2 * Copyright (c) 2004 John Baldwin <jhb@FreeBSD.org>
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the author nor the names of any co-contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * Implementation of sleep queues used to hold queue of threads blocked on
32 * a wait channel. Sleep queues different from turnstiles in that wait
33 * channels are not owned by anyone, so there is no priority propagation.
34 * Sleep queues can also provide a timeout and can also be interrupted by
35 * signals. That said, there are several similarities between the turnstile
36 * and sleep queue implementations. (Note: turnstiles were implemented
37 * first.) For example, both use a hash table of the same size where each
38 * bucket is referred to as a "chain" that contains both a spin lock and
39 * a linked list of queues. An individual queue is located by using a hash
40 * to pick a chain, locking the chain, and then walking the chain searching
41 * for the queue. This means that a wait channel object does not need to
42 * embed it's queue head just as locks do not embed their turnstile queue
43 * head. Threads also carry around a sleep queue that they lend to the
44 * wait channel when blocking. Just as in turnstiles, the queue includes
45 * a free list of the sleep queues of other threads blocked on the same
46 * wait channel in the case of multiple waiters.
48 * Some additional functionality provided by sleep queues include the
49 * ability to set a timeout. The timeout is managed using a per-thread
50 * callout that resumes a thread if it is asleep. A thread may also
51 * catch signals while it is asleep (aka an interruptible sleep). The
52 * signal code uses sleepq_abort() to interrupt a sleeping thread. Finally,
53 * sleep queues also provide some extra assertions. One is not allowed to
54 * mix the sleep/wakeup and cv APIs for a given wait channel. Also, one
55 * must consistently use the same lock to synchronize with a wait channel,
56 * though this check is currently only a warning for sleep/wakeup due to
57 * pre-existing abuse of that API. The same lock must also be held when
58 * awakening threads, though that is currently only enforced for condition
62 #include <sys/cdefs.h>
63 __FBSDID("$FreeBSD$");
65 #include "opt_sleepqueue_profiling.h"
67 #include "opt_sched.h"
69 #include <sys/param.h>
70 #include <sys/systm.h>
72 #include <sys/kernel.h>
74 #include <sys/mutex.h>
76 #include <sys/sched.h>
77 #include <sys/signalvar.h>
78 #include <sys/sleepqueue.h>
79 #include <sys/sysctl.h>
88 * Constants for the hash table of sleep queue chains. These constants are
89 * the same ones that 4BSD (and possibly earlier versions of BSD) used.
90 * Basically, we ignore the lower 8 bits of the address since most wait
91 * channel pointers are aligned and only look at the next 7 bits for the
92 * hash. SC_TABLESIZE must be a power of two for SC_MASK to work properly.
94 #define SC_TABLESIZE 128 /* Must be power of 2. */
95 #define SC_MASK (SC_TABLESIZE - 1)
97 #define SC_HASH(wc) (((uintptr_t)(wc) >> SC_SHIFT) & SC_MASK)
98 #define SC_LOOKUP(wc) &sleepq_chains[SC_HASH(wc)]
101 * There two different lists of sleep queues. Both lists are connected
102 * via the sq_hash entries. The first list is the sleep queue chain list
103 * that a sleep queue is on when it is attached to a wait channel. The
104 * second list is the free list hung off of a sleep queue that is attached
107 * Each sleep queue also contains the wait channel it is attached to, the
108 * list of threads blocked on that wait channel, flags specific to the
109 * wait channel, and the lock used to synchronize with a wait channel.
110 * The flags are used to catch mismatches between the various consumers
111 * of the sleep queue API (e.g. sleep/wakeup and condition variables).
112 * The lock pointer is only used when invariants are enabled for various
116 * c - sleep queue chain lock
119 TAILQ_HEAD(, thread) sq_blocked[NR_SLEEPQS]; /* (c) Blocked threads. */
120 LIST_ENTRY(sleepqueue) sq_hash; /* (c) Chain and free list. */
121 LIST_HEAD(, sleepqueue) sq_free; /* (c) Free queues. */
122 void *sq_wchan; /* (c) Wait channel. */
124 int sq_type; /* (c) Queue type. */
125 struct lock_object *sq_lock; /* (c) Associated lock. */
129 struct sleepqueue_chain {
130 LIST_HEAD(, sleepqueue) sc_queues; /* List of sleep queues. */
131 struct mtx sc_lock; /* Spin lock for this chain. */
132 #ifdef SLEEPQUEUE_PROFILING
133 u_int sc_depth; /* Length of sc_queues. */
134 u_int sc_max_depth; /* Max length of sc_queues. */
138 #ifdef SLEEPQUEUE_PROFILING
139 u_int sleepq_max_depth;
140 SYSCTL_NODE(_debug, OID_AUTO, sleepq, CTLFLAG_RD, 0, "sleepq profiling");
141 SYSCTL_NODE(_debug_sleepq, OID_AUTO, chains, CTLFLAG_RD, 0,
142 "sleepq chain stats");
143 SYSCTL_UINT(_debug_sleepq, OID_AUTO, max_depth, CTLFLAG_RD, &sleepq_max_depth,
144 0, "maxmimum depth achieved of a single chain");
146 static struct sleepqueue_chain sleepq_chains[SC_TABLESIZE];
147 static uma_zone_t sleepq_zone;
150 * Prototypes for non-exported routines.
152 static int sleepq_catch_signals(void *wchan);
153 static int sleepq_check_signals(void);
154 static int sleepq_check_timeout(void);
156 static void sleepq_dtor(void *mem, int size, void *arg);
158 static int sleepq_init(void *mem, int size, int flags);
159 static void sleepq_resume_thread(struct sleepqueue *sq, struct thread *td,
161 static void sleepq_switch(void *wchan);
162 static void sleepq_timeout(void *arg);
165 * Early initialization of sleep queues that is called from the sleepinit()
169 init_sleepqueues(void)
171 #ifdef SLEEPQUEUE_PROFILING
172 struct sysctl_oid *chain_oid;
177 for (i = 0; i < SC_TABLESIZE; i++) {
178 LIST_INIT(&sleepq_chains[i].sc_queues);
179 mtx_init(&sleepq_chains[i].sc_lock, "sleepq chain", NULL,
181 #ifdef SLEEPQUEUE_PROFILING
182 snprintf(chain_name, sizeof(chain_name), "%d", i);
183 chain_oid = SYSCTL_ADD_NODE(NULL,
184 SYSCTL_STATIC_CHILDREN(_debug_sleepq_chains), OID_AUTO,
185 chain_name, CTLFLAG_RD, NULL, "sleepq chain stats");
186 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO,
187 "depth", CTLFLAG_RD, &sleepq_chains[i].sc_depth, 0, NULL);
188 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO,
189 "max_depth", CTLFLAG_RD, &sleepq_chains[i].sc_max_depth, 0,
193 sleepq_zone = uma_zcreate("SLEEPQUEUE", sizeof(struct sleepqueue),
195 NULL, sleepq_dtor, sleepq_init, NULL, UMA_ALIGN_CACHE, 0);
197 NULL, NULL, sleepq_init, NULL, UMA_ALIGN_CACHE, 0);
200 thread0.td_sleepqueue = sleepq_alloc();
204 * Get a sleep queue for a new thread.
210 return (uma_zalloc(sleepq_zone, M_WAITOK));
214 * Free a sleep queue when a thread is destroyed.
217 sleepq_free(struct sleepqueue *sq)
220 uma_zfree(sleepq_zone, sq);
224 * Lock the sleep queue chain associated with the specified wait channel.
227 sleepq_lock(void *wchan)
229 struct sleepqueue_chain *sc;
231 sc = SC_LOOKUP(wchan);
232 mtx_lock_spin(&sc->sc_lock);
236 * Look up the sleep queue associated with a given wait channel in the hash
237 * table locking the associated sleep queue chain. If no queue is found in
238 * the table, NULL is returned.
241 sleepq_lookup(void *wchan)
243 struct sleepqueue_chain *sc;
244 struct sleepqueue *sq;
246 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__));
247 sc = SC_LOOKUP(wchan);
248 mtx_assert(&sc->sc_lock, MA_OWNED);
249 LIST_FOREACH(sq, &sc->sc_queues, sq_hash)
250 if (sq->sq_wchan == wchan)
256 * Unlock the sleep queue chain associated with a given wait channel.
259 sleepq_release(void *wchan)
261 struct sleepqueue_chain *sc;
263 sc = SC_LOOKUP(wchan);
264 mtx_unlock_spin(&sc->sc_lock);
268 * Places the current thread on the sleep queue for the specified wait
269 * channel. If INVARIANTS is enabled, then it associates the passed in
270 * lock with the sleepq to make sure it is held when that sleep queue is
274 sleepq_add(void *wchan, struct lock_object *lock, const char *wmesg, int flags,
277 struct sleepqueue_chain *sc;
278 struct sleepqueue *sq;
282 sc = SC_LOOKUP(wchan);
283 mtx_assert(&sc->sc_lock, MA_OWNED);
284 MPASS(td->td_sleepqueue != NULL);
285 MPASS(wchan != NULL);
286 MPASS((queue >= 0) && (queue < NR_SLEEPQS));
288 /* If this thread is not allowed to sleep, die a horrible death. */
289 KASSERT(!(td->td_pflags & TDP_NOSLEEPING),
290 ("Trying sleep, but thread marked as sleeping prohibited"));
292 /* Look up the sleep queue associated with the wait channel 'wchan'. */
293 sq = sleepq_lookup(wchan);
296 * If the wait channel does not already have a sleep queue, use
297 * this thread's sleep queue. Otherwise, insert the current thread
298 * into the sleep queue already in use by this wait channel.
304 sq = td->td_sleepqueue;
305 for (i = 0; i < NR_SLEEPQS; i++)
306 KASSERT(TAILQ_EMPTY(&sq->sq_blocked[i]),
307 ("thread's sleep queue %d is not empty", i));
308 KASSERT(LIST_EMPTY(&sq->sq_free),
309 ("thread's sleep queue has a non-empty free list"));
310 KASSERT(sq->sq_wchan == NULL, ("stale sq_wchan pointer"));
312 sq->sq_type = flags & SLEEPQ_TYPE;
314 #ifdef SLEEPQUEUE_PROFILING
316 if (sc->sc_depth > sc->sc_max_depth) {
317 sc->sc_max_depth = sc->sc_depth;
318 if (sc->sc_max_depth > sleepq_max_depth)
319 sleepq_max_depth = sc->sc_max_depth;
322 sq = td->td_sleepqueue;
323 LIST_INSERT_HEAD(&sc->sc_queues, sq, sq_hash);
324 sq->sq_wchan = wchan;
326 MPASS(wchan == sq->sq_wchan);
327 MPASS(lock == sq->sq_lock);
328 MPASS((flags & SLEEPQ_TYPE) == sq->sq_type);
329 LIST_INSERT_HEAD(&sq->sq_free, td->td_sleepqueue, sq_hash);
332 TAILQ_INSERT_TAIL(&sq->sq_blocked[queue], td, td_slpq);
333 td->td_sleepqueue = NULL;
334 td->td_sqqueue = queue;
335 td->td_wchan = wchan;
336 td->td_wmesg = wmesg;
337 if (flags & SLEEPQ_INTERRUPTIBLE) {
338 td->td_flags |= TDF_SINTR;
339 td->td_flags &= ~TDF_SLEEPABORT;
345 * Sets a timeout that will remove the current thread from the specified
346 * sleep queue after timo ticks if the thread has not already been awakened.
349 sleepq_set_timeout(void *wchan, int timo)
351 struct sleepqueue_chain *sc;
355 sc = SC_LOOKUP(wchan);
356 mtx_assert(&sc->sc_lock, MA_OWNED);
357 MPASS(TD_ON_SLEEPQ(td));
358 MPASS(td->td_sleepqueue == NULL);
359 MPASS(wchan != NULL);
360 callout_reset(&td->td_slpcallout, timo, sleepq_timeout, td);
364 * Marks the pending sleep of the current thread as interruptible and
365 * makes an initial check for pending signals before putting a thread
366 * to sleep. Enters and exits with the thread lock held. Thread lock
367 * may have transitioned from the sleepq lock to a run lock.
370 sleepq_catch_signals(void *wchan)
372 struct sleepqueue_chain *sc;
373 struct sleepqueue *sq;
381 sc = SC_LOOKUP(wchan);
382 mtx_assert(&sc->sc_lock, MA_OWNED);
383 MPASS(wchan != NULL);
384 CTR3(KTR_PROC, "sleepq catching signals: thread %p (pid %ld, %s)",
385 (void *)td, (long)p->p_pid, td->td_name);
387 mtx_unlock_spin(&sc->sc_lock);
389 /* See if there are any pending signals for this thread. */
392 mtx_lock(&ps->ps_mtx);
395 mtx_unlock(&ps->ps_mtx);
396 ret = thread_suspend_check(1);
397 MPASS(ret == 0 || ret == EINTR || ret == ERESTART);
399 if (SIGISMEMBER(ps->ps_sigintr, sig))
403 mtx_unlock(&ps->ps_mtx);
406 * Lock sleepq chain before unlocking proc
407 * without this, we could lose a race.
409 mtx_lock_spin(&sc->sc_lock);
413 if (!(td->td_flags & TDF_INTERRUPT)) {
414 sleepq_switch(wchan);
417 /* KSE threads tried unblocking us. */
418 ret = td->td_intrval;
419 MPASS(ret == EINTR || ret == ERESTART || ret == EWOULDBLOCK);
422 * There were pending signals and this thread is still
423 * on the sleep queue, remove it from the sleep queue.
425 if (TD_ON_SLEEPQ(td)) {
426 sq = sleepq_lookup(wchan);
427 sleepq_resume_thread(sq, td, -1);
429 mtx_unlock_spin(&sc->sc_lock);
430 MPASS(td->td_lock != &sc->sc_lock);
435 * Switches to another thread if we are still asleep on a sleep queue.
436 * Returns with thread lock.
439 sleepq_switch(void *wchan)
441 struct sleepqueue_chain *sc;
445 sc = SC_LOOKUP(wchan);
446 mtx_assert(&sc->sc_lock, MA_OWNED);
447 THREAD_LOCK_ASSERT(td, MA_OWNED);
448 /* We were removed */
449 if (td->td_sleepqueue != NULL) {
450 mtx_unlock_spin(&sc->sc_lock);
453 thread_lock_set(td, &sc->sc_lock);
455 MPASS(td->td_sleepqueue == NULL);
458 SCHED_STAT_INC(switch_sleepq);
459 mi_switch(SW_VOL, NULL);
460 KASSERT(TD_IS_RUNNING(td), ("running but not TDS_RUNNING"));
461 CTR3(KTR_PROC, "sleepq resume: thread %p (pid %ld, %s)",
462 (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name);
466 * Check to see if we timed out.
469 sleepq_check_timeout(void)
474 THREAD_LOCK_ASSERT(td, MA_OWNED);
477 * If TDF_TIMEOUT is set, we timed out.
479 if (td->td_flags & TDF_TIMEOUT) {
480 td->td_flags &= ~TDF_TIMEOUT;
481 return (EWOULDBLOCK);
485 * If TDF_TIMOFAIL is set, the timeout ran after we had
486 * already been woken up.
488 if (td->td_flags & TDF_TIMOFAIL)
489 td->td_flags &= ~TDF_TIMOFAIL;
492 * If callout_stop() fails, then the timeout is running on
493 * another CPU, so synchronize with it to avoid having it
494 * accidentally wake up a subsequent sleep.
496 else if (callout_stop(&td->td_slpcallout) == 0) {
497 td->td_flags |= TDF_TIMEOUT;
499 SCHED_STAT_INC(switch_sleepqtimo);
500 mi_switch(SW_INVOL, NULL);
506 * Check to see if we were awoken by a signal.
509 sleepq_check_signals(void)
514 THREAD_LOCK_ASSERT(td, MA_OWNED);
516 /* We are no longer in an interruptible sleep. */
517 if (td->td_flags & TDF_SINTR)
518 td->td_flags &= ~TDF_SINTR;
520 if (td->td_flags & TDF_SLEEPABORT) {
521 td->td_flags &= ~TDF_SLEEPABORT;
522 return (td->td_intrval);
525 if (td->td_flags & TDF_INTERRUPT)
526 return (td->td_intrval);
532 * Block the current thread until it is awakened from its sleep queue.
535 sleepq_wait(void *wchan)
540 MPASS(!(td->td_flags & TDF_SINTR));
542 sleepq_switch(wchan);
547 * Block the current thread until it is awakened from its sleep queue
548 * or it is interrupted by a signal.
551 sleepq_wait_sig(void *wchan)
556 rcatch = sleepq_catch_signals(wchan);
557 rval = sleepq_check_signals();
558 thread_unlock(curthread);
565 * Block the current thread until it is awakened from its sleep queue
566 * or it times out while waiting.
569 sleepq_timedwait(void *wchan)
575 MPASS(!(td->td_flags & TDF_SINTR));
577 sleepq_switch(wchan);
578 rval = sleepq_check_timeout();
585 * Block the current thread until it is awakened from its sleep queue,
586 * it is interrupted by a signal, or it times out waiting to be awakened.
589 sleepq_timedwait_sig(void *wchan)
591 int rcatch, rvalt, rvals;
593 rcatch = sleepq_catch_signals(wchan);
594 rvalt = sleepq_check_timeout();
595 rvals = sleepq_check_signals();
596 thread_unlock(curthread);
605 * Removes a thread from a sleep queue and makes it
609 sleepq_resume_thread(struct sleepqueue *sq, struct thread *td, int pri)
611 struct sleepqueue_chain *sc;
614 MPASS(sq->sq_wchan != NULL);
615 MPASS(td->td_wchan == sq->sq_wchan);
616 MPASS(td->td_sqqueue < NR_SLEEPQS && td->td_sqqueue >= 0);
617 THREAD_LOCK_ASSERT(td, MA_OWNED);
618 sc = SC_LOOKUP(sq->sq_wchan);
619 mtx_assert(&sc->sc_lock, MA_OWNED);
621 /* Remove the thread from the queue. */
622 TAILQ_REMOVE(&sq->sq_blocked[td->td_sqqueue], td, td_slpq);
625 * Get a sleep queue for this thread. If this is the last waiter,
626 * use the queue itself and take it out of the chain, otherwise,
627 * remove a queue from the free list.
629 if (LIST_EMPTY(&sq->sq_free)) {
630 td->td_sleepqueue = sq;
634 #ifdef SLEEPQUEUE_PROFILING
638 td->td_sleepqueue = LIST_FIRST(&sq->sq_free);
639 LIST_REMOVE(td->td_sleepqueue, sq_hash);
643 td->td_flags &= ~TDF_SINTR;
646 * Note that thread td might not be sleeping if it is running
647 * sleepq_catch_signals() on another CPU or is blocked on
648 * its proc lock to check signals. It doesn't hurt to clear
649 * the sleeping flag if it isn't set though, so we just always
650 * do it. However, we can't assert that it is set.
652 CTR3(KTR_PROC, "sleepq_wakeup: thread %p (pid %ld, %s)",
653 (void *)td, (long)td->td_proc->p_pid, td->td_name);
656 /* Adjust priority if requested. */
657 MPASS(pri == -1 || (pri >= PRI_MIN && pri <= PRI_MAX));
658 if (pri != -1 && td->td_priority > pri)
665 * UMA zone item deallocator.
668 sleepq_dtor(void *mem, int size, void *arg)
670 struct sleepqueue *sq;
674 for (i = 0; i < NR_SLEEPQS; i++)
675 MPASS(TAILQ_EMPTY(&sq->sq_blocked[i]));
680 * UMA zone item initializer.
683 sleepq_init(void *mem, int size, int flags)
685 struct sleepqueue *sq;
690 for (i = 0; i < NR_SLEEPQS; i++)
691 TAILQ_INIT(&sq->sq_blocked[i]);
692 LIST_INIT(&sq->sq_free);
697 * Find the highest priority thread sleeping on a wait channel and resume it.
700 sleepq_signal(void *wchan, int flags, int pri, int queue)
702 struct sleepqueue *sq;
703 struct thread *td, *besttd;
705 CTR2(KTR_PROC, "sleepq_signal(%p, %d)", wchan, flags);
706 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__));
707 MPASS((queue >= 0) && (queue < NR_SLEEPQS));
708 sq = sleepq_lookup(wchan);
711 KASSERT(sq->sq_type == (flags & SLEEPQ_TYPE),
712 ("%s: mismatch between sleep/wakeup and cv_*", __func__));
715 * Find the highest priority thread on the queue. If there is a
716 * tie, use the thread that first appears in the queue as it has
717 * been sleeping the longest since threads are always added to
718 * the tail of sleep queues.
721 TAILQ_FOREACH(td, &sq->sq_blocked[queue], td_slpq) {
722 if (besttd == NULL || td->td_priority < besttd->td_priority)
725 MPASS(besttd != NULL);
727 sleepq_resume_thread(sq, besttd, pri);
728 thread_unlock(besttd);
732 * Resume all threads sleeping on a specified wait channel.
735 sleepq_broadcast(void *wchan, int flags, int pri, int queue)
737 struct sleepqueue *sq;
740 CTR2(KTR_PROC, "sleepq_broadcast(%p, %d)", wchan, flags);
741 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__));
742 MPASS((queue >= 0) && (queue < NR_SLEEPQS));
743 sq = sleepq_lookup(wchan);
745 sleepq_release(wchan);
748 KASSERT(sq->sq_type == (flags & SLEEPQ_TYPE),
749 ("%s: mismatch between sleep/wakeup and cv_*", __func__));
751 /* Resume all blocked threads on the sleep queue. */
752 while (!TAILQ_EMPTY(&sq->sq_blocked[queue])) {
753 td = TAILQ_FIRST(&sq->sq_blocked[queue]);
755 sleepq_resume_thread(sq, td, pri);
758 sleepq_release(wchan);
762 * Time sleeping threads out. When the timeout expires, the thread is
763 * removed from the sleep queue and made runnable if it is still asleep.
766 sleepq_timeout(void *arg)
768 struct sleepqueue_chain *sc;
769 struct sleepqueue *sq;
774 CTR3(KTR_PROC, "sleepq_timeout: thread %p (pid %ld, %s)",
775 (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name);
778 * First, see if the thread is asleep and get the wait channel if
782 if (TD_IS_SLEEPING(td) && TD_ON_SLEEPQ(td)) {
783 wchan = td->td_wchan;
784 sc = SC_LOOKUP(wchan);
785 MPASS(td->td_lock == &sc->sc_lock);
786 sq = sleepq_lookup(wchan);
788 td->td_flags |= TDF_TIMEOUT;
789 sleepq_resume_thread(sq, td, -1);
794 * If the thread is on the SLEEPQ but not sleeping and we have it
795 * locked it must be in sleepq_catch_signals(). Let it know we've
796 * timedout here so it can remove itself.
798 if (TD_ON_SLEEPQ(td)) {
799 td->td_flags |= TDF_TIMEOUT | TDF_INTERRUPT;
800 td->td_intrval = EWOULDBLOCK;
806 * Now check for the edge cases. First, if TDF_TIMEOUT is set,
807 * then the other thread has already yielded to us, so clear
808 * the flag and resume it. If TDF_TIMEOUT is not set, then the
809 * we know that the other thread is not on a sleep queue, but it
810 * hasn't resumed execution yet. In that case, set TDF_TIMOFAIL
811 * to let it know that the timeout has already run and doesn't
812 * need to be canceled.
814 if (td->td_flags & TDF_TIMEOUT) {
815 MPASS(TD_IS_SLEEPING(td));
816 td->td_flags &= ~TDF_TIMEOUT;
820 td->td_flags |= TDF_TIMOFAIL;
825 * Resumes a specific thread from the sleep queue associated with a specific
826 * wait channel if it is on that queue.
829 sleepq_remove(struct thread *td, void *wchan)
831 struct sleepqueue *sq;
834 * Look up the sleep queue for this wait channel, then re-check
835 * that the thread is asleep on that channel, if it is not, then
838 MPASS(wchan != NULL);
840 sq = sleepq_lookup(wchan);
842 * We can not lock the thread here as it may be sleeping on a
843 * different sleepq. However, holding the sleepq lock for this
844 * wchan can guarantee that we do not miss a wakeup for this
845 * channel. The asserts below will catch any false positives.
847 if (!TD_ON_SLEEPQ(td) || td->td_wchan != wchan) {
848 sleepq_release(wchan);
851 /* Thread is asleep on sleep queue sq, so wake it up. */
854 MPASS(td->td_wchan == wchan);
855 sleepq_resume_thread(sq, td, -1);
857 sleepq_release(wchan);
861 * Abort a thread as if an interrupt had occurred. Only abort
862 * interruptible waits (unfortunately it isn't safe to abort others).
865 sleepq_abort(struct thread *td, int intrval)
867 struct sleepqueue *sq;
870 THREAD_LOCK_ASSERT(td, MA_OWNED);
871 MPASS(TD_ON_SLEEPQ(td));
872 MPASS(td->td_flags & TDF_SINTR);
873 MPASS(intrval == EINTR || intrval == ERESTART);
876 * If the TDF_TIMEOUT flag is set, just leave. A
877 * timeout is scheduled anyhow.
879 if (td->td_flags & TDF_TIMEOUT)
882 CTR3(KTR_PROC, "sleepq_abort: thread %p (pid %ld, %s)",
883 (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name);
884 td->td_intrval = intrval;
885 td->td_flags |= TDF_SLEEPABORT;
887 * If the thread has not slept yet it will find the signal in
888 * sleepq_catch_signals() and call sleepq_resume_thread. Otherwise
889 * we have to do it here.
891 if (!TD_IS_SLEEPING(td))
893 wchan = td->td_wchan;
894 MPASS(wchan != NULL);
895 sq = sleepq_lookup(wchan);
898 /* Thread is asleep on sleep queue sq, so wake it up. */
899 sleepq_resume_thread(sq, td, -1);
903 DB_SHOW_COMMAND(sleepq, db_show_sleepqueue)
905 struct sleepqueue_chain *sc;
906 struct sleepqueue *sq;
908 struct lock_object *lock;
918 * First, see if there is an active sleep queue for the wait channel
919 * indicated by the address.
921 wchan = (void *)addr;
922 sc = SC_LOOKUP(wchan);
923 LIST_FOREACH(sq, &sc->sc_queues, sq_hash)
924 if (sq->sq_wchan == wchan)
928 * Second, see if there is an active sleep queue at the address
931 for (i = 0; i < SC_TABLESIZE; i++)
932 LIST_FOREACH(sq, &sleepq_chains[i].sc_queues, sq_hash) {
933 if (sq == (struct sleepqueue *)addr)
937 db_printf("Unable to locate a sleep queue via %p\n", (void *)addr);
940 db_printf("Wait channel: %p\n", sq->sq_wchan);
942 db_printf("Queue type: %d\n", sq->sq_type);
945 db_printf("Associated Interlock: %p - (%s) %s\n", lock,
946 LOCK_CLASS(lock)->lc_name, lock->lo_name);
949 db_printf("Blocked threads:\n");
950 for (i = 0; i < NR_SLEEPQS; i++) {
951 db_printf("\nQueue[%d]:\n", i);
952 if (TAILQ_EMPTY(&sq->sq_blocked[i]))
953 db_printf("\tempty\n");
955 TAILQ_FOREACH(td, &sq->sq_blocked[0],
957 db_printf("\t%p (tid %d, pid %d, \"%s\")\n", td,
958 td->td_tid, td->td_proc->p_pid,
959 td->td_name[i] != '\0' ? td->td_name :
965 /* Alias 'show sleepqueue' to 'show sleepq'. */
966 DB_SET(sleepqueue, db_show_sleepqueue, db_show_cmd_set, 0, NULL);