2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2005 David Xu <davidxu@freebsd.org>
5 * Copyright (c) 2015 The FreeBSD Foundation
8 * Portions of this software were developed by Konstantin Belousov
9 * under sponsorship from the FreeBSD Foundation.
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
14 * 1. Redistributions of source code must retain the above copyright
15 * notice unmodified, this list of conditions, and the following
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
36 #include "namespace.h"
42 #include "un-namespace.h"
44 #include "thr_private.h"
46 _Static_assert(sizeof(struct pthread_cond) <= THR_PAGE_SIZE_MIN,
47 "pthread_cond too large");
52 int __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
53 const struct timespec * abstime);
54 static int cond_init(pthread_cond_t *cond, const pthread_condattr_t *attr);
55 static int cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex,
56 const struct timespec *abstime, int cancel);
57 static int cond_signal_common(pthread_cond_t *cond);
58 static int cond_broadcast_common(pthread_cond_t *cond);
61 * Double underscore versions are cancellation points. Single underscore
62 * versions are not and are provided for libc internal usage (which
63 * shouldn't introduce cancellation points).
65 __weak_reference(__thr_cond_wait, pthread_cond_wait);
66 __weak_reference(__thr_cond_wait, __pthread_cond_wait);
67 __weak_reference(_thr_cond_wait, _pthread_cond_wait);
68 __weak_reference(__pthread_cond_timedwait, pthread_cond_timedwait);
69 __weak_reference(_thr_cond_init, pthread_cond_init);
70 __weak_reference(_thr_cond_init, _pthread_cond_init);
71 __weak_reference(_thr_cond_destroy, pthread_cond_destroy);
72 __weak_reference(_thr_cond_destroy, _pthread_cond_destroy);
73 __weak_reference(_thr_cond_signal, pthread_cond_signal);
74 __weak_reference(_thr_cond_signal, _pthread_cond_signal);
75 __weak_reference(_thr_cond_broadcast, pthread_cond_broadcast);
76 __weak_reference(_thr_cond_broadcast, _pthread_cond_broadcast);
78 #define CV_PSHARED(cvp) (((cvp)->kcond.c_flags & USYNC_PROCESS_SHARED) != 0)
81 cond_init_body(struct pthread_cond *cvp, const struct pthread_cond_attr *cattr)
85 cvp->kcond.c_clockid = CLOCK_REALTIME;
88 cvp->kcond.c_flags |= USYNC_PROCESS_SHARED;
89 cvp->kcond.c_clockid = cattr->c_clockid;
94 cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr)
96 struct pthread_cond *cvp;
97 const struct pthread_cond_attr *cattr;
100 cattr = cond_attr != NULL ? *cond_attr : NULL;
101 if (cattr == NULL || cattr->c_pshared == PTHREAD_PROCESS_PRIVATE) {
103 cvp = calloc(1, sizeof(struct pthread_cond));
108 cvp = __thr_pshared_offpage(cond, 1);
114 * Initialise the condition variable structure:
116 cond_init_body(cvp, cattr);
117 *cond = pshared ? THR_PSHARED_PTR : cvp;
122 init_static(struct pthread *thread, pthread_cond_t *cond)
126 THR_LOCK_ACQUIRE(thread, &_cond_static_lock);
129 ret = cond_init(cond, NULL);
133 THR_LOCK_RELEASE(thread, &_cond_static_lock);
138 #define CHECK_AND_INIT_COND \
139 if (*cond == THR_PSHARED_PTR) { \
140 cvp = __thr_pshared_offpage(cond, 0); \
143 } else if (__predict_false((cvp = (*cond)) <= THR_COND_DESTROYED)) { \
144 if (cvp == THR_COND_INITIALIZER) { \
146 ret = init_static(_get_curthread(), cond); \
149 } else if (cvp == THR_COND_DESTROYED) { \
156 _thr_cond_init(pthread_cond_t * __restrict cond,
157 const pthread_condattr_t * __restrict cond_attr)
161 return (cond_init(cond, cond_attr));
165 _thr_cond_destroy(pthread_cond_t *cond)
167 struct pthread_cond *cvp;
171 if (*cond == THR_PSHARED_PTR) {
172 cvp = __thr_pshared_offpage(cond, 0);
174 if (cvp->kcond.c_has_waiters)
177 __thr_pshared_destroy(cond);
180 *cond = THR_COND_DESTROYED;
181 } else if ((cvp = *cond) == THR_COND_INITIALIZER) {
183 } else if (cvp == THR_COND_DESTROYED) {
187 if (cvp->__has_user_waiters || cvp->kcond.c_has_waiters)
190 *cond = THR_COND_DESTROYED;
198 * Cancellation behavior:
199 * Thread may be canceled at start, if thread is canceled, it means it
200 * did not get a wakeup from pthread_cond_signal(), otherwise, it is
202 * Thread cancellation never cause wakeup from pthread_cond_signal()
206 cond_wait_kernel(struct pthread_cond *cvp, struct pthread_mutex *mp,
207 const struct timespec *abstime, int cancel)
209 struct pthread *curthread;
210 int error, error2, recurse, robust;
212 curthread = _get_curthread();
213 robust = _mutex_enter_robust(curthread, mp);
215 error = _mutex_cv_detach(mp, &recurse);
218 _mutex_leave_robust(curthread, mp);
223 _thr_cancel_enter2(curthread, 0);
224 error = _thr_ucond_wait(&cvp->kcond, &mp->m_lock, abstime,
225 CVWAIT_ABSTIME | CVWAIT_CLOCKID);
227 _thr_cancel_leave(curthread, 0);
230 * Note that PP mutex and ROBUST mutex may return
231 * interesting error codes.
234 error2 = _mutex_cv_lock(mp, recurse, true);
235 } else if (error == EINTR || error == ETIMEDOUT) {
236 error2 = _mutex_cv_lock(mp, recurse, true);
238 * Do not do cancellation on EOWNERDEAD there. The
239 * cancellation cleanup handler will use the protected
240 * state and unlock the mutex without making the state
241 * consistent and the state will be unrecoverable.
243 if (error2 == 0 && cancel) {
245 _mutex_leave_robust(curthread, mp);
248 _thr_testcancel(curthread);
254 /* We know that it didn't unlock the mutex. */
255 _mutex_cv_attach(mp, recurse);
258 _mutex_leave_robust(curthread, mp);
261 _thr_testcancel(curthread);
266 _mutex_leave_robust(curthread, mp);
267 return (error2 != 0 ? error2 : error);
271 * Thread waits in userland queue whenever possible, when thread
272 * is signaled or broadcasted, it is removed from the queue, and
273 * is saved in curthread's defer_waiters[] buffer, but won't be
274 * woken up until mutex is unlocked.
278 cond_wait_user(struct pthread_cond *cvp, struct pthread_mutex *mp,
279 const struct timespec *abstime, int cancel)
281 struct pthread *curthread;
282 struct sleepqueue *sq;
283 int deferred, error, error2, recurse;
285 curthread = _get_curthread();
286 if (curthread->wchan != NULL)
287 PANIC("thread %p was already on queue.", curthread);
290 _thr_testcancel(curthread);
294 * set __has_user_waiters before unlocking mutex, this allows
295 * us to check it without locking in pthread_cond_signal().
297 cvp->__has_user_waiters = 1;
299 (void)_mutex_cv_unlock(mp, &recurse, &deferred);
300 curthread->mutex_obj = mp;
301 _sleepq_add(cvp, curthread);
303 _thr_clear_wake(curthread);
307 if ((mp->m_lock.m_owner & UMUTEX_CONTESTED) == 0)
308 (void)_umtx_op_err(&mp->m_lock,
309 UMTX_OP_MUTEX_WAKE2, mp->m_lock.m_flags,
312 if (curthread->nwaiter_defer > 0) {
313 _thr_wake_all(curthread->defer_waiters,
314 curthread->nwaiter_defer);
315 curthread->nwaiter_defer = 0;
319 _thr_cancel_enter2(curthread, 0);
320 error = _thr_sleep(curthread, cvp->kcond.c_clockid, abstime);
322 _thr_cancel_leave(curthread, 0);
325 if (curthread->wchan == NULL) {
328 } else if (cancel && SHOULD_CANCEL(curthread)) {
329 sq = _sleepq_lookup(cvp);
330 cvp->__has_user_waiters = _sleepq_remove(sq, curthread);
332 curthread->mutex_obj = NULL;
333 error2 = _mutex_cv_lock(mp, recurse, false);
334 if (!THR_IN_CRITICAL(curthread))
335 _pthread_exit(PTHREAD_CANCELED);
336 else /* this should not happen */
338 } else if (error == ETIMEDOUT) {
339 sq = _sleepq_lookup(cvp);
340 cvp->__has_user_waiters =
341 _sleepq_remove(sq, curthread);
346 curthread->mutex_obj = NULL;
347 error2 = _mutex_cv_lock(mp, recurse, false);
354 cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex,
355 const struct timespec *abstime, int cancel)
357 struct pthread *curthread = _get_curthread();
358 struct pthread_cond *cvp;
359 struct pthread_mutex *mp;
364 if (*mutex == THR_PSHARED_PTR) {
365 mp = __thr_pshared_offpage(mutex, 0);
372 if ((error = _mutex_owned(curthread, mp)) != 0)
375 if (curthread->attr.sched_policy != SCHED_OTHER ||
376 (mp->m_lock.m_flags & (UMUTEX_PRIO_PROTECT | UMUTEX_PRIO_INHERIT |
377 USYNC_PROCESS_SHARED)) != 0 || CV_PSHARED(cvp))
378 return (cond_wait_kernel(cvp, mp, abstime, cancel));
380 return (cond_wait_user(cvp, mp, abstime, cancel));
384 _thr_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
387 return (cond_wait_common(cond, mutex, NULL, 0));
391 __thr_cond_wait(pthread_cond_t * __restrict cond,
392 pthread_mutex_t * __restrict mutex)
395 return (cond_wait_common(cond, mutex, NULL, 1));
399 _thr_cond_timedwait(pthread_cond_t * __restrict cond,
400 pthread_mutex_t * __restrict mutex,
401 const struct timespec * __restrict abstime)
404 if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
405 abstime->tv_nsec >= 1000000000)
408 return (cond_wait_common(cond, mutex, abstime, 0));
412 __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
413 const struct timespec *abstime)
416 if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
417 abstime->tv_nsec >= 1000000000)
420 return (cond_wait_common(cond, mutex, abstime, 1));
424 cond_signal_common(pthread_cond_t *cond)
426 struct pthread *curthread = _get_curthread();
428 struct pthread_cond *cvp;
429 struct pthread_mutex *mp;
430 struct sleepqueue *sq;
435 * If the condition variable is statically initialized, perform dynamic
440 pshared = CV_PSHARED(cvp);
442 _thr_ucond_signal(&cvp->kcond);
444 if (pshared || cvp->__has_user_waiters == 0)
447 curthread = _get_curthread();
450 sq = _sleepq_lookup(cvp);
456 td = _sleepq_first(sq);
458 cvp->__has_user_waiters = _sleepq_remove(sq, td);
459 if (PMUTEX_OWNER_ID(mp) == TID(curthread)) {
460 if (curthread->nwaiter_defer >= MAX_DEFER_WAITERS) {
461 _thr_wake_all(curthread->defer_waiters,
462 curthread->nwaiter_defer);
463 curthread->nwaiter_defer = 0;
465 curthread->defer_waiters[curthread->nwaiter_defer++] =
466 &td->wake_addr->value;
467 mp->m_flags |= PMUTEX_FLAG_DEFERRED;
469 waddr = &td->wake_addr->value;
473 _thr_set_wake(waddr);
477 struct broadcast_arg {
478 struct pthread *curthread;
479 unsigned int *waddrs[MAX_DEFER_WAITERS];
484 drop_cb(struct pthread *td, void *arg)
486 struct broadcast_arg *ba = arg;
487 struct pthread_mutex *mp;
488 struct pthread *curthread = ba->curthread;
491 if (PMUTEX_OWNER_ID(mp) == TID(curthread)) {
492 if (curthread->nwaiter_defer >= MAX_DEFER_WAITERS) {
493 _thr_wake_all(curthread->defer_waiters,
494 curthread->nwaiter_defer);
495 curthread->nwaiter_defer = 0;
497 curthread->defer_waiters[curthread->nwaiter_defer++] =
498 &td->wake_addr->value;
499 mp->m_flags |= PMUTEX_FLAG_DEFERRED;
501 if (ba->count >= MAX_DEFER_WAITERS) {
502 _thr_wake_all(ba->waddrs, ba->count);
505 ba->waddrs[ba->count++] = &td->wake_addr->value;
510 cond_broadcast_common(pthread_cond_t *cond)
513 struct pthread_cond *cvp;
514 struct sleepqueue *sq;
515 struct broadcast_arg ba;
518 * If the condition variable is statically initialized, perform dynamic
523 pshared = CV_PSHARED(cvp);
525 _thr_ucond_broadcast(&cvp->kcond);
527 if (pshared || cvp->__has_user_waiters == 0)
530 ba.curthread = _get_curthread();
534 sq = _sleepq_lookup(cvp);
539 _sleepq_drop(sq, drop_cb, &ba);
540 cvp->__has_user_waiters = 0;
543 _thr_wake_all(ba.waddrs, ba.count);
548 _thr_cond_signal(pthread_cond_t * cond)
551 return (cond_signal_common(cond));
555 _thr_cond_broadcast(pthread_cond_t * cond)
558 return (cond_broadcast_common(cond));