764 lines
20 KiB
C
764 lines
20 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 "pthread_private.h"
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/*
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* Prototypes
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*/
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static inline pthread_t 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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__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_wait, pthread_cond_wait);
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__weak_reference(_pthread_cond_timedwait, pthread_cond_timedwait);
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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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/* Reinitialize a condition variable to defaults. */
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int
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_cond_reinit(pthread_cond_t *cond)
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{
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int ret = 0;
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if (cond == NULL)
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ret = EINVAL;
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else if (*cond == NULL)
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ret = pthread_cond_init(cond, NULL);
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else {
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/*
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* Initialize the condition variable structure:
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*/
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TAILQ_INIT(&(*cond)->c_queue);
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(*cond)->c_flags = COND_FLAGS_INITED;
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(*cond)->c_type = COND_TYPE_FAST;
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(*cond)->c_mutex = NULL;
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(*cond)->c_seqno = 0;
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memset(&(*cond)->lock, 0, sizeof((*cond)->lock));
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}
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return (ret);
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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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enum pthread_cond_type type;
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pthread_cond_t pcond;
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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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} else {
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/* Default to a fast condition variable: */
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type = COND_TYPE_FAST;
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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 {
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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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memset(&pcond->lock,0,sizeof(pcond->lock));
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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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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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_SPINLOCK(&(*cond)->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(*cond);
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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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*cond = NULL;
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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 interrupted = 0;
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int unlock_mutex = 1;
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int seqno;
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_thread_enter_cancellation_point();
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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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/*
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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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do {
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/* Lock the condition variable structure: */
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_SPINLOCK(&(*cond)->lock);
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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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/* Unlock the condition variable structure: */
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_SPINUNLOCK(&(*cond)->lock);
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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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/* Remember the mutex and sequence number: */
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(*cond)->c_mutex = *mutex;
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seqno = (*cond)->c_seqno;
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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 ((unlock_mutex != 0) &&
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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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/* Check for no more waiters: */
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if (TAILQ_FIRST(&(*cond)->c_queue) ==
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NULL)
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(*cond)->c_mutex = NULL;
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/* Unlock the condition variable structure: */
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_SPINUNLOCK(&(*cond)->lock);
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}
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else {
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/*
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* Don't unlock the mutex in the event
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* this thread has to be requeued in
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* condition variable queue:
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*/
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unlock_mutex = 0;
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/*
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* Schedule the next thread and unlock
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* the condition variable structure:
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*/
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_thread_kern_sched_state_unlock(PS_COND_WAIT,
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&(*cond)->lock, __FILE__, __LINE__);
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done = (seqno != (*cond)->c_seqno);
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if ((curthread->flags &
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PTHREAD_FLAGS_IN_CONDQ) != 0) {
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/*
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* Lock the condition variable
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* while removing the thread.
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*/
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_SPINLOCK(&(*cond)->lock);
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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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_SPINUNLOCK(&(*cond)->lock);
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}
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/*
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* Save the interrupted flag; locking
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* the mutex will destroy it.
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*/
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interrupted = curthread->interrupted;
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/*
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* Note that even though this thread may have
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* been canceled, POSIX requires that the mutex
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* be reaquired prior to cancellation.
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*/
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rval = _mutex_cv_lock(mutex);
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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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/* Unlock the condition variable structure: */
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_SPINUNLOCK(&(*cond)->lock);
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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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if ((interrupted != 0) && (curthread->continuation != NULL))
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curthread->continuation((void *) curthread);
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} while ((done == 0) && (rval == 0));
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_thread_leave_cancellation_point();
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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_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 interrupted = 0;
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int unlock_mutex = 1;
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int seqno;
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_thread_enter_cancellation_point();
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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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/*
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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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do {
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/* Lock the condition variable structure: */
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_SPINLOCK(&(*cond)->lock);
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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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/* Unlock the condition variable structure: */
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_SPINUNLOCK(&(*cond)->lock);
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} else {
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/* Set the wakeup time: */
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curthread->wakeup_time.tv_sec =
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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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/* Remember the mutex and sequence number: */
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(*cond)->c_mutex = *mutex;
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seqno = (*cond)->c_seqno;
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/* Unlock the mutex: */
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if ((unlock_mutex != 0) &&
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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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/* 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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/* Unlock the condition variable structure: */
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_SPINUNLOCK(&(*cond)->lock);
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} else {
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/*
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* Don't unlock the mutex in the event
|
|
* this thread has to be requeued in
|
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* condition variable queue:
|
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*/
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unlock_mutex = 0;
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|
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/*
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* Schedule the next thread and unlock
|
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* the condition variable structure:
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*/
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_thread_kern_sched_state_unlock(PS_COND_WAIT,
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&(*cond)->lock, __FILE__, __LINE__);
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done = (seqno != (*cond)->c_seqno);
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|
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/*
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* Check if the wait timedout, was
|
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* interrupted (canceled), or needs to
|
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* be resumed after handling a signal.
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*/
|
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if ((curthread->timeout == 0) &&
|
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(curthread->interrupted == 0) &&
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(done != 0)) {
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/* Lock the mutex: */
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rval = _mutex_cv_lock(mutex);
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} else {
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/* Lock the CV structure: */
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_SPINLOCK(&(*cond)->lock);
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/*
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* The wait timed out; remove
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* the thread from the condition
|
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* variable queue:
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*/
|
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cond_queue_remove(*cond,
|
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curthread);
|
|
|
|
/* Check for no more waiters: */
|
|
if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
|
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(*cond)->c_mutex = NULL;
|
|
|
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/* Unock the CV structure: */
|
|
_SPINUNLOCK(&(*cond)->lock);
|
|
|
|
/* Return a timeout error: */
|
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if (curthread->timeout != 0)
|
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rval = ETIMEDOUT;
|
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/*
|
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* Save the interrupted flag;
|
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* locking the mutex will
|
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* destroy it.
|
|
*/
|
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interrupted = curthread->interrupted;
|
|
|
|
/*
|
|
* Lock the mutex and ignore any
|
|
* errors. Note that even though
|
|
* this thread may have been
|
|
* canceled, POSIX requires that
|
|
* the mutex be reaquired prior
|
|
* to cancellation.
|
|
*/
|
|
(void)_mutex_cv_lock(mutex);
|
|
}
|
|
}
|
|
}
|
|
break;
|
|
|
|
/* Trap invalid condition variable types: */
|
|
default:
|
|
/* Unlock the condition variable structure: */
|
|
_SPINUNLOCK(&(*cond)->lock);
|
|
|
|
/* Return an invalid argument error: */
|
|
rval = EINVAL;
|
|
break;
|
|
}
|
|
|
|
if ((interrupted != 0) && (curthread->continuation != NULL))
|
|
curthread->continuation((void *) curthread);
|
|
} while ((done == 0) && (rval == 0));
|
|
|
|
_thread_leave_cancellation_point();
|
|
|
|
/* Return the completion status: */
|
|
return (rval);
|
|
}
|
|
|
|
int
|
|
_pthread_cond_signal(pthread_cond_t * cond)
|
|
{
|
|
int rval = 0;
|
|
pthread_t pthread;
|
|
|
|
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) {
|
|
/*
|
|
* Defer signals to protect the scheduling queues
|
|
* from access by the signal handler:
|
|
*/
|
|
_thread_kern_sig_defer();
|
|
|
|
/* Lock the condition variable structure: */
|
|
_SPINLOCK(&(*cond)->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++;
|
|
|
|
if ((pthread = cond_queue_deq(*cond)) != NULL) {
|
|
/*
|
|
* Unless the thread is currently suspended,
|
|
* allow it to run. If the thread is suspended,
|
|
* make a note that the thread isn't in a wait
|
|
* queue any more.
|
|
*/
|
|
if (pthread->state != PS_SUSPENDED)
|
|
PTHREAD_NEW_STATE(pthread,PS_RUNNING);
|
|
else
|
|
pthread->suspended = SUSP_NOWAIT;
|
|
}
|
|
|
|
/* 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: */
|
|
_SPINUNLOCK(&(*cond)->lock);
|
|
|
|
/*
|
|
* Undefer and handle pending signals, yielding if
|
|
* necessary:
|
|
*/
|
|
_thread_kern_sig_undefer();
|
|
}
|
|
|
|
/* Return the completion status: */
|
|
return (rval);
|
|
}
|
|
|
|
int
|
|
_pthread_cond_broadcast(pthread_cond_t * cond)
|
|
{
|
|
int rval = 0;
|
|
pthread_t pthread;
|
|
|
|
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) {
|
|
/*
|
|
* Defer signals to protect the scheduling queues
|
|
* from access by the signal handler:
|
|
*/
|
|
_thread_kern_sig_defer();
|
|
|
|
/* Lock the condition variable structure: */
|
|
_SPINLOCK(&(*cond)->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 = cond_queue_deq(*cond)) != NULL) {
|
|
/*
|
|
* Unless the thread is currently suspended,
|
|
* allow it to run. If the thread is suspended,
|
|
* make a note that the thread isn't in a wait
|
|
* queue any more.
|
|
*/
|
|
if (pthread->state != PS_SUSPENDED)
|
|
PTHREAD_NEW_STATE(pthread,PS_RUNNING);
|
|
else
|
|
pthread->suspended = SUSP_NOWAIT;
|
|
}
|
|
|
|
/* 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: */
|
|
_SPINUNLOCK(&(*cond)->lock);
|
|
|
|
/*
|
|
* Undefer and handle pending signals, yielding if
|
|
* necessary:
|
|
*/
|
|
_thread_kern_sig_undefer();
|
|
}
|
|
|
|
/* Return the completion status: */
|
|
return (rval);
|
|
}
|
|
|
|
void
|
|
_cond_wait_backout(pthread_t pthread)
|
|
{
|
|
pthread_cond_t cond;
|
|
|
|
cond = pthread->data.cond;
|
|
if (cond != NULL) {
|
|
/*
|
|
* Defer signals to protect the scheduling queues
|
|
* from access by the signal handler:
|
|
*/
|
|
_thread_kern_sig_defer();
|
|
|
|
/* Lock the condition variable structure: */
|
|
_SPINLOCK(&cond->lock);
|
|
|
|
/* Process according to condition variable type: */
|
|
switch (cond->c_type) {
|
|
/* Fast condition variable: */
|
|
case COND_TYPE_FAST:
|
|
cond_queue_remove(cond, pthread);
|
|
|
|
/* Check for no more waiters: */
|
|
if (TAILQ_FIRST(&cond->c_queue) == NULL)
|
|
cond->c_mutex = NULL;
|
|
break;
|
|
|
|
default:
|
|
break;
|
|
}
|
|
|
|
/* Unlock the condition variable structure: */
|
|
_SPINUNLOCK(&cond->lock);
|
|
|
|
/*
|
|
* Undefer and handle pending signals, yielding if
|
|
* necessary:
|
|
*/
|
|
_thread_kern_sig_undefer();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Dequeue a waiting thread from the head of a condition queue in
|
|
* descending priority order.
|
|
*/
|
|
static inline pthread_t
|
|
cond_queue_deq(pthread_cond_t cond)
|
|
{
|
|
pthread_t pthread;
|
|
|
|
while ((pthread = TAILQ_FIRST(&cond->c_queue)) != NULL) {
|
|
TAILQ_REMOVE(&cond->c_queue, pthread, sqe);
|
|
pthread->flags &= ~PTHREAD_FLAGS_IN_CONDQ;
|
|
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, pthread_t 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 (pthread->flags & PTHREAD_FLAGS_IN_CONDQ) {
|
|
TAILQ_REMOVE(&cond->c_queue, pthread, sqe);
|
|
pthread->flags &= ~PTHREAD_FLAGS_IN_CONDQ;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Enqueue a waiting thread to a condition queue in descending priority
|
|
* order.
|
|
*/
|
|
static inline void
|
|
cond_queue_enq(pthread_cond_t cond, pthread_t pthread)
|
|
{
|
|
pthread_t tid = TAILQ_LAST(&cond->c_queue, cond_head);
|
|
|
|
PTHREAD_ASSERT_NOT_IN_SYNCQ(pthread);
|
|
|
|
/*
|
|
* 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);
|
|
}
|
|
pthread->flags |= PTHREAD_FLAGS_IN_CONDQ;
|
|
pthread->data.cond = cond;
|
|
}
|