } 587 TAILQ_REMOVE(&cc->cc_callwheel[c->c_time & callwheelmask], c, 588 c_links.tqe); 589 590 cancelled = 1; 591 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 592 } 593 /* 594 * If the lock must migrate we have to check the state again as 595 * we can't hold both the new and old locks simultaneously. 596 */ 597 if (c->c_cpu != cpu) { 598 c->c_cpu = cpu; 599 CC_UNLOCK(cc); 600 goto retry; 601 } 602 603 if (to_ticks <= 0) 604 to_ticks = 1; 605 606 c->c_arg = arg; 607 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING); 608 c->c_func = ftn; 609 c->c_time = ticks + to_ticks; 610 TAILQ_INSERT_TAIL(&cc->cc_callwheel[c->c_time & callwheelmask], 611 c, c_links.tqe); 612 CTR5(KTR_CALLOUT, "%sscheduled %p func %p arg %p in %d", 613 cancelled ? "re" : "", c, c->c_func, c->c_arg, to_ticks); 614 CC_UNLOCK(cc); 615 616 return (cancelled); 617} 618 619/* 620 * Common idioms that can be optimized in the future. 621 */ 622int 623callout_schedule_on(struct callout *c, int to_ticks, int cpu) 624{ 625 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, cpu); 626} 627 628int 629callout_schedule(struct callout *c, int to_ticks) 630{ 631 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, c->c_cpu); 632} 633 634int 635_callout_stop_safe(c, safe) 636 struct callout *c; 637 int safe; 638{ 639 struct callout_cpu *cc; 640 struct lock_class *class; 641 int use_lock, sq_locked; 642 643 /* 644 * Some old subsystems don't hold Giant while running a callout_stop(), 645 * so just discard this check for the moment. 646 */ 647 if (!safe && c->c_lock != NULL) { 648 if (c->c_lock == &Giant.lock_object) 649 use_lock = mtx_owned(&Giant); 650 else { 651 use_lock = 1; 652 class = LOCK_CLASS(c->c_lock); 653 class->lc_assert(c->c_lock, LA_XLOCKED); 654 } 655 } else 656 use_lock = 0; 657 658 sq_locked = 0; 659again: 660 cc = callout_lock(c); 661 /* 662 * If the callout isn't pending, it's not on the queue, so 663 * don't attempt to remove it from the queue. We can try to 664 * stop it by other means however. 665 */ 666 if (!(c->c_flags & CALLOUT_PENDING)) { 667 c->c_flags &= ~CALLOUT_ACTIVE; 668 669 /* 670 * If it wasn't on the queue and it isn't the current 671 * callout, then we can't stop it, so just bail. 672 */ 673 if (cc->cc_curr != c) { 674 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 675 c, c->c_func, c->c_arg); 676 CC_UNLOCK(cc); 677 if (sq_locked) 678 sleepq_release(&cc->cc_waiting); 679 return (0); 680 } 681 682 if (safe) { 683 /* 684 * The current callout is running (or just 685 * about to run) and blocking is allowed, so 686 * just wait for the current invocation to 687 * finish. 688 */ 689 while (cc->cc_curr == c) { 690 691 /* 692 * Use direct calls to sleepqueue interface 693 * instead of cv/msleep in order to avoid 694 * a LOR between cc_lock and sleepqueue 695 * chain spinlocks. This piece of code 696 * emulates a msleep_spin() call actually. 697 * 698 * If we already have the sleepqueue chain 699 * locked, then we can safely block. If we 700 * don't already have it locked, however, 701 * we have to drop the cc_lock to lock 702 * it. This opens several races, so we 703 * restart at the beginning once we have 704 * both locks. If nothing has changed, then 705 * we will end up back here with sq_locked 706 * set. 707 */ 708 if (!sq_locked) { 709 CC_UNLOCK(cc); 710 sleepq_lock(&cc->cc_waiting); 711 sq_locked = 1; 712 goto again; 713 } 714 cc->cc_waiting = 1; 715 DROP_GIANT(); 716 CC_UNLOCK(cc); 717 sleepq_add(&cc->cc_waiting, 718 &cc->cc_lock.lock_object, "codrain", 719 SLEEPQ_SLEEP, 0); 720 sleepq_wait(&cc->cc_waiting, 0); 721 sq_locked = 0; 722 723 /* Reacquire locks previously released. */ 724 PICKUP_GIANT(); 725 CC_LOCK(cc); 726 } 727 } else if (use_lock && !cc->cc_cancel) { 728 /* 729 * The current callout is waiting for its 730 * lock which we hold. Cancel the callout 731 * and return. After our caller drops the 732 * lock, the callout will be skipped in 733 * softclock(). 734 */ 735 cc->cc_cancel = 1; 736 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 737 c, c->c_func, c->c_arg); 738 CC_UNLOCK(cc); 739 KASSERT(!sq_locked, ("sleepqueue chain locked")); 740 return (1); 741 } 742 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 743 c, c->c_func, c->c_arg); 744 CC_UNLOCK(cc); 745 KASSERT(!sq_locked, ("sleepqueue chain still locked")); 746 return (0); 747 } 748 if (sq_locked) 749 sleepq_release(&cc->cc_waiting); 750 751 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 752 753 if (cc->cc_next == c) { 754 cc->cc_next = TAILQ_NEXT(c, c_links.tqe); 755 } 756 TAILQ_REMOVE(&cc->cc_callwheel[c->c_time & callwheelmask], c, 757 c_links.tqe); 758 759 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 760 c, c->c_func, c->c_arg); 761 762 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 763 c->c_func = NULL; 764 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle); 765 } 766 CC_UNLOCK(cc); 767 return (1); 768} 769 770void 771callout_init(c, mpsafe) 772 struct callout *c; 773 int mpsafe; 774{ 775 bzero(c, sizeof *c); 776 if (mpsafe) { 777 c->c_lock = NULL; 778 c->c_flags = CALLOUT_RETURNUNLOCKED; 779 } else { 780 c->c_lock = &Giant.lock_object; 781 c->c_flags = 0; 782 } 783 c->c_cpu = timeout_cpu; 784} 785 786void 787_callout_init_lock(c, lock, flags) 788 struct callout *c; 789 struct lock_object *lock; 790 int flags; 791{ 792 bzero(c, sizeof *c); 793 c->c_lock = lock; 794 KASSERT((flags & ~(CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK)) == 0, 795 ("callout_init_lock: bad flags %d", flags)); 796 KASSERT(lock != NULL || (flags & CALLOUT_RETURNUNLOCKED) == 0, 797 ("callout_init_lock: CALLOUT_RETURNUNLOCKED with no lock")); 798 KASSERT(lock == NULL || !(LOCK_CLASS(lock)->lc_flags & 799 (LC_SPINLOCK | LC_SLEEPABLE)), ("%s: invalid lock class", 800 __func__)); 801 c->c_flags = flags & (CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK); 802 c->c_cpu = timeout_cpu; 803} 804 805#ifdef APM_FIXUP_CALLTODO 806/* 807 * Adjust the kernel calltodo timeout list. This routine is used after 808 * an APM resume to recalculate the calltodo timer list values with the 809 * number of hz's we have been sleeping. The next hardclock() will detect 810 * that there are fired timers and run softclock() to execute them. 811 * 812 * Please note, I have not done an exhaustive analysis of what code this 813 * might break. I am motivated to have my select()'s and alarm()'s that 814 * have expired during suspend firing upon resume so that the applications 815 * which set the timer can do the maintanence the timer was for as close 816 * as possible to the originally intended time. Testing this code for a 817 * week showed that resuming from a suspend resulted in 22 to 25 timers 818 * firing, which seemed independant on whether the suspend was 2 hours or 819 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 820 */ 821void 822adjust_timeout_calltodo(time_change) 823 struct timeval *time_change; 824{ 825 register struct callout *p; 826 unsigned long delta_ticks; 827 828 /* 829 * How many ticks were we asleep? 830 * (stolen from tvtohz()). 831 */ 832 833 /* Don't do anything */ 834 if (time_change->tv_sec < 0) 835 return; 836 else if (time_change->tv_sec <= LONG_MAX / 1000000) 837 delta_ticks = (time_change->tv_sec * 1000000 + 838 time_change->tv_usec + (tick - 1)) / tick + 1; 839 else if (time_change->tv_sec <= LONG_MAX / hz) 840 delta_ticks = time_change->tv_sec * hz + 841 (time_change->tv_usec + (tick - 1)) / tick + 1; 842 else 843 delta_ticks = LONG_MAX; 844 845 if (delta_ticks > INT_MAX) 846 delta_ticks = INT_MAX; 847 848 /* 849 * Now rip through the timer calltodo list looking for timers 850 * to expire. 851 */ 852 853 /* don't collide with softclock() */ 854 CC_LOCK(cc); 855 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 856 p->c_time -= delta_ticks; 857 858 /* Break if the timer had more time on it than delta_ticks */ 859 if (p->c_time > 0) 860 break; 861 862 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 863 delta_ticks = -p->c_time; 864 } 865 CC_UNLOCK(cc); 866 867 return; 868} 869#endif /* APM_FIXUP_CALLTODO */ 870