489 lines
12 KiB
C
489 lines
12 KiB
C
/*
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* Copyright (c) 2005 David Xu <davidxu@freebsd.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice unmodified, this list of conditions, and the following
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* disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include "namespace.h"
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#include <stdlib.h>
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#include <errno.h>
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#include <string.h>
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#include <pthread.h>
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#include <limits.h>
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#include "un-namespace.h"
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#include "thr_private.h"
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/*
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* Prototypes
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*/
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int __pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex);
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int __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
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const struct timespec * abstime);
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static int cond_init(pthread_cond_t *cond, const pthread_condattr_t *attr);
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static int cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex,
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const struct timespec *abstime, int cancel);
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static int cond_signal_common(pthread_cond_t *cond);
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static int cond_broadcast_common(pthread_cond_t *cond);
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/*
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* Double underscore versions are cancellation points. Single underscore
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* versions are not and are provided for libc internal usage (which
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* shouldn't introduce cancellation points).
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*/
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__weak_reference(__pthread_cond_wait, pthread_cond_wait);
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__weak_reference(__pthread_cond_timedwait, pthread_cond_timedwait);
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__weak_reference(_pthread_cond_init, pthread_cond_init);
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__weak_reference(_pthread_cond_destroy, pthread_cond_destroy);
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__weak_reference(_pthread_cond_signal, pthread_cond_signal);
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__weak_reference(_pthread_cond_broadcast, pthread_cond_broadcast);
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#define CV_PSHARED(cvp) (((cvp)->__flags & USYNC_PROCESS_SHARED) != 0)
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static int
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cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr)
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{
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struct pthread_cond *cvp;
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int error = 0;
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if ((cvp = (pthread_cond_t)
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calloc(1, sizeof(struct pthread_cond))) == NULL) {
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error = ENOMEM;
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} else {
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/*
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* Initialise the condition variable structure:
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*/
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if (cond_attr == NULL || *cond_attr == NULL) {
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cvp->__clock_id = CLOCK_REALTIME;
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} else {
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if ((*cond_attr)->c_pshared)
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cvp->__flags |= USYNC_PROCESS_SHARED;
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cvp->__clock_id = (*cond_attr)->c_clockid;
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}
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*cond = cvp;
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}
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return (error);
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}
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static int
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init_static(struct pthread *thread, pthread_cond_t *cond)
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{
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int ret;
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THR_LOCK_ACQUIRE(thread, &_cond_static_lock);
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if (*cond == NULL)
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ret = cond_init(cond, NULL);
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else
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ret = 0;
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THR_LOCK_RELEASE(thread, &_cond_static_lock);
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return (ret);
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}
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#define CHECK_AND_INIT_COND \
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if (__predict_false((cvp = (*cond)) <= THR_COND_DESTROYED)) { \
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if (cvp == THR_COND_INITIALIZER) { \
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int ret; \
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ret = init_static(_get_curthread(), cond); \
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if (ret) \
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return (ret); \
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} else if (cvp == THR_COND_DESTROYED) { \
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return (EINVAL); \
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} \
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cvp = *cond; \
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}
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int
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_pthread_cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr)
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{
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*cond = NULL;
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return (cond_init(cond, cond_attr));
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}
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int
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_pthread_cond_destroy(pthread_cond_t *cond)
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{
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struct pthread_cond *cvp;
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int error = 0;
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if ((cvp = *cond) == THR_COND_INITIALIZER)
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error = 0;
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else if (cvp == THR_COND_DESTROYED)
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error = EINVAL;
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else {
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cvp = *cond;
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*cond = THR_COND_DESTROYED;
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/*
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* Free the memory allocated for the condition
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* variable structure:
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*/
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free(cvp);
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}
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return (error);
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}
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/*
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* Cancellation behaivor:
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* Thread may be canceled at start, if thread is canceled, it means it
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* did not get a wakeup from pthread_cond_signal(), otherwise, it is
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* not canceled.
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* Thread cancellation never cause wakeup from pthread_cond_signal()
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* to be lost.
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*/
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static int
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cond_wait_kernel(struct pthread_cond *cvp, struct pthread_mutex *mp,
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const struct timespec *abstime, int cancel)
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{
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struct pthread *curthread = _get_curthread();
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int recurse;
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int error, error2 = 0;
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error = _mutex_cv_detach(mp, &recurse);
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if (error != 0)
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return (error);
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if (cancel) {
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_thr_cancel_enter2(curthread, 0);
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error = _thr_ucond_wait((struct ucond *)&cvp->__has_kern_waiters,
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(struct umutex *)&mp->m_lock, abstime,
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CVWAIT_ABSTIME|CVWAIT_CLOCKID);
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_thr_cancel_leave(curthread, 0);
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} else {
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error = _thr_ucond_wait((struct ucond *)&cvp->__has_kern_waiters,
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(struct umutex *)&mp->m_lock, abstime,
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CVWAIT_ABSTIME|CVWAIT_CLOCKID);
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}
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/*
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* Note that PP mutex and ROBUST mutex may return
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* interesting error codes.
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*/
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if (error == 0) {
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error2 = _mutex_cv_lock(mp, recurse);
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} else if (error == EINTR || error == ETIMEDOUT) {
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error2 = _mutex_cv_lock(mp, recurse);
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if (error2 == 0 && cancel)
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_thr_testcancel(curthread);
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if (error == EINTR)
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error = 0;
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} else {
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/* We know that it didn't unlock the mutex. */
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error2 = _mutex_cv_attach(mp, recurse);
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if (error2 == 0 && cancel)
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_thr_testcancel(curthread);
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}
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return (error2 != 0 ? error2 : error);
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}
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/*
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* Thread waits in userland queue whenever possible, when thread
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* is signaled or broadcasted, it is removed from the queue, and
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* is saved in curthread's defer_waiters[] buffer, but won't be
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* woken up until mutex is unlocked.
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*/
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static int
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cond_wait_user(struct pthread_cond *cvp, struct pthread_mutex *mp,
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const struct timespec *abstime, int cancel)
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{
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struct pthread *curthread = _get_curthread();
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struct sleepqueue *sq;
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int recurse;
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int error;
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int defered;
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if (curthread->wchan != NULL)
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PANIC("thread was already on queue.");
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if (cancel)
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_thr_testcancel(curthread);
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_sleepq_lock(cvp);
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/*
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* set __has_user_waiters before unlocking mutex, this allows
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* us to check it without locking in pthread_cond_signal().
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*/
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cvp->__has_user_waiters = 1;
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defered = 0;
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(void)_mutex_cv_unlock(mp, &recurse, &defered);
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curthread->mutex_obj = mp;
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_sleepq_add(cvp, curthread);
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for(;;) {
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_thr_clear_wake(curthread);
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_sleepq_unlock(cvp);
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if (defered) {
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defered = 0;
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if ((mp->m_lock.m_owner & UMUTEX_CONTESTED) == 0)
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(void)_umtx_op_err(&mp->m_lock, UMTX_OP_MUTEX_WAKE2,
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mp->m_lock.m_flags, 0, 0);
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}
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if (curthread->nwaiter_defer > 0) {
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_thr_wake_all(curthread->defer_waiters,
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curthread->nwaiter_defer);
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curthread->nwaiter_defer = 0;
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}
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if (cancel) {
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_thr_cancel_enter2(curthread, 0);
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error = _thr_sleep(curthread, cvp->__clock_id, abstime);
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_thr_cancel_leave(curthread, 0);
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} else {
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error = _thr_sleep(curthread, cvp->__clock_id, abstime);
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}
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_sleepq_lock(cvp);
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if (curthread->wchan == NULL) {
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error = 0;
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break;
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} else if (cancel && SHOULD_CANCEL(curthread)) {
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sq = _sleepq_lookup(cvp);
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cvp->__has_user_waiters =
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_sleepq_remove(sq, curthread);
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_sleepq_unlock(cvp);
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curthread->mutex_obj = NULL;
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_mutex_cv_lock(mp, recurse);
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if (!THR_IN_CRITICAL(curthread))
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_pthread_exit(PTHREAD_CANCELED);
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else /* this should not happen */
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return (0);
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} else if (error == ETIMEDOUT) {
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sq = _sleepq_lookup(cvp);
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cvp->__has_user_waiters =
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_sleepq_remove(sq, curthread);
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break;
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}
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}
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_sleepq_unlock(cvp);
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curthread->mutex_obj = NULL;
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_mutex_cv_lock(mp, recurse);
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return (error);
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}
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static int
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cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex,
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const struct timespec *abstime, int cancel)
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{
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struct pthread *curthread = _get_curthread();
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struct pthread_cond *cvp;
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struct pthread_mutex *mp;
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int error;
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CHECK_AND_INIT_COND
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mp = *mutex;
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if ((error = _mutex_owned(curthread, mp)) != 0)
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return (error);
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if (curthread->attr.sched_policy != SCHED_OTHER ||
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(mp->m_lock.m_flags & (UMUTEX_PRIO_PROTECT|UMUTEX_PRIO_INHERIT|
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USYNC_PROCESS_SHARED)) != 0 ||
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(cvp->__flags & USYNC_PROCESS_SHARED) != 0)
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return cond_wait_kernel(cvp, mp, abstime, cancel);
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else
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return cond_wait_user(cvp, mp, abstime, cancel);
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}
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int
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_pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
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{
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return (cond_wait_common(cond, mutex, NULL, 0));
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}
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int
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__pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
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{
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return (cond_wait_common(cond, mutex, NULL, 1));
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}
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int
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_pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
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const struct timespec * abstime)
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{
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if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
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abstime->tv_nsec >= 1000000000)
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return (EINVAL);
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return (cond_wait_common(cond, mutex, abstime, 0));
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}
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int
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__pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
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const struct timespec *abstime)
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{
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if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
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abstime->tv_nsec >= 1000000000)
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return (EINVAL);
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return (cond_wait_common(cond, mutex, abstime, 1));
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}
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static int
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cond_signal_common(pthread_cond_t *cond)
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{
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struct pthread *curthread = _get_curthread();
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struct pthread *td;
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struct pthread_cond *cvp;
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struct pthread_mutex *mp;
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struct sleepqueue *sq;
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int *waddr;
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int pshared;
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/*
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* If the condition variable is statically initialized, perform dynamic
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* initialization.
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*/
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CHECK_AND_INIT_COND
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pshared = CV_PSHARED(cvp);
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_thr_ucond_signal((struct ucond *)&cvp->__has_kern_waiters);
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if (pshared || cvp->__has_user_waiters == 0)
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return (0);
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curthread = _get_curthread();
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waddr = NULL;
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_sleepq_lock(cvp);
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sq = _sleepq_lookup(cvp);
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if (sq == NULL) {
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_sleepq_unlock(cvp);
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return (0);
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}
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td = _sleepq_first(sq);
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mp = td->mutex_obj;
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cvp->__has_user_waiters = _sleepq_remove(sq, td);
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if (mp->m_owner == curthread) {
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if (curthread->nwaiter_defer >= MAX_DEFER_WAITERS) {
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_thr_wake_all(curthread->defer_waiters,
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curthread->nwaiter_defer);
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curthread->nwaiter_defer = 0;
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}
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curthread->defer_waiters[curthread->nwaiter_defer++] =
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&td->wake_addr->value;
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mp->m_flags |= PMUTEX_FLAG_DEFERED;
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} else {
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waddr = &td->wake_addr->value;
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}
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_sleepq_unlock(cvp);
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if (waddr != NULL)
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_thr_set_wake(waddr);
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return (0);
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}
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struct broadcast_arg {
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struct pthread *curthread;
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unsigned int *waddrs[MAX_DEFER_WAITERS];
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int count;
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};
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static void
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drop_cb(struct pthread *td, void *arg)
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{
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struct broadcast_arg *ba = arg;
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struct pthread_mutex *mp;
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struct pthread *curthread = ba->curthread;
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mp = td->mutex_obj;
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if (mp->m_owner == curthread) {
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if (curthread->nwaiter_defer >= MAX_DEFER_WAITERS) {
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_thr_wake_all(curthread->defer_waiters,
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curthread->nwaiter_defer);
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curthread->nwaiter_defer = 0;
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}
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curthread->defer_waiters[curthread->nwaiter_defer++] =
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&td->wake_addr->value;
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mp->m_flags |= PMUTEX_FLAG_DEFERED;
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} else {
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if (ba->count >= MAX_DEFER_WAITERS) {
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_thr_wake_all(ba->waddrs, ba->count);
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ba->count = 0;
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}
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ba->waddrs[ba->count++] = &td->wake_addr->value;
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}
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}
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static int
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cond_broadcast_common(pthread_cond_t *cond)
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{
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int pshared;
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struct pthread_cond *cvp;
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struct sleepqueue *sq;
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struct broadcast_arg ba;
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/*
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* If the condition variable is statically initialized, perform dynamic
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* initialization.
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*/
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CHECK_AND_INIT_COND
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pshared = CV_PSHARED(cvp);
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_thr_ucond_broadcast((struct ucond *)&cvp->__has_kern_waiters);
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if (pshared || cvp->__has_user_waiters == 0)
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return (0);
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ba.curthread = _get_curthread();
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ba.count = 0;
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_sleepq_lock(cvp);
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sq = _sleepq_lookup(cvp);
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if (sq == NULL) {
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_sleepq_unlock(cvp);
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return (0);
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}
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_sleepq_drop(sq, drop_cb, &ba);
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cvp->__has_user_waiters = 0;
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_sleepq_unlock(cvp);
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if (ba.count > 0)
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_thr_wake_all(ba.waddrs, ba.count);
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return (0);
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}
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int
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_pthread_cond_signal(pthread_cond_t * cond)
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{
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return (cond_signal_common(cond));
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}
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int
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_pthread_cond_broadcast(pthread_cond_t * cond)
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{
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return (cond_broadcast_common(cond));
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}
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