Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
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/7.4/sys/kern/kern_timeout.c 187561 2009-01-21 18:54:35Z jhb $"); 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/callout.h> 43 #include <sys/condvar.h> 44 #include <sys/kernel.h> 45 #include <sys/ktr.h> 46 #include <sys/lock.h> 47 #include <sys/mutex.h> 48 #include <sys/proc.h> 49 #include <sys/sleepqueue.h> 50 #include <sys/sysctl.h> 51 52 static int avg_depth; 53 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0, 54 "Average number of items examined per softclock call. Units = 1/1000"); 55 static int avg_gcalls; 56 SYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0, 57 "Average number of Giant callouts made per softclock call. Units = 1/1000"); 58 static int avg_mtxcalls; 59 SYSCTL_INT(_debug, OID_AUTO, to_avg_mtxcalls, CTLFLAG_RD, &avg_mtxcalls, 0, 60 "Average number of mtx callouts made per softclock call. Units = 1/1000"); 61 static int avg_mpcalls; 62 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0, 63 "Average number of MP callouts made per softclock call. Units = 1/1000"); 64 /* 65 * TODO: 66 * allocate more timeout table slots when table overflows. 67 */ 68 69 /* Exported to machdep.c and/or kern_clock.c. */ 70 struct callout *callout; 71 struct callout_list callfree; 72 int callwheelsize, callwheelbits, callwheelmask; 73 struct callout_tailq *callwheel; 74 int softticks; /* Like ticks, but for softclock(). */ 75 struct mtx callout_lock; 76 77 static struct callout *nextsoftcheck; /* Next callout to be checked. */ 78 79 /** 80 * Locked by callout_lock: 81 * curr_callout - If a callout is in progress, it is curr_callout. 82 * If curr_callout is non-NULL, threads waiting in 83 * callout_drain() will be woken up as soon as the 84 * relevant callout completes. 85 * curr_cancelled - Changing to 1 with both callout_lock and c_mtx held 86 * guarantees that the current callout will not run. 87 * The softclock() function sets this to 0 before it 88 * drops callout_lock to acquire c_mtx, and it calls 89 * the handler only if curr_cancelled is still 0 after 90 * c_mtx is successfully acquired. 91 * callout_wait - If a thread is waiting in callout_drain(), then 92 * callout_wait is nonzero. Set only when 93 * curr_callout is non-NULL. 94 */ 95 static struct callout *curr_callout; 96 static int curr_cancelled; 97 static int callout_wait; 98 99 /* 100 * kern_timeout_callwheel_alloc() - kernel low level callwheel initialization 101 * 102 * This code is called very early in the kernel initialization sequence, 103 * and may be called more then once. 104 */ 105 caddr_t 106 kern_timeout_callwheel_alloc(caddr_t v) 107 { 108 /* 109 * Calculate callout wheel size 110 */ 111 for (callwheelsize = 1, callwheelbits = 0; 112 callwheelsize < ncallout; 113 callwheelsize <<= 1, ++callwheelbits) 114 ; 115 callwheelmask = callwheelsize - 1; 116 117 callout = (struct callout *)v; 118 v = (caddr_t)(callout + ncallout); 119 callwheel = (struct callout_tailq *)v; 120 v = (caddr_t)(callwheel + callwheelsize); 121 return(v); 122 } 123 124 /* 125 * kern_timeout_callwheel_init() - initialize previously reserved callwheel 126 * space. 127 * 128 * This code is called just once, after the space reserved for the 129 * callout wheel has been finalized. 130 */ 131 void 132 kern_timeout_callwheel_init(void) 133 { 134 int i; 135 136 SLIST_INIT(&callfree); 137 for (i = 0; i < ncallout; i++) { 138 callout_init(&callout[i], 0); 139 callout[i].c_flags = CALLOUT_LOCAL_ALLOC; 140 SLIST_INSERT_HEAD(&callfree, &callout[i], c_links.sle); 141 } 142 for (i = 0; i < callwheelsize; i++) { 143 TAILQ_INIT(&callwheel[i]); 144 } 145 mtx_init(&callout_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE); 146 } 147 148 /* 149 * The callout mechanism is based on the work of Adam M. Costello and 150 * George Varghese, published in a technical report entitled "Redesigning 151 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 152 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 153 * used in this implementation was published by G. Varghese and T. Lauck in 154 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 155 * the Efficient Implementation of a Timer Facility" in the Proceedings of 156 * the 11th ACM Annual Symposium on Operating Systems Principles, 157 * Austin, Texas Nov 1987. 158 */ 159 160 /* 161 * Software (low priority) clock interrupt. 162 * Run periodic events from timeout queue. 163 */ 164 void 165 softclock(void *dummy) 166 { 167 struct callout *c; 168 struct callout_tailq *bucket; 169 int curticks; 170 int steps; /* #steps since we last allowed interrupts */ 171 int depth; 172 int mpcalls; 173 int mtxcalls; 174 int gcalls; 175 #ifdef DIAGNOSTIC 176 struct bintime bt1, bt2; 177 struct timespec ts2; 178 static uint64_t maxdt = 36893488147419102LL; /* 2 msec */ 179 static timeout_t *lastfunc; 180 #endif 181 182 #ifndef MAX_SOFTCLOCK_STEPS 183 #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 184 #endif /* MAX_SOFTCLOCK_STEPS */ 185 186 mpcalls = 0; 187 mtxcalls = 0; 188 gcalls = 0; 189 depth = 0; 190 steps = 0; 191 mtx_lock_spin(&callout_lock); 192 while (softticks != ticks) { 193 softticks++; 194 /* 195 * softticks may be modified by hard clock, so cache 196 * it while we work on a given bucket. 197 */ 198 curticks = softticks; 199 bucket = &callwheel[curticks & callwheelmask]; 200 c = TAILQ_FIRST(bucket); 201 while (c) { 202 depth++; 203 if (c->c_time != curticks) { 204 c = TAILQ_NEXT(c, c_links.tqe); 205 ++steps; 206 if (steps >= MAX_SOFTCLOCK_STEPS) { 207 nextsoftcheck = c; 208 /* Give interrupts a chance. */ 209 mtx_unlock_spin(&callout_lock); 210 ; /* nothing */ 211 mtx_lock_spin(&callout_lock); 212 c = nextsoftcheck; 213 steps = 0; 214 } 215 } else { 216 void (*c_func)(void *); 217 void *c_arg; 218 struct mtx *c_mtx; 219 int c_flags; 220 221 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 222 TAILQ_REMOVE(bucket, c, c_links.tqe); 223 c_func = c->c_func; 224 c_arg = c->c_arg; 225 c_mtx = c->c_mtx; 226 c_flags = c->c_flags; 227 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 228 c->c_func = NULL; 229 c->c_flags = CALLOUT_LOCAL_ALLOC; 230 SLIST_INSERT_HEAD(&callfree, c, 231 c_links.sle); 232 curr_callout = NULL; 233 } else { 234 c->c_flags = 235 (c->c_flags & ~CALLOUT_PENDING); 236 curr_callout = c; 237 } 238 curr_cancelled = 0; 239 mtx_unlock_spin(&callout_lock); 240 if (c_mtx != NULL) { 241 mtx_lock(c_mtx); 242 /* 243 * The callout may have been cancelled 244 * while we switched locks. 245 */ 246 if (curr_cancelled) { 247 mtx_unlock(c_mtx); 248 goto skip; 249 } 250 /* The callout cannot be stopped now. */ 251 curr_cancelled = 1; 252 253 if (c_mtx == &Giant) { 254 gcalls++; 255 CTR3(KTR_CALLOUT, 256 "callout %p func %p arg %p", 257 c, c_func, c_arg); 258 } else { 259 mtxcalls++; 260 CTR3(KTR_CALLOUT, "callout mtx" 261 " %p func %p arg %p", 262 c, c_func, c_arg); 263 } 264 } else { 265 mpcalls++; 266 CTR3(KTR_CALLOUT, 267 "callout mpsafe %p func %p arg %p", 268 c, c_func, c_arg); 269 } 270 #ifdef DIAGNOSTIC 271 binuptime(&bt1); 272 #endif 273 THREAD_NO_SLEEPING(); 274 c_func(c_arg); 275 THREAD_SLEEPING_OK(); 276 #ifdef DIAGNOSTIC 277 binuptime(&bt2); 278 bintime_sub(&bt2, &bt1); 279 if (bt2.frac > maxdt) { 280 if (lastfunc != c_func || 281 bt2.frac > maxdt * 2) { 282 bintime2timespec(&bt2, &ts2); 283 printf( 284 "Expensive timeout(9) function: %p(%p) %jd.%09ld s\n", 285 c_func, c_arg, 286 (intmax_t)ts2.tv_sec, 287 ts2.tv_nsec); 288 } 289 maxdt = bt2.frac; 290 lastfunc = c_func; 291 } 292 #endif 293 CTR1(KTR_CALLOUT, "callout %p finished", c); 294 if ((c_flags & CALLOUT_RETURNUNLOCKED) == 0) 295 mtx_unlock(c_mtx); 296 skip: 297 mtx_lock_spin(&callout_lock); 298 curr_callout = NULL; 299 if (callout_wait) { 300 /* 301 * There is someone waiting 302 * for the callout to complete. 303 */ 304 callout_wait = 0; 305 mtx_unlock_spin(&callout_lock); 306 wakeup(&callout_wait); 307 mtx_lock_spin(&callout_lock); 308 } 309 steps = 0; 310 c = nextsoftcheck; 311 } 312 } 313 } 314 avg_depth += (depth * 1000 - avg_depth) >> 8; 315 avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8; 316 avg_mtxcalls += (mtxcalls * 1000 - avg_mtxcalls) >> 8; 317 avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8; 318 nextsoftcheck = NULL; 319 mtx_unlock_spin(&callout_lock); 320 } 321 322 /* 323 * timeout -- 324 * Execute a function after a specified length of time. 325 * 326 * untimeout -- 327 * Cancel previous timeout function call. 328 * 329 * callout_handle_init -- 330 * Initialize a handle so that using it with untimeout is benign. 331 * 332 * See AT&T BCI Driver Reference Manual for specification. This 333 * implementation differs from that one in that although an 334 * identification value is returned from timeout, the original 335 * arguments to timeout as well as the identifier are used to 336 * identify entries for untimeout. 337 */ 338 struct callout_handle 339 timeout(ftn, arg, to_ticks) 340 timeout_t *ftn; 341 void *arg; 342 int to_ticks; 343 { 344 struct callout *new; 345 struct callout_handle handle; 346 347 mtx_lock_spin(&callout_lock); 348 349 /* Fill in the next free callout structure. */ 350 new = SLIST_FIRST(&callfree); 351 if (new == NULL) 352 /* XXX Attempt to malloc first */ 353 panic("timeout table full"); 354 SLIST_REMOVE_HEAD(&callfree, c_links.sle); 355 356 callout_reset(new, to_ticks, ftn, arg); 357 358 handle.callout = new; 359 mtx_unlock_spin(&callout_lock); 360 return (handle); 361 } 362 363 void 364 untimeout(ftn, arg, handle) 365 timeout_t *ftn; 366 void *arg; 367 struct callout_handle handle; 368 { 369 370 /* 371 * Check for a handle that was initialized 372 * by callout_handle_init, but never used 373 * for a real timeout. 374 */ 375 if (handle.callout == NULL) 376 return; 377 378 mtx_lock_spin(&callout_lock); 379 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 380 callout_stop(handle.callout); 381 mtx_unlock_spin(&callout_lock); 382 } 383 384 void 385 callout_handle_init(struct callout_handle *handle) 386 { 387 handle->callout = NULL; 388 } 389 390 /* 391 * New interface; clients allocate their own callout structures. 392 * 393 * callout_reset() - establish or change a timeout 394 * callout_stop() - disestablish a timeout 395 * callout_init() - initialize a callout structure so that it can 396 * safely be passed to callout_reset() and callout_stop() 397 * 398 * <sys/callout.h> defines three convenience macros: 399 * 400 * callout_active() - returns truth if callout has not been stopped, 401 * drained, or deactivated since the last time the callout was 402 * reset. 403 * callout_pending() - returns truth if callout is still waiting for timeout 404 * callout_deactivate() - marks the callout as having been serviced 405 */ 406 int 407 callout_reset(c, to_ticks, ftn, arg) 408 struct callout *c; 409 int to_ticks; 410 void (*ftn)(void *); 411 void *arg; 412 { 413 int cancelled = 0; 414 415 #ifdef notyet /* Some callers of timeout() do not hold Giant. */ 416 if (c->c_mtx != NULL) 417 mtx_assert(c->c_mtx, MA_OWNED); 418 #endif 419 420 mtx_lock_spin(&callout_lock); 421 if (c == curr_callout) { 422 /* 423 * We're being asked to reschedule a callout which is 424 * currently in progress. If there is a mutex then we 425 * can cancel the callout if it has not really started. 426 */ 427 if (c->c_mtx != NULL && !curr_cancelled) 428 cancelled = curr_cancelled = 1; 429 if (callout_wait) { 430 /* 431 * Someone has called callout_drain to kill this 432 * callout. Don't reschedule. 433 */ 434 CTR4(KTR_CALLOUT, "%s %p func %p arg %p", 435 cancelled ? "cancelled" : "failed to cancel", 436 c, c->c_func, c->c_arg); 437 mtx_unlock_spin(&callout_lock); 438 return (cancelled); 439 } 440 } 441 if (c->c_flags & CALLOUT_PENDING) { 442 if (nextsoftcheck == c) { 443 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 444 } 445 TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, 446 c_links.tqe); 447 448 cancelled = 1; 449 450 /* 451 * Part of the normal "stop a pending callout" process 452 * is to clear the CALLOUT_ACTIVE and CALLOUT_PENDING 453 * flags. We're not going to bother doing that here, 454 * because we're going to be setting those flags ten lines 455 * after this point, and we're holding callout_lock 456 * between now and then. 457 */ 458 } 459 460 /* 461 * We could unlock callout_lock here and lock it again before the 462 * TAILQ_INSERT_TAIL, but there's no point since doing this setup 463 * doesn't take much time. 464 */ 465 if (to_ticks <= 0) 466 to_ticks = 1; 467 468 c->c_arg = arg; 469 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING); 470 c->c_func = ftn; 471 c->c_time = ticks + to_ticks; 472 TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask], 473 c, c_links.tqe); 474 CTR5(KTR_CALLOUT, "%sscheduled %p func %p arg %p in %d", 475 cancelled ? "re" : "", c, c->c_func, c->c_arg, to_ticks); 476 mtx_unlock_spin(&callout_lock); 477 478 return (cancelled); 479 } 480 481 int 482 _callout_stop_safe(c, safe) 483 struct callout *c; 484 int safe; 485 { 486 int use_mtx, sq_locked; 487 488 if (!safe && c->c_mtx != NULL) { 489 #ifdef notyet /* Some callers do not hold Giant for Giant-locked callouts. */ 490 mtx_assert(c->c_mtx, MA_OWNED); 491 use_mtx = 1; 492 #else 493 use_mtx = mtx_owned(c->c_mtx); 494 #endif 495 } else { 496 use_mtx = 0; 497 } 498 499 sq_locked = 0; 500 again: 501 mtx_lock_spin(&callout_lock); 502 /* 503 * If the callout isn't pending, it's not on the queue, so 504 * don't attempt to remove it from the queue. We can try to 505 * stop it by other means however. 506 */ 507 if (!(c->c_flags & CALLOUT_PENDING)) { 508 c->c_flags &= ~CALLOUT_ACTIVE; 509 510 /* 511 * If it wasn't on the queue and it isn't the current 512 * callout, then we can't stop it, so just bail. 513 */ 514 if (c != curr_callout) { 515 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 516 c, c->c_func, c->c_arg); 517 mtx_unlock_spin(&callout_lock); 518 if (sq_locked) 519 sleepq_release(&callout_wait); 520 return (0); 521 } 522 523 if (safe) { 524 /* 525 * The current callout is running (or just 526 * about to run) and blocking is allowed, so 527 * just wait for the current invocation to 528 * finish. 529 */ 530 while (c == curr_callout) { 531 532 /* 533 * Use direct calls to sleepqueue interface 534 * instead of cv/msleep in order to avoid 535 * a LOR between callout_lock and sleepqueue 536 * chain spinlocks. This piece of code 537 * emulates a msleep_spin() call actually. 538 * 539 * If we already have the sleepqueue chain 540 * locked, then we can safely block. If we 541 * don't already have it locked, however, 542 * we have to drop the callout_lock to lock 543 * it. This opens several races, so we 544 * restart at the beginning once we have 545 * both locks. If nothing has changed, then 546 * we will end up back here with sq_locked 547 * set. 548 */ 549 if (!sq_locked) { 550 mtx_unlock_spin(&callout_lock); 551 sleepq_lock(&callout_wait); 552 sq_locked = 1; 553 goto again; 554 } 555 556 callout_wait = 1; 557 DROP_GIANT(); 558 mtx_unlock_spin(&callout_lock); 559 sleepq_add(&callout_wait, 560 &callout_lock.lock_object, "codrain", 561 SLEEPQ_SLEEP, 0); 562 sleepq_wait(&callout_wait); 563 sq_locked = 0; 564 565 /* Reacquire locks previously released. */ 566 PICKUP_GIANT(); 567 mtx_lock_spin(&callout_lock); 568 } 569 } else if (use_mtx && !curr_cancelled) { 570 /* 571 * The current callout is waiting for it's 572 * mutex which we hold. Cancel the callout 573 * and return. After our caller drops the 574 * mutex, the callout will be skipped in 575 * softclock(). 576 */ 577 curr_cancelled = 1; 578 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 579 c, c->c_func, c->c_arg); 580 mtx_unlock_spin(&callout_lock); 581 KASSERT(!sq_locked, ("sleepqueue chain locked")); 582 return (1); 583 } 584 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 585 c, c->c_func, c->c_arg); 586 mtx_unlock_spin(&callout_lock); 587 KASSERT(!sq_locked, ("sleepqueue chain still locked")); 588 return (0); 589 } 590 if (sq_locked) 591 sleepq_release(&callout_wait); 592 593 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 594 595 if (nextsoftcheck == c) { 596 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 597 } 598 TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe); 599 600 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 601 c, c->c_func, c->c_arg); 602 603 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 604 c->c_func = NULL; 605 SLIST_INSERT_HEAD(&callfree, c, c_links.sle); 606 } 607 mtx_unlock_spin(&callout_lock); 608 return (1); 609 } 610 611 void 612 callout_init(c, mpsafe) 613 struct callout *c; 614 int mpsafe; 615 { 616 bzero(c, sizeof *c); 617 if (mpsafe) { 618 c->c_mtx = NULL; 619 c->c_flags = CALLOUT_RETURNUNLOCKED; 620 } else { 621 c->c_mtx = &Giant; 622 c->c_flags = 0; 623 } 624 } 625 626 void 627 callout_init_mtx(c, mtx, flags) 628 struct callout *c; 629 struct mtx *mtx; 630 int flags; 631 { 632 bzero(c, sizeof *c); 633 c->c_mtx = mtx; 634 KASSERT((flags & ~(CALLOUT_RETURNUNLOCKED)) == 0, 635 ("callout_init_mtx: bad flags %d", flags)); 636 /* CALLOUT_RETURNUNLOCKED makes no sense without a mutex. */ 637 KASSERT(mtx != NULL || (flags & CALLOUT_RETURNUNLOCKED) == 0, 638 ("callout_init_mtx: CALLOUT_RETURNUNLOCKED with no mutex")); 639 c->c_flags = flags & (CALLOUT_RETURNUNLOCKED); 640 } 641 642 #ifdef APM_FIXUP_CALLTODO 643 /* 644 * Adjust the kernel calltodo timeout list. This routine is used after 645 * an APM resume to recalculate the calltodo timer list values with the 646 * number of hz's we have been sleeping. The next hardclock() will detect 647 * that there are fired timers and run softclock() to execute them. 648 * 649 * Please note, I have not done an exhaustive analysis of what code this 650 * might break. I am motivated to have my select()'s and alarm()'s that 651 * have expired during suspend firing upon resume so that the applications 652 * which set the timer can do the maintanence the timer was for as close 653 * as possible to the originally intended time. Testing this code for a 654 * week showed that resuming from a suspend resulted in 22 to 25 timers 655 * firing, which seemed independant on whether the suspend was 2 hours or 656 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 657 */ 658 void 659 adjust_timeout_calltodo(time_change) 660 struct timeval *time_change; 661 { 662 register struct callout *p; 663 unsigned long delta_ticks; 664 665 /* 666 * How many ticks were we asleep? 667 * (stolen from tvtohz()). 668 */ 669 670 /* Don't do anything */ 671 if (time_change->tv_sec < 0) 672 return; 673 else if (time_change->tv_sec <= LONG_MAX / 1000000) 674 delta_ticks = (time_change->tv_sec * 1000000 + 675 time_change->tv_usec + (tick - 1)) / tick + 1; 676 else if (time_change->tv_sec <= LONG_MAX / hz) 677 delta_ticks = time_change->tv_sec * hz + 678 (time_change->tv_usec + (tick - 1)) / tick + 1; 679 else 680 delta_ticks = LONG_MAX; 681 682 if (delta_ticks > INT_MAX) 683 delta_ticks = INT_MAX; 684 685 /* 686 * Now rip through the timer calltodo list looking for timers 687 * to expire. 688 */ 689 690 /* don't collide with softclock() */ 691 mtx_lock_spin(&callout_lock); 692 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 693 p->c_time -= delta_ticks; 694 695 /* Break if the timer had more time on it than delta_ticks */ 696 if (p->c_time > 0) 697 break; 698 699 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 700 delta_ticks = -p->c_time; 701 } 702 mtx_unlock_spin(&callout_lock); 703 704 return; 705 } 706 #endif /* APM_FIXUP_CALLTODO */
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