843d4004b3
signals instead of having more intricate knowledge of thread state within signal handling. Simplify signal code because of above (by David Xu). Use macros for libpthread usage of pthread_cleanup_push() and pthread_cleanup_pop(). This removes some instances of malloc() and free() from the semaphore and pthread_once() implementations. When single threaded and forking(), make sure that the current thread's signal mask is inherited by the forked thread. Use private mutexes for libc and libpthread. Signals are deferred while threads hold private mutexes. This fix also breaks www/linuxpluginwrapper; a patch that fixes it is at http://people.freebsd.org/~deischen/kse/linuxpluginwrapper.diff Fix race condition in condition variables where handling a signal (pthread_kill() or kill()) may not see a wakeup (pthread_cond_signal() or pthread_cond_broadcast()). In collaboration with: davidxu
833 lines
22 KiB
C
833 lines
22 KiB
C
/*
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* Copyright (c) 1995 John Birrell <jb@cimlogic.com.au>.
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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, this list of conditions and the following 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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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by John Birrell.
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* 4. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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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 "thr_private.h"
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#define THR_IN_CONDQ(thr) (((thr)->sflags & THR_FLAGS_IN_SYNCQ) != 0)
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#define THR_CONDQ_SET(thr) (thr)->sflags |= THR_FLAGS_IN_SYNCQ
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#define THR_CONDQ_CLEAR(thr) (thr)->sflags &= ~THR_FLAGS_IN_SYNCQ
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/*
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* Prototypes
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*/
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static inline struct pthread *cond_queue_deq(pthread_cond_t);
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static inline void cond_queue_remove(pthread_cond_t, pthread_t);
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static inline void cond_queue_enq(pthread_cond_t, pthread_t);
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static void cond_wait_backout(void *);
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static inline void check_continuation(struct pthread *,
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struct pthread_cond *, pthread_mutex_t *);
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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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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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enum pthread_cond_type type;
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pthread_cond_t pcond;
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int flags;
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int rval = 0;
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if (cond == NULL)
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rval = EINVAL;
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else {
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/*
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* Check if a pointer to a condition variable attribute
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* structure was passed by the caller:
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*/
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if (cond_attr != NULL && *cond_attr != NULL) {
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/* Default to a fast condition variable: */
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type = (*cond_attr)->c_type;
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flags = (*cond_attr)->c_flags;
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} else {
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/* Default to a fast condition variable: */
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type = COND_TYPE_FAST;
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flags = 0;
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}
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/* Process according to condition variable type: */
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switch (type) {
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/* Fast condition variable: */
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case COND_TYPE_FAST:
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/* Nothing to do here. */
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break;
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/* Trap invalid condition variable types: */
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default:
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/* Return an invalid argument error: */
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rval = EINVAL;
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break;
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}
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/* Check for no errors: */
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if (rval == 0) {
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if ((pcond = (pthread_cond_t)
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malloc(sizeof(struct pthread_cond))) == NULL) {
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rval = ENOMEM;
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} else if (_lock_init(&pcond->c_lock, LCK_ADAPTIVE,
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_thr_lock_wait, _thr_lock_wakeup) != 0) {
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free(pcond);
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rval = ENOMEM;
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} else {
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/*
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* Initialise the condition variable
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* structure:
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*/
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TAILQ_INIT(&pcond->c_queue);
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pcond->c_flags = COND_FLAGS_INITED;
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pcond->c_type = type;
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pcond->c_mutex = NULL;
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pcond->c_seqno = 0;
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*cond = pcond;
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}
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}
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}
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/* Return the completion status: */
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return (rval);
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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 *cv;
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struct pthread *curthread = _get_curthread();
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int rval = 0;
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if (cond == NULL || *cond == NULL)
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rval = EINVAL;
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else {
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/* Lock the condition variable structure: */
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THR_LOCK_ACQUIRE(curthread, &(*cond)->c_lock);
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/*
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* NULL the caller's pointer now that the condition
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* variable has been destroyed:
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*/
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cv = *cond;
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*cond = NULL;
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/* Unlock the condition variable structure: */
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THR_LOCK_RELEASE(curthread, &cv->c_lock);
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/* Free the cond lock structure: */
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_lock_destroy(&cv->c_lock);
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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(cv);
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}
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/* Return the completion status: */
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return (rval);
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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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struct pthread *curthread = _get_curthread();
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int rval = 0;
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int done = 0;
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int mutex_locked = 1;
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int seqno;
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if (cond == NULL)
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return (EINVAL);
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/*
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* If the condition variable is statically initialized,
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* perform the dynamic initialization:
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*/
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if (*cond == NULL &&
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(rval = pthread_cond_init(cond, NULL)) != 0)
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return (rval);
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if (!_kse_isthreaded())
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_kse_setthreaded(1);
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/*
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* Enter a loop waiting for a condition signal or broadcast
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* to wake up this thread. A loop is needed in case the waiting
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* thread is interrupted by a signal to execute a signal handler.
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* It is not (currently) possible to remain in the waiting queue
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* while running a handler. Instead, the thread is interrupted
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* and backed out of the waiting queue prior to executing the
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* signal handler.
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*/
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/* Lock the condition variable structure: */
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THR_LOCK_ACQUIRE(curthread, &(*cond)->c_lock);
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seqno = (*cond)->c_seqno;
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do {
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/*
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* If the condvar was statically allocated, properly
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* initialize the tail queue.
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*/
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if (((*cond)->c_flags & COND_FLAGS_INITED) == 0) {
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TAILQ_INIT(&(*cond)->c_queue);
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(*cond)->c_flags |= COND_FLAGS_INITED;
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}
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/* Process according to condition variable type: */
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switch ((*cond)->c_type) {
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/* Fast condition variable: */
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case COND_TYPE_FAST:
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if ((mutex == NULL) || (((*cond)->c_mutex != NULL) &&
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((*cond)->c_mutex != *mutex))) {
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/* Return invalid argument error: */
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rval = EINVAL;
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} else {
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/* Reset the timeout and interrupted flags: */
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curthread->timeout = 0;
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curthread->interrupted = 0;
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/*
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* Queue the running thread for the condition
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* variable:
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*/
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cond_queue_enq(*cond, curthread);
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/* Wait forever: */
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curthread->wakeup_time.tv_sec = -1;
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/* Unlock the mutex: */
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if (mutex_locked &&
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((rval = _mutex_cv_unlock(mutex)) != 0)) {
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/*
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* Cannot unlock the mutex, so remove
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* the running thread from the condition
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* variable queue:
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*/
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cond_queue_remove(*cond, curthread);
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}
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else {
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/* Remember the mutex: */
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(*cond)->c_mutex = *mutex;
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/*
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* Don't unlock the mutex the next
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* time through the loop (if the
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* thread has to be requeued after
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* handling a signal).
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*/
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mutex_locked = 0;
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/*
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* This thread is active and is in a
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* critical region (holding the cv
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* lock); we should be able to safely
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* set the state.
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*/
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THR_SCHED_LOCK(curthread, curthread);
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THR_SET_STATE(curthread, PS_COND_WAIT);
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/* Remember the CV: */
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curthread->data.cond = *cond;
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curthread->sigbackout = cond_wait_backout;
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THR_SCHED_UNLOCK(curthread, curthread);
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/* Unlock the CV structure: */
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THR_LOCK_RELEASE(curthread,
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&(*cond)->c_lock);
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/* Schedule the next thread: */
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_thr_sched_switch(curthread);
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/*
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* XXX - This really isn't a good check
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* since there can be more than one
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* thread waiting on the CV. Signals
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* sent to threads waiting on mutexes
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* or CVs should really be deferred
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* until the threads are no longer
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* waiting, but POSIX says that signals
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* should be sent "as soon as possible".
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*/
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done = (seqno != (*cond)->c_seqno);
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if (done && !THR_IN_CONDQ(curthread)) {
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/*
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* The thread is dequeued, so
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* it is safe to clear these.
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*/
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curthread->data.cond = NULL;
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curthread->sigbackout = NULL;
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check_continuation(curthread,
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NULL, mutex);
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return (_mutex_cv_lock(mutex));
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}
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/* Relock the CV structure: */
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THR_LOCK_ACQUIRE(curthread,
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&(*cond)->c_lock);
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/*
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* Clear these after taking the lock to
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* prevent a race condition where a
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* signal can arrive before dequeueing
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* the thread.
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*/
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curthread->data.cond = NULL;
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curthread->sigbackout = NULL;
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done = (seqno != (*cond)->c_seqno);
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if (THR_IN_CONDQ(curthread)) {
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cond_queue_remove(*cond,
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curthread);
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/* Check for no more waiters: */
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if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
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(*cond)->c_mutex = NULL;
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}
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}
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}
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break;
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/* Trap invalid condition variable types: */
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default:
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/* Return an invalid argument error: */
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rval = EINVAL;
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break;
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}
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check_continuation(curthread, *cond,
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mutex_locked ? NULL : mutex);
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} while ((done == 0) && (rval == 0));
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/* Unlock the condition variable structure: */
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THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
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if (mutex_locked == 0)
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_mutex_cv_lock(mutex);
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/* Return the completion status: */
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return (rval);
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}
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__strong_reference(_pthread_cond_wait, _thr_cond_wait);
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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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struct pthread *curthread = _get_curthread();
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int ret;
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_thr_cancel_enter(curthread);
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ret = _pthread_cond_wait(cond, mutex);
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_thr_cancel_leave(curthread, 1);
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return (ret);
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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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struct pthread *curthread = _get_curthread();
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int rval = 0;
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int done = 0;
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int mutex_locked = 1;
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int seqno;
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THR_ASSERT(curthread->locklevel == 0,
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"cv_timedwait: locklevel is not zero!");
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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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/*
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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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if (*cond == NULL && (rval = pthread_cond_init(cond, NULL)) != 0)
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return (rval);
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if (!_kse_isthreaded())
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_kse_setthreaded(1);
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/*
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* Enter a loop waiting for a condition signal or broadcast
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* to wake up this thread. A loop is needed in case the waiting
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* thread is interrupted by a signal to execute a signal handler.
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* It is not (currently) possible to remain in the waiting queue
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* while running a handler. Instead, the thread is interrupted
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* and backed out of the waiting queue prior to executing the
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* signal handler.
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*/
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/* Lock the condition variable structure: */
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THR_LOCK_ACQUIRE(curthread, &(*cond)->c_lock);
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seqno = (*cond)->c_seqno;
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do {
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/*
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* If the condvar was statically allocated, properly
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* initialize the tail queue.
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*/
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if (((*cond)->c_flags & COND_FLAGS_INITED) == 0) {
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TAILQ_INIT(&(*cond)->c_queue);
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(*cond)->c_flags |= COND_FLAGS_INITED;
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}
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/* Process according to condition variable type: */
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switch ((*cond)->c_type) {
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/* Fast condition variable: */
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case COND_TYPE_FAST:
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if ((mutex == NULL) || (((*cond)->c_mutex != NULL) &&
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((*cond)->c_mutex != *mutex))) {
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/* Return invalid argument error: */
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rval = EINVAL;
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} else {
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/* Set the wakeup time: */
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curthread->wakeup_time.tv_sec = abstime->tv_sec;
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curthread->wakeup_time.tv_nsec =
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abstime->tv_nsec;
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/* Reset the timeout and interrupted flags: */
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curthread->timeout = 0;
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curthread->interrupted = 0;
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/*
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* Queue the running thread for the condition
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* variable:
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*/
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cond_queue_enq(*cond, curthread);
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/* Unlock the mutex: */
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if (mutex_locked &&
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((rval = _mutex_cv_unlock(mutex)) != 0)) {
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/*
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* Cannot unlock the mutex; remove the
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* running thread from the condition
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* variable queue:
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*/
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cond_queue_remove(*cond, curthread);
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} else {
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/* Remember the mutex: */
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(*cond)->c_mutex = *mutex;
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/*
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* Don't unlock the mutex the next
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* time through the loop (if the
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* thread has to be requeued after
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* handling a signal).
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*/
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mutex_locked = 0;
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/*
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* This thread is active and is in a
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* critical region (holding the cv
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* lock); we should be able to safely
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* set the state.
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*/
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THR_SCHED_LOCK(curthread, curthread);
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THR_SET_STATE(curthread, PS_COND_WAIT);
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/* Remember the CV: */
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curthread->data.cond = *cond;
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curthread->sigbackout = cond_wait_backout;
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THR_SCHED_UNLOCK(curthread, curthread);
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/* Unlock the CV structure: */
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THR_LOCK_RELEASE(curthread,
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&(*cond)->c_lock);
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/* Schedule the next thread: */
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_thr_sched_switch(curthread);
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/*
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* XXX - This really isn't a good check
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|
* since there can be more than one
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* thread waiting on the CV. Signals
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|
* sent to threads waiting on mutexes
|
|
* or CVs should really be deferred
|
|
* until the threads are no longer
|
|
* waiting, but POSIX says that signals
|
|
* should be sent "as soon as possible".
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|
*/
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done = (seqno != (*cond)->c_seqno);
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if (done && !THR_IN_CONDQ(curthread)) {
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/*
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* The thread is dequeued, so
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* it is safe to clear these.
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*/
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curthread->data.cond = NULL;
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curthread->sigbackout = NULL;
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check_continuation(curthread,
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NULL, mutex);
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return (_mutex_cv_lock(mutex));
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}
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/* Relock the CV structure: */
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THR_LOCK_ACQUIRE(curthread,
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&(*cond)->c_lock);
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/*
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* Clear these after taking the lock to
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* prevent a race condition where a
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* signal can arrive before dequeueing
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* the thread.
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*/
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curthread->data.cond = NULL;
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curthread->sigbackout = NULL;
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done = (seqno != (*cond)->c_seqno);
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if (THR_IN_CONDQ(curthread)) {
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cond_queue_remove(*cond,
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curthread);
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/* Check for no more waiters: */
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if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
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(*cond)->c_mutex = NULL;
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}
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|
|
if (curthread->timeout != 0) {
|
|
/* The wait timedout. */
|
|
rval = ETIMEDOUT;
|
|
}
|
|
}
|
|
}
|
|
break;
|
|
|
|
/* Trap invalid condition variable types: */
|
|
default:
|
|
/* Return an invalid argument error: */
|
|
rval = EINVAL;
|
|
break;
|
|
}
|
|
|
|
check_continuation(curthread, *cond,
|
|
mutex_locked ? NULL : mutex);
|
|
} while ((done == 0) && (rval == 0));
|
|
|
|
/* Unlock the condition variable structure: */
|
|
THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
|
|
|
|
if (mutex_locked == 0)
|
|
_mutex_cv_lock(mutex);
|
|
|
|
/* Return the completion status: */
|
|
return (rval);
|
|
}
|
|
|
|
int
|
|
__pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
|
|
const struct timespec *abstime)
|
|
{
|
|
struct pthread *curthread = _get_curthread();
|
|
int ret;
|
|
|
|
_thr_cancel_enter(curthread);
|
|
ret = _pthread_cond_timedwait(cond, mutex, abstime);
|
|
_thr_cancel_leave(curthread, 1);
|
|
return (ret);
|
|
}
|
|
|
|
|
|
int
|
|
_pthread_cond_signal(pthread_cond_t * cond)
|
|
{
|
|
struct pthread *curthread = _get_curthread();
|
|
struct pthread *pthread;
|
|
struct kse_mailbox *kmbx;
|
|
int rval = 0;
|
|
|
|
THR_ASSERT(curthread->locklevel == 0,
|
|
"cv_timedwait: locklevel is not zero!");
|
|
if (cond == NULL)
|
|
rval = EINVAL;
|
|
/*
|
|
* If the condition variable is statically initialized, perform dynamic
|
|
* initialization.
|
|
*/
|
|
else if (*cond != NULL || (rval = pthread_cond_init(cond, NULL)) == 0) {
|
|
/* Lock the condition variable structure: */
|
|
THR_LOCK_ACQUIRE(curthread, &(*cond)->c_lock);
|
|
|
|
/* Process according to condition variable type: */
|
|
switch ((*cond)->c_type) {
|
|
/* Fast condition variable: */
|
|
case COND_TYPE_FAST:
|
|
/* Increment the sequence number: */
|
|
(*cond)->c_seqno++;
|
|
|
|
/*
|
|
* Wakeups have to be done with the CV lock held;
|
|
* otherwise there is a race condition where the
|
|
* thread can timeout, run on another KSE, and enter
|
|
* another blocking state (including blocking on a CV).
|
|
*/
|
|
if ((pthread = TAILQ_FIRST(&(*cond)->c_queue))
|
|
!= NULL) {
|
|
THR_SCHED_LOCK(curthread, pthread);
|
|
cond_queue_remove(*cond, pthread);
|
|
pthread->sigbackout = NULL;
|
|
if ((pthread->kseg == curthread->kseg) &&
|
|
(pthread->active_priority >
|
|
curthread->active_priority))
|
|
curthread->critical_yield = 1;
|
|
kmbx = _thr_setrunnable_unlocked(pthread);
|
|
THR_SCHED_UNLOCK(curthread, pthread);
|
|
if (kmbx != NULL)
|
|
kse_wakeup(kmbx);
|
|
}
|
|
/* Check for no more waiters: */
|
|
if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
|
|
(*cond)->c_mutex = NULL;
|
|
break;
|
|
|
|
/* Trap invalid condition variable types: */
|
|
default:
|
|
/* Return an invalid argument error: */
|
|
rval = EINVAL;
|
|
break;
|
|
}
|
|
|
|
/* Unlock the condition variable structure: */
|
|
THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
|
|
}
|
|
|
|
/* Return the completion status: */
|
|
return (rval);
|
|
}
|
|
|
|
__strong_reference(_pthread_cond_signal, _thr_cond_signal);
|
|
|
|
int
|
|
_pthread_cond_broadcast(pthread_cond_t * cond)
|
|
{
|
|
struct pthread *curthread = _get_curthread();
|
|
struct pthread *pthread;
|
|
struct kse_mailbox *kmbx;
|
|
int rval = 0;
|
|
|
|
THR_ASSERT(curthread->locklevel == 0,
|
|
"cv_timedwait: locklevel is not zero!");
|
|
if (cond == NULL)
|
|
rval = EINVAL;
|
|
/*
|
|
* If the condition variable is statically initialized, perform dynamic
|
|
* initialization.
|
|
*/
|
|
else if (*cond != NULL || (rval = pthread_cond_init(cond, NULL)) == 0) {
|
|
/* Lock the condition variable structure: */
|
|
THR_LOCK_ACQUIRE(curthread, &(*cond)->c_lock);
|
|
|
|
/* Process according to condition variable type: */
|
|
switch ((*cond)->c_type) {
|
|
/* Fast condition variable: */
|
|
case COND_TYPE_FAST:
|
|
/* Increment the sequence number: */
|
|
(*cond)->c_seqno++;
|
|
|
|
/*
|
|
* Enter a loop to bring all threads off the
|
|
* condition queue:
|
|
*/
|
|
while ((pthread = TAILQ_FIRST(&(*cond)->c_queue))
|
|
!= NULL) {
|
|
THR_SCHED_LOCK(curthread, pthread);
|
|
cond_queue_remove(*cond, pthread);
|
|
pthread->sigbackout = NULL;
|
|
if ((pthread->kseg == curthread->kseg) &&
|
|
(pthread->active_priority >
|
|
curthread->active_priority))
|
|
curthread->critical_yield = 1;
|
|
kmbx = _thr_setrunnable_unlocked(pthread);
|
|
THR_SCHED_UNLOCK(curthread, pthread);
|
|
if (kmbx != NULL)
|
|
kse_wakeup(kmbx);
|
|
}
|
|
|
|
/* There are no more waiting threads: */
|
|
(*cond)->c_mutex = NULL;
|
|
break;
|
|
|
|
/* Trap invalid condition variable types: */
|
|
default:
|
|
/* Return an invalid argument error: */
|
|
rval = EINVAL;
|
|
break;
|
|
}
|
|
|
|
/* Unlock the condition variable structure: */
|
|
THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
|
|
}
|
|
|
|
/* Return the completion status: */
|
|
return (rval);
|
|
}
|
|
|
|
__strong_reference(_pthread_cond_broadcast, _thr_cond_broadcast);
|
|
|
|
static inline void
|
|
check_continuation(struct pthread *curthread, struct pthread_cond *cond,
|
|
pthread_mutex_t *mutex)
|
|
{
|
|
if ((curthread->interrupted != 0) &&
|
|
(curthread->continuation != NULL)) {
|
|
if (cond != NULL)
|
|
/* Unlock the condition variable structure: */
|
|
THR_LOCK_RELEASE(curthread, &cond->c_lock);
|
|
/*
|
|
* Note that even though this thread may have been
|
|
* canceled, POSIX requires that the mutex be
|
|
* reaquired prior to cancellation.
|
|
*/
|
|
if (mutex != NULL)
|
|
_mutex_cv_lock(mutex);
|
|
curthread->continuation((void *) curthread);
|
|
PANIC("continuation returned in pthread_cond_wait.\n");
|
|
}
|
|
}
|
|
|
|
static void
|
|
cond_wait_backout(void *arg)
|
|
{
|
|
struct pthread *curthread = (struct pthread *)arg;
|
|
pthread_cond_t cond;
|
|
|
|
cond = curthread->data.cond;
|
|
if (cond != NULL) {
|
|
/* Lock the condition variable structure: */
|
|
THR_LOCK_ACQUIRE(curthread, &cond->c_lock);
|
|
|
|
/* Process according to condition variable type: */
|
|
switch (cond->c_type) {
|
|
/* Fast condition variable: */
|
|
case COND_TYPE_FAST:
|
|
cond_queue_remove(cond, curthread);
|
|
|
|
/* Check for no more waiters: */
|
|
if (TAILQ_FIRST(&cond->c_queue) == NULL)
|
|
cond->c_mutex = NULL;
|
|
break;
|
|
|
|
default:
|
|
break;
|
|
}
|
|
|
|
/* Unlock the condition variable structure: */
|
|
THR_LOCK_RELEASE(curthread, &cond->c_lock);
|
|
}
|
|
/* No need to call this again. */
|
|
curthread->sigbackout = NULL;
|
|
}
|
|
|
|
/*
|
|
* Dequeue a waiting thread from the head of a condition queue in
|
|
* descending priority order.
|
|
*/
|
|
static inline struct pthread *
|
|
cond_queue_deq(pthread_cond_t cond)
|
|
{
|
|
struct pthread *pthread;
|
|
|
|
while ((pthread = TAILQ_FIRST(&cond->c_queue)) != NULL) {
|
|
TAILQ_REMOVE(&cond->c_queue, pthread, sqe);
|
|
THR_CONDQ_CLEAR(pthread);
|
|
if ((pthread->timeout == 0) && (pthread->interrupted == 0))
|
|
/*
|
|
* Only exit the loop when we find a thread
|
|
* that hasn't timed out or been canceled;
|
|
* those threads are already running and don't
|
|
* need their run state changed.
|
|
*/
|
|
break;
|
|
}
|
|
|
|
return (pthread);
|
|
}
|
|
|
|
/*
|
|
* Remove a waiting thread from a condition queue in descending priority
|
|
* order.
|
|
*/
|
|
static inline void
|
|
cond_queue_remove(pthread_cond_t cond, struct pthread *pthread)
|
|
{
|
|
/*
|
|
* Because pthread_cond_timedwait() can timeout as well
|
|
* as be signaled by another thread, it is necessary to
|
|
* guard against removing the thread from the queue if
|
|
* it isn't in the queue.
|
|
*/
|
|
if (THR_IN_CONDQ(pthread)) {
|
|
TAILQ_REMOVE(&cond->c_queue, pthread, sqe);
|
|
THR_CONDQ_CLEAR(pthread);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Enqueue a waiting thread to a condition queue in descending priority
|
|
* order.
|
|
*/
|
|
static inline void
|
|
cond_queue_enq(pthread_cond_t cond, struct pthread *pthread)
|
|
{
|
|
struct pthread *tid = TAILQ_LAST(&cond->c_queue, cond_head);
|
|
|
|
THR_ASSERT(!THR_IN_SYNCQ(pthread),
|
|
"cond_queue_enq: thread already queued!");
|
|
|
|
/*
|
|
* For the common case of all threads having equal priority,
|
|
* we perform a quick check against the priority of the thread
|
|
* at the tail of the queue.
|
|
*/
|
|
if ((tid == NULL) || (pthread->active_priority <= tid->active_priority))
|
|
TAILQ_INSERT_TAIL(&cond->c_queue, pthread, sqe);
|
|
else {
|
|
tid = TAILQ_FIRST(&cond->c_queue);
|
|
while (pthread->active_priority <= tid->active_priority)
|
|
tid = TAILQ_NEXT(tid, sqe);
|
|
TAILQ_INSERT_BEFORE(tid, pthread, sqe);
|
|
}
|
|
THR_CONDQ_SET(pthread);
|
|
pthread->data.cond = cond;
|
|
}
|