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/6.4/sys/kern/kern_timeout.c 181936 2008-08-20 19:07:21Z 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 if ((c_flags & CALLOUT_RETURNUNLOCKED) == 0)
294 mtx_unlock(c_mtx);
295 skip:
296 mtx_lock_spin(&callout_lock);
297 curr_callout = NULL;
298 if (callout_wait) {
299 /*
300 * There is someone waiting
301 * for the callout to complete.
302 */
303 callout_wait = 0;
304 mtx_unlock_spin(&callout_lock);
305 wakeup(&callout_wait);
306 mtx_lock_spin(&callout_lock);
307 }
308 steps = 0;
309 c = nextsoftcheck;
310 }
311 }
312 }
313 avg_depth += (depth * 1000 - avg_depth) >> 8;
314 avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8;
315 avg_mtxcalls += (mtxcalls * 1000 - avg_mtxcalls) >> 8;
316 avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8;
317 nextsoftcheck = NULL;
318 mtx_unlock_spin(&callout_lock);
319 }
320
321 /*
322 * timeout --
323 * Execute a function after a specified length of time.
324 *
325 * untimeout --
326 * Cancel previous timeout function call.
327 *
328 * callout_handle_init --
329 * Initialize a handle so that using it with untimeout is benign.
330 *
331 * See AT&T BCI Driver Reference Manual for specification. This
332 * implementation differs from that one in that although an
333 * identification value is returned from timeout, the original
334 * arguments to timeout as well as the identifier are used to
335 * identify entries for untimeout.
336 */
337 struct callout_handle
338 timeout(ftn, arg, to_ticks)
339 timeout_t *ftn;
340 void *arg;
341 int to_ticks;
342 {
343 struct callout *new;
344 struct callout_handle handle;
345
346 mtx_lock_spin(&callout_lock);
347
348 /* Fill in the next free callout structure. */
349 new = SLIST_FIRST(&callfree);
350 if (new == NULL)
351 /* XXX Attempt to malloc first */
352 panic("timeout table full");
353 SLIST_REMOVE_HEAD(&callfree, c_links.sle);
354
355 callout_reset(new, to_ticks, ftn, arg);
356
357 handle.callout = new;
358 mtx_unlock_spin(&callout_lock);
359 return (handle);
360 }
361
362 void
363 untimeout(ftn, arg, handle)
364 timeout_t *ftn;
365 void *arg;
366 struct callout_handle handle;
367 {
368
369 /*
370 * Check for a handle that was initialized
371 * by callout_handle_init, but never used
372 * for a real timeout.
373 */
374 if (handle.callout == NULL)
375 return;
376
377 mtx_lock_spin(&callout_lock);
378 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg)
379 callout_stop(handle.callout);
380 mtx_unlock_spin(&callout_lock);
381 }
382
383 void
384 callout_handle_init(struct callout_handle *handle)
385 {
386 handle->callout = NULL;
387 }
388
389 /*
390 * New interface; clients allocate their own callout structures.
391 *
392 * callout_reset() - establish or change a timeout
393 * callout_stop() - disestablish a timeout
394 * callout_init() - initialize a callout structure so that it can
395 * safely be passed to callout_reset() and callout_stop()
396 *
397 * <sys/callout.h> defines three convenience macros:
398 *
399 * callout_active() - returns truth if callout has not been stopped,
400 * drained, or deactivated since the last time the callout was
401 * reset.
402 * callout_pending() - returns truth if callout is still waiting for timeout
403 * callout_deactivate() - marks the callout as having been serviced
404 */
405 int
406 callout_reset(c, to_ticks, ftn, arg)
407 struct callout *c;
408 int to_ticks;
409 void (*ftn)(void *);
410 void *arg;
411 {
412 int cancelled = 0;
413
414 #ifdef notyet /* Some callers of timeout() do not hold Giant. */
415 if (c->c_mtx != NULL)
416 mtx_assert(c->c_mtx, MA_OWNED);
417 #endif
418
419 mtx_lock_spin(&callout_lock);
420 if (c == curr_callout) {
421 /*
422 * We're being asked to reschedule a callout which is
423 * currently in progress. If there is a mutex then we
424 * can cancel the callout if it has not really started.
425 */
426 if (c->c_mtx != NULL && !curr_cancelled)
427 cancelled = curr_cancelled = 1;
428 if (callout_wait) {
429 /*
430 * Someone has called callout_drain to kill this
431 * callout. Don't reschedule.
432 */
433 CTR4(KTR_CALLOUT, "%s %p func %p arg %p",
434 cancelled ? "cancelled" : "failed to cancel",
435 c, c->c_func, c->c_arg);
436 mtx_unlock_spin(&callout_lock);
437 return (cancelled);
438 }
439 }
440 if (c->c_flags & CALLOUT_PENDING) {
441 if (nextsoftcheck == c) {
442 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
443 }
444 TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c,
445 c_links.tqe);
446
447 cancelled = 1;
448
449 /*
450 * Part of the normal "stop a pending callout" process
451 * is to clear the CALLOUT_ACTIVE and CALLOUT_PENDING
452 * flags. We're not going to bother doing that here,
453 * because we're going to be setting those flags ten lines
454 * after this point, and we're holding callout_lock
455 * between now and then.
456 */
457 }
458
459 /*
460 * We could unlock callout_lock here and lock it again before the
461 * TAILQ_INSERT_TAIL, but there's no point since doing this setup
462 * doesn't take much time.
463 */
464 if (to_ticks <= 0)
465 to_ticks = 1;
466
467 c->c_arg = arg;
468 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING);
469 c->c_func = ftn;
470 c->c_time = ticks + to_ticks;
471 TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask],
472 c, c_links.tqe);
473 CTR5(KTR_CALLOUT, "%sscheduled %p func %p arg %p in %d",
474 cancelled ? "re" : "", c, c->c_func, c->c_arg, to_ticks);
475 mtx_unlock_spin(&callout_lock);
476
477 return (cancelled);
478 }
479
480 int
481 _callout_stop_safe(c, safe)
482 struct callout *c;
483 int safe;
484 {
485 int use_mtx, sq_locked;
486
487 if (!safe && c->c_mtx != NULL) {
488 #ifdef notyet /* Some callers do not hold Giant for Giant-locked callouts. */
489 mtx_assert(c->c_mtx, MA_OWNED);
490 use_mtx = 1;
491 #else
492 use_mtx = mtx_owned(c->c_mtx);
493 #endif
494 } else {
495 use_mtx = 0;
496 }
497
498 sq_locked = 0;
499 again:
500 mtx_lock_spin(&callout_lock);
501 /*
502 * If the callout isn't pending, it's not on the queue, so
503 * don't attempt to remove it from the queue. We can try to
504 * stop it by other means however.
505 */
506 if (!(c->c_flags & CALLOUT_PENDING)) {
507 c->c_flags &= ~CALLOUT_ACTIVE;
508
509 /*
510 * If it wasn't on the queue and it isn't the current
511 * callout, then we can't stop it, so just bail.
512 */
513 if (c != curr_callout) {
514 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p",
515 c, c->c_func, c->c_arg);
516 mtx_unlock_spin(&callout_lock);
517 if (sq_locked)
518 sleepq_release(&callout_wait);
519 return (0);
520 }
521
522 if (safe) {
523 /*
524 * The current callout is running (or just
525 * about to run) and blocking is allowed, so
526 * just wait for the current invocation to
527 * finish.
528 */
529 while (c == curr_callout) {
530
531 /*
532 * Use direct calls to sleepqueue interface
533 * instead of cv/msleep in order to avoid
534 * a LOR between callout_lock and sleepqueue
535 * chain spinlocks. This piece of code
536 * emulates a msleep_spin() call actually.
537 *
538 * If we already have the sleepqueue chain
539 * locked, then we can safely block. If we
540 * don't already have it locked, however,
541 * we have to drop the callout_lock to lock
542 * it. This opens several races, so we
543 * restart at the beginning once we have
544 * both locks. If nothing has changed, then
545 * we will end up back here with sq_locked
546 * set.
547 */
548 if (!sq_locked) {
549 mtx_unlock_spin(&callout_lock);
550 sleepq_lock(&callout_wait);
551 sq_locked = 1;
552 goto again;
553 }
554
555 callout_wait = 1;
556 DROP_GIANT();
557 mtx_unlock_spin(&callout_lock);
558 sleepq_add(&callout_wait,
559 &callout_lock.mtx_object, "codrain",
560 SLEEPQ_MSLEEP, 0);
561 sleepq_wait(&callout_wait);
562 sq_locked = 0;
563
564 /* Reacquire locks previously released. */
565 PICKUP_GIANT();
566 mtx_lock_spin(&callout_lock);
567 }
568 } else if (use_mtx && !curr_cancelled) {
569 /*
570 * The current callout is waiting for it's
571 * mutex which we hold. Cancel the callout
572 * and return. After our caller drops the
573 * mutex, the callout will be skipped in
574 * softclock().
575 */
576 curr_cancelled = 1;
577 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p",
578 c, c->c_func, c->c_arg);
579 mtx_unlock_spin(&callout_lock);
580 KASSERT(!sq_locked, ("sleepqueue chain locked"));
581 return (1);
582 }
583 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p",
584 c, c->c_func, c->c_arg);
585 mtx_unlock_spin(&callout_lock);
586 KASSERT(!sq_locked, ("sleepqueue chain still locked"));
587 return (0);
588 }
589 if (sq_locked)
590 sleepq_release(&callout_wait);
591
592 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
593
594 if (nextsoftcheck == c) {
595 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
596 }
597 TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe);
598
599 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p",
600 c, c->c_func, c->c_arg);
601
602 if (c->c_flags & CALLOUT_LOCAL_ALLOC) {
603 c->c_func = NULL;
604 SLIST_INSERT_HEAD(&callfree, c, c_links.sle);
605 }
606 mtx_unlock_spin(&callout_lock);
607 return (1);
608 }
609
610 void
611 callout_init(c, mpsafe)
612 struct callout *c;
613 int mpsafe;
614 {
615 bzero(c, sizeof *c);
616 if (mpsafe) {
617 c->c_mtx = NULL;
618 c->c_flags = CALLOUT_RETURNUNLOCKED;
619 } else {
620 c->c_mtx = &Giant;
621 c->c_flags = 0;
622 }
623 }
624
625 void
626 callout_init_mtx(c, mtx, flags)
627 struct callout *c;
628 struct mtx *mtx;
629 int flags;
630 {
631 bzero(c, sizeof *c);
632 c->c_mtx = mtx;
633 KASSERT((flags & ~CALLOUT_RETURNUNLOCKED) == 0,
634 ("callout_init_mtx: bad flags %d", flags));
635 /* CALLOUT_RETURNUNLOCKED makes no sense without a mutex. */
636 KASSERT(mtx != NULL || (flags & CALLOUT_RETURNUNLOCKED) == 0,
637 ("callout_init_mtx: CALLOUT_RETURNUNLOCKED with no mutex"));
638 c->c_flags = flags & CALLOUT_RETURNUNLOCKED;
639 }
640
641 #ifdef APM_FIXUP_CALLTODO
642 /*
643 * Adjust the kernel calltodo timeout list. This routine is used after
644 * an APM resume to recalculate the calltodo timer list values with the
645 * number of hz's we have been sleeping. The next hardclock() will detect
646 * that there are fired timers and run softclock() to execute them.
647 *
648 * Please note, I have not done an exhaustive analysis of what code this
649 * might break. I am motivated to have my select()'s and alarm()'s that
650 * have expired during suspend firing upon resume so that the applications
651 * which set the timer can do the maintanence the timer was for as close
652 * as possible to the originally intended time. Testing this code for a
653 * week showed that resuming from a suspend resulted in 22 to 25 timers
654 * firing, which seemed independant on whether the suspend was 2 hours or
655 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu>
656 */
657 void
658 adjust_timeout_calltodo(time_change)
659 struct timeval *time_change;
660 {
661 register struct callout *p;
662 unsigned long delta_ticks;
663
664 /*
665 * How many ticks were we asleep?
666 * (stolen from tvtohz()).
667 */
668
669 /* Don't do anything */
670 if (time_change->tv_sec < 0)
671 return;
672 else if (time_change->tv_sec <= LONG_MAX / 1000000)
673 delta_ticks = (time_change->tv_sec * 1000000 +
674 time_change->tv_usec + (tick - 1)) / tick + 1;
675 else if (time_change->tv_sec <= LONG_MAX / hz)
676 delta_ticks = time_change->tv_sec * hz +
677 (time_change->tv_usec + (tick - 1)) / tick + 1;
678 else
679 delta_ticks = LONG_MAX;
680
681 if (delta_ticks > INT_MAX)
682 delta_ticks = INT_MAX;
683
684 /*
685 * Now rip through the timer calltodo list looking for timers
686 * to expire.
687 */
688
689 /* don't collide with softclock() */
690 mtx_lock_spin(&callout_lock);
691 for (p = calltodo.c_next; p != NULL; p = p->c_next) {
692 p->c_time -= delta_ticks;
693
694 /* Break if the timer had more time on it than delta_ticks */
695 if (p->c_time > 0)
696 break;
697
698 /* take back the ticks the timer didn't use (p->c_time <= 0) */
699 delta_ticks = -p->c_time;
700 }
701 mtx_unlock_spin(&callout_lock);
702
703 return;
704 }
705 #endif /* APM_FIXUP_CALLTODO */
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