2 * Copyright (c) 1982, 1986, 1991, 1993
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34 * From: @(#)kern_clock.c 8.5 (Berkeley) 1/21/94
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD$");
40 #include "opt_kdtrace.h"
42 #include <sys/param.h>
43 #include <sys/systm.h>
45 #include <sys/callout.h>
46 #include <sys/condvar.h>
47 #include <sys/interrupt.h>
48 #include <sys/kernel.h>
51 #include <sys/malloc.h>
52 #include <sys/mutex.h>
55 #include <sys/sleepqueue.h>
56 #include <sys/sysctl.h>
60 #include <machine/cpu.h>
63 SDT_PROVIDER_DEFINE(callout_execute);
64 SDT_PROBE_DEFINE1(callout_execute, kernel, , callout__start,
66 SDT_PROBE_DEFINE1(callout_execute, kernel, , callout__end,
70 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0,
71 "Average number of items examined per softclock call. Units = 1/1000");
72 static int avg_gcalls;
73 SYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0,
74 "Average number of Giant callouts made per softclock call. Units = 1/1000");
75 static int avg_lockcalls;
76 SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls, CTLFLAG_RD, &avg_lockcalls, 0,
77 "Average number of lock callouts made per softclock call. Units = 1/1000");
78 static int avg_mpcalls;
79 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0,
80 "Average number of MP callouts made per softclock call. Units = 1/1000");
83 * allocate more timeout table slots when table overflows.
85 int callwheelsize, callwheelbits, callwheelmask;
88 * The callout cpu migration entity represents informations necessary for
89 * describing the migrating callout to the new callout cpu.
90 * The cached informations are very important for deferring migration when
91 * the migrating callout is already running.
95 void (*ce_migration_func)(void *);
96 void *ce_migration_arg;
98 int ce_migration_ticks;
103 * There is one struct callout_cpu per cpu, holding all relevant
104 * state for the callout processing thread on the individual CPU.
106 * cc_ticks is incremented once per tick in callout_cpu().
107 * It tracks the global 'ticks' but in a way that the individual
108 * threads should not worry about races in the order in which
109 * hardclock() and hardclock_cpu() run on the various CPUs.
110 * cc_softclock is advanced in callout_cpu() to point to the
111 * first entry in cc_callwheel that may need handling. In turn,
112 * a softclock() is scheduled so it can serve the various entries i
113 * such that cc_softclock <= i <= cc_ticks .
114 * XXX maybe cc_softclock and cc_ticks should be volatile ?
116 * cc_ticks is also used in callout_reset_cpu() to determine
117 * when the callout should be served.
120 struct cc_mig_ent cc_migrating_entity;
122 struct callout *cc_callout;
123 struct callout_tailq *cc_callwheel;
124 struct callout_list cc_callfree;
125 struct callout *cc_next;
126 struct callout *cc_curr;
136 #define cc_migration_func cc_migrating_entity.ce_migration_func
137 #define cc_migration_arg cc_migrating_entity.ce_migration_arg
138 #define cc_migration_cpu cc_migrating_entity.ce_migration_cpu
139 #define cc_migration_ticks cc_migrating_entity.ce_migration_ticks
141 struct callout_cpu cc_cpu[MAXCPU];
142 #define CPUBLOCK MAXCPU
143 #define CC_CPU(cpu) (&cc_cpu[(cpu)])
144 #define CC_SELF() CC_CPU(PCPU_GET(cpuid))
146 struct callout_cpu cc_cpu;
147 #define CC_CPU(cpu) &cc_cpu
148 #define CC_SELF() &cc_cpu
150 #define CC_LOCK(cc) mtx_lock_spin(&(cc)->cc_lock)
151 #define CC_UNLOCK(cc) mtx_unlock_spin(&(cc)->cc_lock)
152 #define CC_LOCK_ASSERT(cc) mtx_assert(&(cc)->cc_lock, MA_OWNED)
154 static int timeout_cpu;
155 void (*callout_new_inserted)(int cpu, int ticks) = NULL;
157 static MALLOC_DEFINE(M_CALLOUT, "callout", "Callout datastructures");
161 * cc_curr - If a callout is in progress, it is curr_callout.
162 * If curr_callout is non-NULL, threads waiting in
163 * callout_drain() will be woken up as soon as the
164 * relevant callout completes.
165 * cc_cancel - Changing to 1 with both callout_lock and c_lock held
166 * guarantees that the current callout will not run.
167 * The softclock() function sets this to 0 before it
168 * drops callout_lock to acquire c_lock, and it calls
169 * the handler only if curr_cancelled is still 0 after
170 * c_lock is successfully acquired.
171 * cc_waiting - If a thread is waiting in callout_drain(), then
172 * callout_wait is nonzero. Set only when
173 * curr_callout is non-NULL.
177 * Resets the migration entity tied to a specific callout cpu.
180 cc_cme_cleanup(struct callout_cpu *cc)
184 cc->cc_migration_cpu = CPUBLOCK;
185 cc->cc_migration_ticks = 0;
186 cc->cc_migration_func = NULL;
187 cc->cc_migration_arg = NULL;
192 * Checks if migration is requested by a specific callout cpu.
195 cc_cme_migrating(struct callout_cpu *cc)
199 return (cc->cc_migration_cpu != CPUBLOCK);
206 * kern_timeout_callwheel_alloc() - kernel low level callwheel initialization
208 * This code is called very early in the kernel initialization sequence,
209 * and may be called more then once.
212 kern_timeout_callwheel_alloc(caddr_t v)
214 struct callout_cpu *cc;
216 timeout_cpu = PCPU_GET(cpuid);
217 cc = CC_CPU(timeout_cpu);
219 * Calculate callout wheel size
221 for (callwheelsize = 1, callwheelbits = 0;
222 callwheelsize < ncallout;
223 callwheelsize <<= 1, ++callwheelbits)
225 callwheelmask = callwheelsize - 1;
227 cc->cc_callout = (struct callout *)v;
228 v = (caddr_t)(cc->cc_callout + ncallout);
229 cc->cc_callwheel = (struct callout_tailq *)v;
230 v = (caddr_t)(cc->cc_callwheel + callwheelsize);
235 callout_cpu_init(struct callout_cpu *cc)
240 mtx_init(&cc->cc_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE);
241 SLIST_INIT(&cc->cc_callfree);
242 for (i = 0; i < callwheelsize; i++) {
243 TAILQ_INIT(&cc->cc_callwheel[i]);
246 if (cc->cc_callout == NULL)
248 for (i = 0; i < ncallout; i++) {
249 c = &cc->cc_callout[i];
251 c->c_flags = CALLOUT_LOCAL_ALLOC;
252 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle);
258 * Switches the cpu tied to a specific callout.
259 * The function expects a locked incoming callout cpu and returns with
260 * locked outcoming callout cpu.
262 static struct callout_cpu *
263 callout_cpu_switch(struct callout *c, struct callout_cpu *cc, int new_cpu)
265 struct callout_cpu *new_cc;
267 MPASS(c != NULL && cc != NULL);
271 * Avoid interrupts and preemption firing after the callout cpu
272 * is blocked in order to avoid deadlocks as the new thread
273 * may be willing to acquire the callout cpu lock.
278 new_cc = CC_CPU(new_cpu);
287 * kern_timeout_callwheel_init() - initialize previously reserved callwheel
290 * This code is called just once, after the space reserved for the
291 * callout wheel has been finalized.
294 kern_timeout_callwheel_init(void)
296 callout_cpu_init(CC_CPU(timeout_cpu));
300 * Start standard softclock thread.
303 start_softclock(void *dummy)
305 struct callout_cpu *cc;
310 cc = CC_CPU(timeout_cpu);
311 if (swi_add(&clk_intr_event, "clock", softclock, cc, SWI_CLOCK,
312 INTR_MPSAFE, &cc->cc_cookie))
313 panic("died while creating standard software ithreads");
316 if (cpu == timeout_cpu)
319 if (swi_add(NULL, "clock", softclock, cc, SWI_CLOCK,
320 INTR_MPSAFE, &cc->cc_cookie))
321 panic("died while creating standard software ithreads");
322 cc->cc_callout = NULL; /* Only cpu0 handles timeout(). */
323 cc->cc_callwheel = malloc(
324 sizeof(struct callout_tailq) * callwheelsize, M_CALLOUT,
326 callout_cpu_init(cc);
331 SYSINIT(start_softclock, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_softclock, NULL);
336 struct callout_cpu *cc;
341 * Process callouts at a very low cpu priority, so we don't keep the
342 * relatively high clock interrupt priority any longer than necessary.
346 mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET);
347 cc->cc_firsttick = cc->cc_ticks = ticks;
348 for (; (cc->cc_softticks - cc->cc_ticks) <= 0; cc->cc_softticks++) {
349 bucket = cc->cc_softticks & callwheelmask;
350 if (!TAILQ_EMPTY(&cc->cc_callwheel[bucket])) {
355 mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET);
357 * swi_sched acquires the thread lock, so we don't want to call it
358 * with cc_lock held; incorrect locking order.
361 swi_sched(cc->cc_cookie, 0);
365 callout_tickstofirst(int limit)
367 struct callout_cpu *cc;
369 struct callout_tailq *sc;
374 mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET);
375 curticks = cc->cc_ticks;
376 while( skip < ncallout && skip < limit ) {
377 sc = &cc->cc_callwheel[ (curticks+skip) & callwheelmask ];
378 /* search scanning ticks */
379 TAILQ_FOREACH( c, sc, c_links.tqe ){
380 if (c->c_time - curticks <= ncallout)
386 cc->cc_firsttick = curticks + skip;
387 mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET);
391 static struct callout_cpu *
392 callout_lock(struct callout *c)
394 struct callout_cpu *cc;
400 if (cpu == CPUBLOCK) {
401 while (c->c_cpu == CPUBLOCK)
416 callout_cc_add(struct callout *c, struct callout_cpu *cc, int to_ticks,
417 void (*func)(void *), void *arg, int cpu)
425 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING);
427 c->c_time = ticks + to_ticks;
428 TAILQ_INSERT_TAIL(&cc->cc_callwheel[c->c_time & callwheelmask],
430 if ((c->c_time - cc->cc_firsttick) < 0 &&
431 callout_new_inserted != NULL) {
432 cc->cc_firsttick = c->c_time;
433 (*callout_new_inserted)(cpu,
434 to_ticks + (ticks - cc->cc_ticks));
439 callout_cc_del(struct callout *c, struct callout_cpu *cc)
442 if ((c->c_flags & CALLOUT_LOCAL_ALLOC) == 0)
445 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle);
449 softclock_call_cc(struct callout *c, struct callout_cpu *cc, int *mpcalls,
450 int *lockcalls, int *gcalls)
452 void (*c_func)(void *);
454 struct lock_class *class;
455 struct lock_object *c_lock;
456 int c_flags, sharedlock;
458 struct callout_cpu *new_cc;
459 void (*new_func)(void *);
461 int new_cpu, new_ticks;
464 struct bintime bt1, bt2;
466 static uint64_t maxdt = 36893488147419102LL; /* 2 msec */
467 static timeout_t *lastfunc;
470 KASSERT((c->c_flags & (CALLOUT_PENDING | CALLOUT_ACTIVE)) ==
471 (CALLOUT_PENDING | CALLOUT_ACTIVE),
472 ("softclock_call_cc: pend|act %p %x", c, c->c_flags));
473 class = (c->c_lock != NULL) ? LOCK_CLASS(c->c_lock) : NULL;
474 sharedlock = (c->c_flags & CALLOUT_SHAREDLOCK) ? 0 : 1;
478 c_flags = c->c_flags;
479 if (c->c_flags & CALLOUT_LOCAL_ALLOC)
480 c->c_flags = CALLOUT_LOCAL_ALLOC;
482 c->c_flags &= ~CALLOUT_PENDING;
486 if (c_lock != NULL) {
487 class->lc_lock(c_lock, sharedlock);
489 * The callout may have been cancelled
490 * while we switched locks.
493 class->lc_unlock(c_lock);
496 /* The callout cannot be stopped now. */
499 if (c_lock == &Giant.lock_object) {
501 CTR3(KTR_CALLOUT, "callout %p func %p arg %p",
505 CTR3(KTR_CALLOUT, "callout lock %p func %p arg %p",
510 CTR3(KTR_CALLOUT, "callout mpsafe %p func %p arg %p",
516 THREAD_NO_SLEEPING();
517 SDT_PROBE(callout_execute, kernel, , callout__start, c, 0, 0, 0, 0);
519 SDT_PROBE(callout_execute, kernel, , callout__end, c, 0, 0, 0, 0);
520 THREAD_SLEEPING_OK();
523 bintime_sub(&bt2, &bt1);
524 if (bt2.frac > maxdt) {
525 if (lastfunc != c_func || bt2.frac > maxdt * 2) {
526 bintime2timespec(&bt2, &ts2);
528 "Expensive timeout(9) function: %p(%p) %jd.%09ld s\n",
529 c_func, c_arg, (intmax_t)ts2.tv_sec, ts2.tv_nsec);
535 CTR1(KTR_CALLOUT, "callout %p finished", c);
536 if ((c_flags & CALLOUT_RETURNUNLOCKED) == 0)
537 class->lc_unlock(c_lock);
540 KASSERT(cc->cc_curr == c, ("mishandled cc_curr"));
542 if (cc->cc_waiting) {
544 * There is someone waiting for the
545 * callout to complete.
546 * If the callout was scheduled for
547 * migration just cancel it.
549 if (cc_cme_migrating(cc)) {
553 * It should be assert here that the callout is not
554 * destroyed but that is not easy.
556 c->c_flags &= ~CALLOUT_DFRMIGRATION;
560 wakeup(&cc->cc_waiting);
562 } else if (cc_cme_migrating(cc)) {
563 KASSERT((c_flags & CALLOUT_LOCAL_ALLOC) == 0,
564 ("Migrating legacy callout %p", c));
567 * If the callout was scheduled for
568 * migration just perform it now.
570 new_cpu = cc->cc_migration_cpu;
571 new_ticks = cc->cc_migration_ticks;
572 new_func = cc->cc_migration_func;
573 new_arg = cc->cc_migration_arg;
577 * It should be assert here that the callout is not destroyed
578 * but that is not easy.
580 * As first thing, handle deferred callout stops.
582 if ((c->c_flags & CALLOUT_DFRMIGRATION) == 0) {
584 "deferred cancelled %p func %p arg %p",
585 c, new_func, new_arg);
586 callout_cc_del(c, cc);
589 c->c_flags &= ~CALLOUT_DFRMIGRATION;
591 new_cc = callout_cpu_switch(c, cc, new_cpu);
592 callout_cc_add(c, new_cc, new_ticks, new_func, new_arg,
597 panic("migration should not happen");
601 * If the current callout is locally allocated (from
602 * timeout(9)) then put it on the freelist.
604 * Note: we need to check the cached copy of c_flags because
605 * if it was not local, then it's not safe to deref the
608 KASSERT((c_flags & CALLOUT_LOCAL_ALLOC) == 0 ||
609 c->c_flags == CALLOUT_LOCAL_ALLOC,
610 ("corrupted callout"));
611 if (c_flags & CALLOUT_LOCAL_ALLOC)
612 callout_cc_del(c, cc);
616 * The callout mechanism is based on the work of Adam M. Costello and
617 * George Varghese, published in a technical report entitled "Redesigning
618 * the BSD Callout and Timer Facilities" and modified slightly for inclusion
619 * in FreeBSD by Justin T. Gibbs. The original work on the data structures
620 * used in this implementation was published by G. Varghese and T. Lauck in
621 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for
622 * the Efficient Implementation of a Timer Facility" in the Proceedings of
623 * the 11th ACM Annual Symposium on Operating Systems Principles,
624 * Austin, Texas Nov 1987.
628 * Software (low priority) clock interrupt.
629 * Run periodic events from timeout queue.
634 struct callout_cpu *cc;
636 struct callout_tailq *bucket;
638 int steps; /* #steps since we last allowed interrupts */
644 #ifndef MAX_SOFTCLOCK_STEPS
645 #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */
646 #endif /* MAX_SOFTCLOCK_STEPS */
653 cc = (struct callout_cpu *)arg;
655 while (cc->cc_softticks - 1 != cc->cc_ticks) {
657 * cc_softticks may be modified by hard clock, so cache
658 * it while we work on a given bucket.
660 curticks = cc->cc_softticks;
662 bucket = &cc->cc_callwheel[curticks & callwheelmask];
663 c = TAILQ_FIRST(bucket);
666 if (c->c_time != curticks) {
667 c = TAILQ_NEXT(c, c_links.tqe);
669 if (steps >= MAX_SOFTCLOCK_STEPS) {
671 /* Give interrupts a chance. */
679 cc->cc_next = TAILQ_NEXT(c, c_links.tqe);
680 TAILQ_REMOVE(bucket, c, c_links.tqe);
681 softclock_call_cc(c, cc, &mpcalls,
682 &lockcalls, &gcalls);
688 avg_depth += (depth * 1000 - avg_depth) >> 8;
689 avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8;
690 avg_lockcalls += (lockcalls * 1000 - avg_lockcalls) >> 8;
691 avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8;
698 * Execute a function after a specified length of time.
701 * Cancel previous timeout function call.
703 * callout_handle_init --
704 * Initialize a handle so that using it with untimeout is benign.
706 * See AT&T BCI Driver Reference Manual for specification. This
707 * implementation differs from that one in that although an
708 * identification value is returned from timeout, the original
709 * arguments to timeout as well as the identifier are used to
710 * identify entries for untimeout.
712 struct callout_handle
713 timeout(ftn, arg, to_ticks)
718 struct callout_cpu *cc;
720 struct callout_handle handle;
722 cc = CC_CPU(timeout_cpu);
724 /* Fill in the next free callout structure. */
725 new = SLIST_FIRST(&cc->cc_callfree);
727 /* XXX Attempt to malloc first */
728 panic("timeout table full");
729 SLIST_REMOVE_HEAD(&cc->cc_callfree, c_links.sle);
730 callout_reset(new, to_ticks, ftn, arg);
731 handle.callout = new;
738 untimeout(ftn, arg, handle)
741 struct callout_handle handle;
743 struct callout_cpu *cc;
746 * Check for a handle that was initialized
747 * by callout_handle_init, but never used
748 * for a real timeout.
750 if (handle.callout == NULL)
753 cc = callout_lock(handle.callout);
754 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg)
755 callout_stop(handle.callout);
760 callout_handle_init(struct callout_handle *handle)
762 handle->callout = NULL;
766 * New interface; clients allocate their own callout structures.
768 * callout_reset() - establish or change a timeout
769 * callout_stop() - disestablish a timeout
770 * callout_init() - initialize a callout structure so that it can
771 * safely be passed to callout_reset() and callout_stop()
773 * <sys/callout.h> defines three convenience macros:
775 * callout_active() - returns truth if callout has not been stopped,
776 * drained, or deactivated since the last time the callout was
778 * callout_pending() - returns truth if callout is still waiting for timeout
779 * callout_deactivate() - marks the callout as having been serviced
782 callout_reset_on(struct callout *c, int to_ticks, void (*ftn)(void *),
785 struct callout_cpu *cc;
789 * Don't allow migration of pre-allocated callouts lest they
792 if (c->c_flags & CALLOUT_LOCAL_ALLOC)
794 cc = callout_lock(c);
795 if (cc->cc_curr == c) {
797 * We're being asked to reschedule a callout which is
798 * currently in progress. If there is a lock then we
799 * can cancel the callout if it has not really started.
801 if (c->c_lock != NULL && !cc->cc_cancel)
802 cancelled = cc->cc_cancel = 1;
803 if (cc->cc_waiting) {
805 * Someone has called callout_drain to kill this
806 * callout. Don't reschedule.
808 CTR4(KTR_CALLOUT, "%s %p func %p arg %p",
809 cancelled ? "cancelled" : "failed to cancel",
810 c, c->c_func, c->c_arg);
815 if (c->c_flags & CALLOUT_PENDING) {
816 if (cc->cc_next == c) {
817 cc->cc_next = TAILQ_NEXT(c, c_links.tqe);
819 TAILQ_REMOVE(&cc->cc_callwheel[c->c_time & callwheelmask], c,
823 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
828 * If the callout must migrate try to perform it immediately.
829 * If the callout is currently running, just defer the migration
830 * to a more appropriate moment.
832 if (c->c_cpu != cpu) {
833 if (cc->cc_curr == c) {
834 cc->cc_migration_cpu = cpu;
835 cc->cc_migration_ticks = to_ticks;
836 cc->cc_migration_func = ftn;
837 cc->cc_migration_arg = arg;
838 c->c_flags |= CALLOUT_DFRMIGRATION;
840 "migration of %p func %p arg %p in %d to %u deferred",
841 c, c->c_func, c->c_arg, to_ticks, cpu);
845 cc = callout_cpu_switch(c, cc, cpu);
849 callout_cc_add(c, cc, to_ticks, ftn, arg, cpu);
850 CTR5(KTR_CALLOUT, "%sscheduled %p func %p arg %p in %d",
851 cancelled ? "re" : "", c, c->c_func, c->c_arg, to_ticks);
858 * Common idioms that can be optimized in the future.
861 callout_schedule_on(struct callout *c, int to_ticks, int cpu)
863 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, cpu);
867 callout_schedule(struct callout *c, int to_ticks)
869 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, c->c_cpu);
873 _callout_stop_safe(c, safe)
877 struct callout_cpu *cc, *old_cc;
878 struct lock_class *class;
879 int use_lock, sq_locked;
882 * Some old subsystems don't hold Giant while running a callout_stop(),
883 * so just discard this check for the moment.
885 if (!safe && c->c_lock != NULL) {
886 if (c->c_lock == &Giant.lock_object)
887 use_lock = mtx_owned(&Giant);
890 class = LOCK_CLASS(c->c_lock);
891 class->lc_assert(c->c_lock, LA_XLOCKED);
899 cc = callout_lock(c);
902 * If the callout was migrating while the callout cpu lock was
903 * dropped, just drop the sleepqueue lock and check the states
906 if (sq_locked != 0 && cc != old_cc) {
909 sleepq_release(&old_cc->cc_waiting);
914 panic("migration should not happen");
919 * If the callout isn't pending, it's not on the queue, so
920 * don't attempt to remove it from the queue. We can try to
921 * stop it by other means however.
923 if (!(c->c_flags & CALLOUT_PENDING)) {
924 c->c_flags &= ~CALLOUT_ACTIVE;
927 * If it wasn't on the queue and it isn't the current
928 * callout, then we can't stop it, so just bail.
930 if (cc->cc_curr != c) {
931 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p",
932 c, c->c_func, c->c_arg);
935 sleepq_release(&cc->cc_waiting);
941 * The current callout is running (or just
942 * about to run) and blocking is allowed, so
943 * just wait for the current invocation to
946 while (cc->cc_curr == c) {
949 * Use direct calls to sleepqueue interface
950 * instead of cv/msleep in order to avoid
951 * a LOR between cc_lock and sleepqueue
952 * chain spinlocks. This piece of code
953 * emulates a msleep_spin() call actually.
955 * If we already have the sleepqueue chain
956 * locked, then we can safely block. If we
957 * don't already have it locked, however,
958 * we have to drop the cc_lock to lock
959 * it. This opens several races, so we
960 * restart at the beginning once we have
961 * both locks. If nothing has changed, then
962 * we will end up back here with sq_locked
967 sleepq_lock(&cc->cc_waiting);
974 * Migration could be cancelled here, but
975 * as long as it is still not sure when it
976 * will be packed up, just let softclock()
982 sleepq_add(&cc->cc_waiting,
983 &cc->cc_lock.lock_object, "codrain",
985 sleepq_wait(&cc->cc_waiting, 0);
989 /* Reacquire locks previously released. */
993 } else if (use_lock && !cc->cc_cancel) {
995 * The current callout is waiting for its
996 * lock which we hold. Cancel the callout
997 * and return. After our caller drops the
998 * lock, the callout will be skipped in
1002 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p",
1003 c, c->c_func, c->c_arg);
1004 KASSERT(!cc_cme_migrating(cc),
1005 ("callout wrongly scheduled for migration"));
1007 KASSERT(!sq_locked, ("sleepqueue chain locked"));
1009 } else if ((c->c_flags & CALLOUT_DFRMIGRATION) != 0) {
1010 c->c_flags &= ~CALLOUT_DFRMIGRATION;
1011 CTR3(KTR_CALLOUT, "postponing stop %p func %p arg %p",
1012 c, c->c_func, c->c_arg);
1016 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p",
1017 c, c->c_func, c->c_arg);
1019 KASSERT(!sq_locked, ("sleepqueue chain still locked"));
1023 sleepq_release(&cc->cc_waiting);
1025 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
1027 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p",
1028 c, c->c_func, c->c_arg);
1029 if (cc->cc_next == c)
1030 cc->cc_next = TAILQ_NEXT(c, c_links.tqe);
1031 TAILQ_REMOVE(&cc->cc_callwheel[c->c_time & callwheelmask], c,
1033 callout_cc_del(c, cc);
1040 callout_init(c, mpsafe)
1044 bzero(c, sizeof *c);
1047 c->c_flags = CALLOUT_RETURNUNLOCKED;
1049 c->c_lock = &Giant.lock_object;
1052 c->c_cpu = timeout_cpu;
1056 _callout_init_lock(c, lock, flags)
1058 struct lock_object *lock;
1061 bzero(c, sizeof *c);
1063 KASSERT((flags & ~(CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK)) == 0,
1064 ("callout_init_lock: bad flags %d", flags));
1065 KASSERT(lock != NULL || (flags & CALLOUT_RETURNUNLOCKED) == 0,
1066 ("callout_init_lock: CALLOUT_RETURNUNLOCKED with no lock"));
1067 KASSERT(lock == NULL || !(LOCK_CLASS(lock)->lc_flags &
1068 (LC_SPINLOCK | LC_SLEEPABLE)), ("%s: invalid lock class",
1070 c->c_flags = flags & (CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK);
1071 c->c_cpu = timeout_cpu;
1074 #ifdef APM_FIXUP_CALLTODO
1076 * Adjust the kernel calltodo timeout list. This routine is used after
1077 * an APM resume to recalculate the calltodo timer list values with the
1078 * number of hz's we have been sleeping. The next hardclock() will detect
1079 * that there are fired timers and run softclock() to execute them.
1081 * Please note, I have not done an exhaustive analysis of what code this
1082 * might break. I am motivated to have my select()'s and alarm()'s that
1083 * have expired during suspend firing upon resume so that the applications
1084 * which set the timer can do the maintanence the timer was for as close
1085 * as possible to the originally intended time. Testing this code for a
1086 * week showed that resuming from a suspend resulted in 22 to 25 timers
1087 * firing, which seemed independant on whether the suspend was 2 hours or
1088 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu>
1091 adjust_timeout_calltodo(time_change)
1092 struct timeval *time_change;
1094 register struct callout *p;
1095 unsigned long delta_ticks;
1098 * How many ticks were we asleep?
1099 * (stolen from tvtohz()).
1102 /* Don't do anything */
1103 if (time_change->tv_sec < 0)
1105 else if (time_change->tv_sec <= LONG_MAX / 1000000)
1106 delta_ticks = (time_change->tv_sec * 1000000 +
1107 time_change->tv_usec + (tick - 1)) / tick + 1;
1108 else if (time_change->tv_sec <= LONG_MAX / hz)
1109 delta_ticks = time_change->tv_sec * hz +
1110 (time_change->tv_usec + (tick - 1)) / tick + 1;
1112 delta_ticks = LONG_MAX;
1114 if (delta_ticks > INT_MAX)
1115 delta_ticks = INT_MAX;
1118 * Now rip through the timer calltodo list looking for timers
1122 /* don't collide with softclock() */
1124 for (p = calltodo.c_next; p != NULL; p = p->c_next) {
1125 p->c_time -= delta_ticks;
1127 /* Break if the timer had more time on it than delta_ticks */
1131 /* take back the ticks the timer didn't use (p->c_time <= 0) */
1132 delta_ticks = -p->c_time;
1138 #endif /* APM_FIXUP_CALLTODO */