2 * Copyright (c) 2000 Jake Burkholder <jake@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.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
30 #include "opt_ktrace.h"
32 #include <sys/param.h>
33 #include <sys/systm.h>
35 #include <sys/mutex.h>
37 #include <sys/kernel.h>
39 #include <sys/condvar.h>
40 #include <sys/sched.h>
41 #include <sys/signalvar.h>
42 #include <sys/sleepqueue.h>
43 #include <sys/resourcevar.h>
46 #include <sys/ktrace.h>
50 * Common sanity checks for cv_wait* functions.
52 #define CV_ASSERT(cvp, lock, td) do { \
53 KASSERT((td) != NULL, ("%s: curthread NULL", __func__)); \
54 KASSERT(TD_IS_RUNNING(td), ("%s: not TDS_RUNNING", __func__)); \
55 KASSERT((cvp) != NULL, ("%s: cvp NULL", __func__)); \
56 KASSERT((lock) != NULL, ("%s: lock NULL", __func__)); \
60 * Initialize a condition variable. Must be called before use.
63 cv_init(struct cv *cvp, const char *desc)
66 cvp->cv_description = desc;
71 * Destroy a condition variable. The condition variable must be re-initialized
72 * in order to be re-used.
75 cv_destroy(struct cv *cvp)
78 struct sleepqueue *sq;
81 sq = sleepq_lookup(cvp);
83 KASSERT(sq == NULL, ("%s: associated sleep queue non-empty", __func__));
88 * Wait on a condition variable. The current thread is placed on the condition
89 * variable's wait queue and suspended. A cv_signal or cv_broadcast on the same
90 * condition variable will resume the thread. The mutex is released before
91 * sleeping and will be held on return. It is recommended that the mutex be
92 * held when cv_signal or cv_broadcast are called.
95 _cv_wait(struct cv *cvp, struct lock_object *lock)
97 WITNESS_SAVE_DECL(lock_witness);
98 struct lock_class *class;
104 if (KTRPOINT(td, KTR_CSW))
107 CV_ASSERT(cvp, lock, td);
108 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
109 "Waiting on \"%s\"", cvp->cv_description);
110 WITNESS_SAVE(lock, lock_witness);
111 class = LOCK_CLASS(lock);
113 if (cold || panicstr) {
115 * During autoconfiguration, just give interrupts
116 * a chance, then just return. Don't run any other
117 * thread or panic below, in case this is the idle
118 * process and already asleep.
128 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
129 if (class->lc_flags & LC_SLEEPABLE)
131 lock_state = class->lc_unlock(lock);
132 if (class->lc_flags & LC_SLEEPABLE)
137 if (KTRPOINT(td, KTR_CSW))
141 class->lc_lock(lock, lock_state);
142 WITNESS_RESTORE(lock, lock_witness);
146 * Wait on a condition variable. This function differs from cv_wait by
147 * not aquiring the mutex after condition variable was signaled.
150 _cv_wait_unlock(struct cv *cvp, struct lock_object *lock)
152 struct lock_class *class;
157 if (KTRPOINT(td, KTR_CSW))
160 CV_ASSERT(cvp, lock, td);
161 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
162 "Waiting on \"%s\"", cvp->cv_description);
163 class = LOCK_CLASS(lock);
165 if (cold || panicstr) {
167 * During autoconfiguration, just give interrupts
168 * a chance, then just return. Don't run any other
169 * thread or panic below, in case this is the idle
170 * process and already asleep.
172 class->lc_unlock(lock);
181 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
182 if (class->lc_flags & LC_SLEEPABLE)
184 class->lc_unlock(lock);
185 if (class->lc_flags & LC_SLEEPABLE)
190 if (KTRPOINT(td, KTR_CSW))
197 * Wait on a condition variable, allowing interruption by signals. Return 0 if
198 * the thread was resumed with cv_signal or cv_broadcast, EINTR or ERESTART if
199 * a signal was caught. If ERESTART is returned the system call should be
200 * restarted if possible.
203 _cv_wait_sig(struct cv *cvp, struct lock_object *lock)
205 WITNESS_SAVE_DECL(lock_witness);
206 struct lock_class *class;
209 int lock_state, rval;
214 if (KTRPOINT(td, KTR_CSW))
217 CV_ASSERT(cvp, lock, td);
218 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
219 "Waiting on \"%s\"", cvp->cv_description);
220 WITNESS_SAVE(lock, lock_witness);
221 class = LOCK_CLASS(lock);
223 if (cold || panicstr) {
225 * After a panic, or during autoconfiguration, just give
226 * interrupts a chance, then just return; don't run any other
227 * procs or panic below, in case this is the idle process and
238 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR |
239 SLEEPQ_INTERRUPTIBLE, 0);
240 if (class->lc_flags & LC_SLEEPABLE)
242 lock_state = class->lc_unlock(lock);
243 if (class->lc_flags & LC_SLEEPABLE)
245 rval = sleepq_wait_sig(cvp, 0);
248 if (KTRPOINT(td, KTR_CSW))
252 class->lc_lock(lock, lock_state);
253 WITNESS_RESTORE(lock, lock_witness);
259 * Wait on a condition variable for at most timo/hz seconds. Returns 0 if the
260 * process was resumed by cv_signal or cv_broadcast, EWOULDBLOCK if the timeout
264 _cv_timedwait(struct cv *cvp, struct lock_object *lock, int timo)
266 WITNESS_SAVE_DECL(lock_witness);
267 struct lock_class *class;
269 int lock_state, rval;
274 if (KTRPOINT(td, KTR_CSW))
277 CV_ASSERT(cvp, lock, td);
278 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
279 "Waiting on \"%s\"", cvp->cv_description);
280 WITNESS_SAVE(lock, lock_witness);
281 class = LOCK_CLASS(lock);
283 if (cold || panicstr) {
285 * After a panic, or during autoconfiguration, just give
286 * interrupts a chance, then just return; don't run any other
287 * thread or panic below, in case this is the idle process and
298 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
299 sleepq_set_timeout(cvp, timo);
300 if (class->lc_flags & LC_SLEEPABLE)
302 lock_state = class->lc_unlock(lock);
303 if (class->lc_flags & LC_SLEEPABLE)
305 rval = sleepq_timedwait(cvp, 0);
308 if (KTRPOINT(td, KTR_CSW))
312 class->lc_lock(lock, lock_state);
313 WITNESS_RESTORE(lock, lock_witness);
319 * Wait on a condition variable for at most timo/hz seconds, allowing
320 * interruption by signals. Returns 0 if the thread was resumed by cv_signal
321 * or cv_broadcast, EWOULDBLOCK if the timeout expires, and EINTR or ERESTART if
322 * a signal was caught.
325 _cv_timedwait_sig(struct cv *cvp, struct lock_object *lock, int timo)
327 WITNESS_SAVE_DECL(lock_witness);
328 struct lock_class *class;
331 int lock_state, rval;
337 if (KTRPOINT(td, KTR_CSW))
340 CV_ASSERT(cvp, lock, td);
341 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
342 "Waiting on \"%s\"", cvp->cv_description);
343 WITNESS_SAVE(lock, lock_witness);
344 class = LOCK_CLASS(lock);
346 if (cold || panicstr) {
348 * After a panic, or during autoconfiguration, just give
349 * interrupts a chance, then just return; don't run any other
350 * thread or panic below, in case this is the idle process and
361 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR |
362 SLEEPQ_INTERRUPTIBLE, 0);
363 sleepq_set_timeout(cvp, timo);
364 if (class->lc_flags & LC_SLEEPABLE)
366 lock_state = class->lc_unlock(lock);
367 if (class->lc_flags & LC_SLEEPABLE)
369 rval = sleepq_timedwait_sig(cvp, 0);
372 if (KTRPOINT(td, KTR_CSW))
376 class->lc_lock(lock, lock_state);
377 WITNESS_RESTORE(lock, lock_witness);
383 * Signal a condition variable, wakes up one waiting thread. Will also wakeup
384 * the swapper if the process is not in memory, so that it can bring the
385 * sleeping process in. Note that this may also result in additional threads
386 * being made runnable. Should be called with the same mutex as was passed to
390 cv_signal(struct cv *cvp)
394 if (cvp->cv_waiters > 0) {
396 sleepq_signal(cvp, SLEEPQ_CONDVAR, 0, 0);
402 * Broadcast a signal to a condition variable. Wakes up all waiting threads.
403 * Should be called with the same mutex as was passed to cv_wait held.
406 cv_broadcastpri(struct cv *cvp, int pri)
409 * XXX sleepq_broadcast pri argument changed from -1 meaning
410 * no pri to 0 meaning no pri.
415 if (cvp->cv_waiters > 0) {
417 sleepq_broadcast(cvp, SLEEPQ_CONDVAR, pri, 0);