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;
105 if (KTRPOINT(td, KTR_CSW))
106 ktrcsw(1, 0, cv_wmesg(cvp));
108 CV_ASSERT(cvp, lock, td);
109 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
110 "Waiting on \"%s\"", cvp->cv_description);
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.
126 if (lock == &Giant.lock_object)
127 mtx_assert(&Giant, MA_OWNED);
130 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
131 if (lock != &Giant.lock_object) {
132 if (class->lc_flags & LC_SLEEPABLE)
134 WITNESS_SAVE(lock, lock_witness);
135 lock_state = class->lc_unlock(lock);
136 if (class->lc_flags & LC_SLEEPABLE)
142 if (KTRPOINT(td, KTR_CSW))
143 ktrcsw(0, 0, cv_wmesg(cvp));
146 if (lock != &Giant.lock_object) {
147 class->lc_lock(lock, lock_state);
148 WITNESS_RESTORE(lock, lock_witness);
153 * Wait on a condition variable. This function differs from cv_wait by
154 * not aquiring the mutex after condition variable was signaled.
157 _cv_wait_unlock(struct cv *cvp, struct lock_object *lock)
159 struct lock_class *class;
164 if (KTRPOINT(td, KTR_CSW))
165 ktrcsw(1, 0, cv_wmesg(cvp));
167 CV_ASSERT(cvp, lock, td);
168 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
169 "Waiting on \"%s\"", cvp->cv_description);
170 KASSERT(lock != &Giant.lock_object,
171 ("cv_wait_unlock cannot be used with Giant"));
172 class = LOCK_CLASS(lock);
174 if (cold || panicstr) {
176 * During autoconfiguration, just give interrupts
177 * a chance, then just return. Don't run any other
178 * thread or panic below, in case this is the idle
179 * process and already asleep.
181 class->lc_unlock(lock);
190 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
191 if (class->lc_flags & LC_SLEEPABLE)
193 class->lc_unlock(lock);
194 if (class->lc_flags & LC_SLEEPABLE)
199 if (KTRPOINT(td, KTR_CSW))
200 ktrcsw(0, 0, cv_wmesg(cvp));
206 * Wait on a condition variable, allowing interruption by signals. Return 0 if
207 * the thread was resumed with cv_signal or cv_broadcast, EINTR or ERESTART if
208 * a signal was caught. If ERESTART is returned the system call should be
209 * restarted if possible.
212 _cv_wait_sig(struct cv *cvp, struct lock_object *lock)
214 WITNESS_SAVE_DECL(lock_witness);
215 struct lock_class *class;
217 int lock_state, rval;
222 if (KTRPOINT(td, KTR_CSW))
223 ktrcsw(1, 0, cv_wmesg(cvp));
225 CV_ASSERT(cvp, lock, td);
226 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
227 "Waiting on \"%s\"", cvp->cv_description);
228 class = LOCK_CLASS(lock);
230 if (cold || panicstr) {
232 * After a panic, or during autoconfiguration, just give
233 * interrupts a chance, then just return; don't run any other
234 * procs or panic below, in case this is the idle process and
243 if (lock == &Giant.lock_object)
244 mtx_assert(&Giant, MA_OWNED);
247 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR |
248 SLEEPQ_INTERRUPTIBLE, 0);
249 if (lock != &Giant.lock_object) {
250 if (class->lc_flags & LC_SLEEPABLE)
252 WITNESS_SAVE(lock, lock_witness);
253 lock_state = class->lc_unlock(lock);
254 if (class->lc_flags & LC_SLEEPABLE)
257 rval = sleepq_wait_sig(cvp, 0);
260 if (KTRPOINT(td, KTR_CSW))
261 ktrcsw(0, 0, cv_wmesg(cvp));
264 if (lock != &Giant.lock_object) {
265 class->lc_lock(lock, lock_state);
266 WITNESS_RESTORE(lock, lock_witness);
273 * Wait on a condition variable for at most timo/hz seconds. Returns 0 if the
274 * process was resumed by cv_signal or cv_broadcast, EWOULDBLOCK if the timeout
278 _cv_timedwait(struct cv *cvp, struct lock_object *lock, int timo)
280 WITNESS_SAVE_DECL(lock_witness);
281 struct lock_class *class;
283 int lock_state, rval;
288 if (KTRPOINT(td, KTR_CSW))
289 ktrcsw(1, 0, cv_wmesg(cvp));
291 CV_ASSERT(cvp, lock, td);
292 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
293 "Waiting on \"%s\"", cvp->cv_description);
294 class = LOCK_CLASS(lock);
296 if (cold || panicstr) {
298 * After a panic, or during autoconfiguration, just give
299 * interrupts a chance, then just return; don't run any other
300 * thread or panic below, in case this is the idle process and
309 if (lock == &Giant.lock_object)
310 mtx_assert(&Giant, MA_OWNED);
313 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
314 sleepq_set_timeout(cvp, timo);
315 if (lock != &Giant.lock_object) {
316 if (class->lc_flags & LC_SLEEPABLE)
318 WITNESS_SAVE(lock, lock_witness);
319 lock_state = class->lc_unlock(lock);
320 if (class->lc_flags & LC_SLEEPABLE)
323 rval = sleepq_timedwait(cvp, 0);
326 if (KTRPOINT(td, KTR_CSW))
327 ktrcsw(0, 0, cv_wmesg(cvp));
330 if (lock != &Giant.lock_object) {
331 class->lc_lock(lock, lock_state);
332 WITNESS_RESTORE(lock, lock_witness);
339 * Wait on a condition variable for at most timo/hz seconds, allowing
340 * interruption by signals. Returns 0 if the thread was resumed by cv_signal
341 * or cv_broadcast, EWOULDBLOCK if the timeout expires, and EINTR or ERESTART if
342 * a signal was caught.
345 _cv_timedwait_sig(struct cv *cvp, struct lock_object *lock, int timo)
347 WITNESS_SAVE_DECL(lock_witness);
348 struct lock_class *class;
350 int lock_state, rval;
355 if (KTRPOINT(td, KTR_CSW))
356 ktrcsw(1, 0, cv_wmesg(cvp));
358 CV_ASSERT(cvp, lock, td);
359 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
360 "Waiting on \"%s\"", cvp->cv_description);
361 class = LOCK_CLASS(lock);
363 if (cold || panicstr) {
365 * After a panic, or during autoconfiguration, just give
366 * interrupts a chance, then just return; don't run any other
367 * thread or panic below, in case this is the idle process and
376 if (lock == &Giant.lock_object)
377 mtx_assert(&Giant, MA_OWNED);
380 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR |
381 SLEEPQ_INTERRUPTIBLE, 0);
382 sleepq_set_timeout(cvp, timo);
383 if (lock != &Giant.lock_object) {
384 if (class->lc_flags & LC_SLEEPABLE)
386 WITNESS_SAVE(lock, lock_witness);
387 lock_state = class->lc_unlock(lock);
388 if (class->lc_flags & LC_SLEEPABLE)
391 rval = sleepq_timedwait_sig(cvp, 0);
394 if (KTRPOINT(td, KTR_CSW))
395 ktrcsw(0, 0, cv_wmesg(cvp));
398 if (lock != &Giant.lock_object) {
399 class->lc_lock(lock, lock_state);
400 WITNESS_RESTORE(lock, lock_witness);
407 * Signal a condition variable, wakes up one waiting thread. Will also wakeup
408 * the swapper if the process is not in memory, so that it can bring the
409 * sleeping process in. Note that this may also result in additional threads
410 * being made runnable. Should be called with the same mutex as was passed to
414 cv_signal(struct cv *cvp)
420 if (cvp->cv_waiters > 0) {
422 wakeup_swapper = sleepq_signal(cvp, SLEEPQ_CONDVAR, 0, 0);
430 * Broadcast a signal to a condition variable. Wakes up all waiting threads.
431 * Should be called with the same mutex as was passed to cv_wait held.
434 cv_broadcastpri(struct cv *cvp, int pri)
439 * XXX sleepq_broadcast pri argument changed from -1 meaning
440 * no pri to 0 meaning no pri.
446 if (cvp->cv_waiters > 0) {
448 wakeup_swapper = sleepq_broadcast(cvp, SLEEPQ_CONDVAR, pri, 0);