1365 lines
35 KiB
C
1365 lines
35 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 <sys/param.h>
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#include <sys/queue.h>
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#ifdef _THREAD_SAFE
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#include <pthread.h>
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#include "pthread_private.h"
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#if defined(_PTHREADS_INVARIANTS)
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#define _MUTEX_INIT_LINK(m) do { \
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(m)->m_qe.tqe_prev = NULL; \
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(m)->m_qe.tqe_next = NULL; \
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} while (0)
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#define _MUTEX_ASSERT_IS_OWNED(m) do { \
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if ((m)->m_qe.tqe_prev == NULL) \
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PANIC("mutex is not on list"); \
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} while (0)
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#define _MUTEX_ASSERT_NOT_OWNED(m) do { \
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if (((m)->m_qe.tqe_prev != NULL) || \
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((m)->m_qe.tqe_next != NULL)) \
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PANIC("mutex is on list"); \
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} while (0)
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#else
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#define _MUTEX_INIT_LINK(m)
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#define _MUTEX_ASSERT_IS_OWNED(m)
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#define _MUTEX_ASSERT_NOT_OWNED(m)
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#endif
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/*
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* Prototypes
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*/
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static inline int mutex_self_trylock(pthread_mutex_t);
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static inline int mutex_self_lock(pthread_mutex_t);
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static inline int mutex_unlock_common(pthread_mutex_t *, int);
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static void mutex_priority_adjust(pthread_mutex_t);
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static void mutex_rescan_owned (pthread_t, pthread_mutex_t);
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static inline pthread_t mutex_queue_deq(pthread_mutex_t);
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static inline void mutex_queue_remove(pthread_mutex_t, pthread_t);
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static inline void mutex_queue_enq(pthread_mutex_t, pthread_t);
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static spinlock_t static_init_lock = _SPINLOCK_INITIALIZER;
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/* Reinitialize a mutex to defaults. */
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int
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_mutex_reinit(pthread_mutex_t * mutex)
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{
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int ret = 0;
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if (mutex == NULL)
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ret = EINVAL;
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else if (*mutex == NULL)
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ret = pthread_mutex_init(mutex, NULL);
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else {
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/*
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* Initialize the mutex structure:
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*/
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(*mutex)->m_type = PTHREAD_MUTEX_DEFAULT;
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(*mutex)->m_protocol = PTHREAD_PRIO_NONE;
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TAILQ_INIT(&(*mutex)->m_queue);
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(*mutex)->m_owner = NULL;
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(*mutex)->m_data.m_count = 0;
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(*mutex)->m_flags = MUTEX_FLAGS_INITED;
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(*mutex)->m_refcount = 0;
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(*mutex)->m_prio = 0;
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(*mutex)->m_saved_prio = 0;
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_MUTEX_INIT_LINK(*mutex);
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memset(&(*mutex)->lock, 0, sizeof((*mutex)->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_mutex_init(pthread_mutex_t * mutex,
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const pthread_mutexattr_t * mutex_attr)
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{
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enum pthread_mutextype type;
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int protocol;
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int ceiling;
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pthread_mutex_t pmutex;
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int ret = 0;
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if (mutex == NULL)
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ret = EINVAL;
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/* Check if default mutex attributes: */
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else if (mutex_attr == NULL || *mutex_attr == NULL) {
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/* Default to a (error checking) POSIX mutex: */
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type = PTHREAD_MUTEX_ERRORCHECK;
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protocol = PTHREAD_PRIO_NONE;
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ceiling = PTHREAD_MAX_PRIORITY;
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}
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/* Check mutex type: */
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else if (((*mutex_attr)->m_type < PTHREAD_MUTEX_ERRORCHECK) ||
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((*mutex_attr)->m_type >= MUTEX_TYPE_MAX))
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/* Return an invalid argument error: */
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ret = EINVAL;
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/* Check mutex protocol: */
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else if (((*mutex_attr)->m_protocol < PTHREAD_PRIO_NONE) ||
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((*mutex_attr)->m_protocol > PTHREAD_MUTEX_RECURSIVE))
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/* Return an invalid argument error: */
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ret = EINVAL;
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else {
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/* Use the requested mutex type and protocol: */
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type = (*mutex_attr)->m_type;
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protocol = (*mutex_attr)->m_protocol;
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ceiling = (*mutex_attr)->m_ceiling;
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}
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/* Check no errors so far: */
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if (ret == 0) {
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if ((pmutex = (pthread_mutex_t)
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malloc(sizeof(struct pthread_mutex))) == NULL)
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ret = ENOMEM;
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else {
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/* Reset the mutex flags: */
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pmutex->m_flags = 0;
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/* Process according to mutex type: */
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switch (type) {
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/* case PTHREAD_MUTEX_DEFAULT: */
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case PTHREAD_MUTEX_ERRORCHECK:
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case PTHREAD_MUTEX_NORMAL:
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/* Nothing to do here. */
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break;
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/* Single UNIX Spec 2 recursive mutex: */
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case PTHREAD_MUTEX_RECURSIVE:
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/* Reset the mutex count: */
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pmutex->m_data.m_count = 0;
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break;
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/* Trap invalid mutex types: */
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default:
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/* Return an invalid argument error: */
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ret = EINVAL;
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break;
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}
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if (ret == 0) {
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/* Initialise the rest of the mutex: */
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TAILQ_INIT(&pmutex->m_queue);
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pmutex->m_flags |= MUTEX_FLAGS_INITED;
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pmutex->m_owner = NULL;
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pmutex->m_type = type;
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pmutex->m_protocol = protocol;
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pmutex->m_refcount = 0;
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if (protocol == PTHREAD_PRIO_PROTECT)
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pmutex->m_prio = ceiling;
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else
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pmutex->m_prio = 0;
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pmutex->m_saved_prio = 0;
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_MUTEX_INIT_LINK(pmutex);
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memset(&pmutex->lock, 0, sizeof(pmutex->lock));
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*mutex = pmutex;
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} else {
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free(pmutex);
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*mutex = NULL;
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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(ret);
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}
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int
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pthread_mutex_destroy(pthread_mutex_t * mutex)
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{
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int ret = 0;
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if (mutex == NULL || *mutex == NULL)
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ret = EINVAL;
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else {
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/* Lock the mutex structure: */
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_SPINLOCK(&(*mutex)->lock);
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/*
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* Check to see if this mutex is in use:
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*/
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if (((*mutex)->m_owner != NULL) ||
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(TAILQ_FIRST(&(*mutex)->m_queue) != NULL) ||
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((*mutex)->m_refcount != 0)) {
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ret = EBUSY;
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/* Unlock the mutex structure: */
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_SPINUNLOCK(&(*mutex)->lock);
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}
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else {
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/*
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* Free the memory allocated for the mutex
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* structure:
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*/
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_MUTEX_ASSERT_NOT_OWNED(*mutex);
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free(*mutex);
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/*
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* Leave the caller's pointer NULL now that
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* the mutex has been destroyed:
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*/
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*mutex = NULL;
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}
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}
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/* Return the completion status: */
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return (ret);
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}
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static int
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init_static (pthread_mutex_t *mutex)
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{
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int ret;
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_SPINLOCK(&static_init_lock);
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if (*mutex == NULL)
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ret = pthread_mutex_init(mutex, NULL);
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else
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ret = 0;
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_SPINUNLOCK(&static_init_lock);
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return(ret);
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}
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int
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pthread_mutex_trylock(pthread_mutex_t * mutex)
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{
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int ret = 0;
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if (mutex == NULL)
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ret = EINVAL;
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/*
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* If the mutex is statically initialized, perform the dynamic
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* initialization:
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*/
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else if (*mutex != NULL || (ret = init_static(mutex)) == 0) {
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/*
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* Defer signals to protect the scheduling queues from
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* access by the signal handler:
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*/
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_thread_kern_sig_defer();
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/* Lock the mutex structure: */
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_SPINLOCK(&(*mutex)->lock);
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/*
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* If the mutex was statically allocated, properly
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* initialize the tail queue.
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*/
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if (((*mutex)->m_flags & MUTEX_FLAGS_INITED) == 0) {
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TAILQ_INIT(&(*mutex)->m_queue);
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_MUTEX_INIT_LINK(*mutex);
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(*mutex)->m_flags |= MUTEX_FLAGS_INITED;
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}
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/* Process according to mutex type: */
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switch ((*mutex)->m_protocol) {
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/* Default POSIX mutex: */
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case PTHREAD_PRIO_NONE:
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/* Check if this mutex is not locked: */
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if ((*mutex)->m_owner == NULL) {
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/* Lock the mutex for the running thread: */
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(*mutex)->m_owner = _thread_run;
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/* Add to the list of owned mutexes: */
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_MUTEX_ASSERT_NOT_OWNED(*mutex);
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TAILQ_INSERT_TAIL(&_thread_run->mutexq,
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(*mutex), m_qe);
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} else if ((*mutex)->m_owner == _thread_run)
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ret = mutex_self_trylock(*mutex);
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else
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/* Return a busy error: */
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ret = EBUSY;
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break;
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/* POSIX priority inheritence mutex: */
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case PTHREAD_PRIO_INHERIT:
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/* Check if this mutex is not locked: */
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if ((*mutex)->m_owner == NULL) {
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/* Lock the mutex for the running thread: */
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(*mutex)->m_owner = _thread_run;
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/* Track number of priority mutexes owned: */
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_thread_run->priority_mutex_count++;
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/*
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* The mutex takes on the attributes of the
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* running thread when there are no waiters.
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*/
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(*mutex)->m_prio = _thread_run->active_priority;
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(*mutex)->m_saved_prio =
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_thread_run->inherited_priority;
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/* Add to the list of owned mutexes: */
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_MUTEX_ASSERT_NOT_OWNED(*mutex);
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TAILQ_INSERT_TAIL(&_thread_run->mutexq,
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(*mutex), m_qe);
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} else if ((*mutex)->m_owner == _thread_run)
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ret = mutex_self_trylock(*mutex);
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else
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/* Return a busy error: */
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ret = EBUSY;
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break;
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/* POSIX priority protection mutex: */
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case PTHREAD_PRIO_PROTECT:
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/* Check for a priority ceiling violation: */
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if (_thread_run->active_priority > (*mutex)->m_prio)
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ret = EINVAL;
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/* Check if this mutex is not locked: */
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else if ((*mutex)->m_owner == NULL) {
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/* Lock the mutex for the running thread: */
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(*mutex)->m_owner = _thread_run;
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/* Track number of priority mutexes owned: */
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_thread_run->priority_mutex_count++;
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/*
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* The running thread inherits the ceiling
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* priority of the mutex and executes at that
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* priority.
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*/
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_thread_run->active_priority = (*mutex)->m_prio;
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(*mutex)->m_saved_prio =
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_thread_run->inherited_priority;
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_thread_run->inherited_priority =
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(*mutex)->m_prio;
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/* Add to the list of owned mutexes: */
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_MUTEX_ASSERT_NOT_OWNED(*mutex);
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TAILQ_INSERT_TAIL(&_thread_run->mutexq,
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(*mutex), m_qe);
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} else if ((*mutex)->m_owner == _thread_run)
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ret = mutex_self_trylock(*mutex);
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else
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/* Return a busy error: */
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ret = EBUSY;
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break;
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/* Trap invalid mutex types: */
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default:
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/* Return an invalid argument error: */
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ret = EINVAL;
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break;
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}
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/* Unlock the mutex structure: */
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_SPINUNLOCK(&(*mutex)->lock);
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/*
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* Undefer and handle pending signals, yielding if
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* necessary:
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*/
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_thread_kern_sig_undefer();
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}
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/* Return the completion status: */
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return (ret);
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}
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int
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pthread_mutex_lock(pthread_mutex_t * mutex)
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{
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int ret = 0;
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if (mutex == NULL)
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ret = EINVAL;
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/*
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* If the mutex is statically initialized, perform the dynamic
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* initialization:
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*/
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else if (*mutex != NULL || (ret = init_static(mutex)) == 0) {
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/*
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* Defer signals to protect the scheduling queues from
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* access by the signal handler:
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*/
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_thread_kern_sig_defer();
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/* Lock the mutex structure: */
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_SPINLOCK(&(*mutex)->lock);
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/*
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* If the mutex was statically allocated, properly
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* initialize the tail queue.
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*/
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if (((*mutex)->m_flags & MUTEX_FLAGS_INITED) == 0) {
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TAILQ_INIT(&(*mutex)->m_queue);
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(*mutex)->m_flags |= MUTEX_FLAGS_INITED;
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_MUTEX_INIT_LINK(*mutex);
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}
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/* Process according to mutex type: */
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switch ((*mutex)->m_protocol) {
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/* Default POSIX mutex: */
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case PTHREAD_PRIO_NONE:
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if ((*mutex)->m_owner == NULL) {
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/* Lock the mutex for this thread: */
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(*mutex)->m_owner = _thread_run;
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/* Add to the list of owned mutexes: */
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_MUTEX_ASSERT_NOT_OWNED(*mutex);
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TAILQ_INSERT_TAIL(&_thread_run->mutexq,
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(*mutex), m_qe);
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} else if ((*mutex)->m_owner == _thread_run)
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ret = mutex_self_lock(*mutex);
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else {
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/*
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* Join the queue of threads waiting to lock
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* the mutex:
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*/
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mutex_queue_enq(*mutex, _thread_run);
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/*
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* Keep a pointer to the mutex this thread
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* is waiting on:
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*/
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_thread_run->data.mutex = *mutex;
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/*
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* Unlock the mutex structure and schedule the
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* next thread:
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*/
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_thread_kern_sched_state_unlock(PS_MUTEX_WAIT,
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&(*mutex)->lock, __FILE__, __LINE__);
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/* Lock the mutex structure again: */
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_SPINLOCK(&(*mutex)->lock);
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}
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break;
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/* POSIX priority inheritence mutex: */
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case PTHREAD_PRIO_INHERIT:
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/* Check if this mutex is not locked: */
|
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if ((*mutex)->m_owner == NULL) {
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/* Lock the mutex for this thread: */
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(*mutex)->m_owner = _thread_run;
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|
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/* Track number of priority mutexes owned: */
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_thread_run->priority_mutex_count++;
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/*
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* The mutex takes on attributes of the
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* running thread when there are no waiters.
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*/
|
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(*mutex)->m_prio = _thread_run->active_priority;
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(*mutex)->m_saved_prio =
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_thread_run->inherited_priority;
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_thread_run->inherited_priority =
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(*mutex)->m_prio;
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/* Add to the list of owned mutexes: */
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_MUTEX_ASSERT_NOT_OWNED(*mutex);
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TAILQ_INSERT_TAIL(&_thread_run->mutexq,
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(*mutex), m_qe);
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} else if ((*mutex)->m_owner == _thread_run)
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ret = mutex_self_lock(*mutex);
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else {
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/*
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* Join the queue of threads waiting to lock
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* the mutex:
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*/
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mutex_queue_enq(*mutex, _thread_run);
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/*
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* Keep a pointer to the mutex this thread
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* is waiting on:
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*/
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_thread_run->data.mutex = *mutex;
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if (_thread_run->active_priority >
|
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(*mutex)->m_prio)
|
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/* Adjust priorities: */
|
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mutex_priority_adjust(*mutex);
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|
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/*
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* Unlock the mutex structure and schedule the
|
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* next thread:
|
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*/
|
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_thread_kern_sched_state_unlock(PS_MUTEX_WAIT,
|
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&(*mutex)->lock, __FILE__, __LINE__);
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|
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/* Lock the mutex structure again: */
|
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_SPINLOCK(&(*mutex)->lock);
|
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}
|
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break;
|
|
|
|
/* POSIX priority protection mutex: */
|
|
case PTHREAD_PRIO_PROTECT:
|
|
/* Check for a priority ceiling violation: */
|
|
if (_thread_run->active_priority > (*mutex)->m_prio)
|
|
ret = EINVAL;
|
|
|
|
/* Check if this mutex is not locked: */
|
|
else if ((*mutex)->m_owner == NULL) {
|
|
/*
|
|
* Lock the mutex for the running
|
|
* thread:
|
|
*/
|
|
(*mutex)->m_owner = _thread_run;
|
|
|
|
/* Track number of priority mutexes owned: */
|
|
_thread_run->priority_mutex_count++;
|
|
|
|
/*
|
|
* The running thread inherits the ceiling
|
|
* priority of the mutex and executes at that
|
|
* priority:
|
|
*/
|
|
_thread_run->active_priority = (*mutex)->m_prio;
|
|
(*mutex)->m_saved_prio =
|
|
_thread_run->inherited_priority;
|
|
_thread_run->inherited_priority =
|
|
(*mutex)->m_prio;
|
|
|
|
/* Add to the list of owned mutexes: */
|
|
_MUTEX_ASSERT_NOT_OWNED(*mutex);
|
|
TAILQ_INSERT_TAIL(&_thread_run->mutexq,
|
|
(*mutex), m_qe);
|
|
} else if ((*mutex)->m_owner == _thread_run)
|
|
ret = mutex_self_lock(*mutex);
|
|
else {
|
|
/*
|
|
* Join the queue of threads waiting to lock
|
|
* the mutex:
|
|
*/
|
|
mutex_queue_enq(*mutex, _thread_run);
|
|
|
|
/*
|
|
* Keep a pointer to the mutex this thread
|
|
* is waiting on:
|
|
*/
|
|
_thread_run->data.mutex = *mutex;
|
|
|
|
/* Clear any previous error: */
|
|
_thread_run->error = 0;
|
|
|
|
/*
|
|
* Unlock the mutex structure and schedule the
|
|
* next thread:
|
|
*/
|
|
_thread_kern_sched_state_unlock(PS_MUTEX_WAIT,
|
|
&(*mutex)->lock, __FILE__, __LINE__);
|
|
|
|
/* Lock the mutex structure again: */
|
|
_SPINLOCK(&(*mutex)->lock);
|
|
|
|
/*
|
|
* The threads priority may have changed while
|
|
* waiting for the mutex causing a ceiling
|
|
* violation.
|
|
*/
|
|
ret = _thread_run->error;
|
|
_thread_run->error = 0;
|
|
}
|
|
break;
|
|
|
|
/* Trap invalid mutex types: */
|
|
default:
|
|
/* Return an invalid argument error: */
|
|
ret = EINVAL;
|
|
break;
|
|
}
|
|
|
|
/* Unlock the mutex structure: */
|
|
_SPINUNLOCK(&(*mutex)->lock);
|
|
|
|
/*
|
|
* Undefer and handle pending signals, yielding if
|
|
* necessary:
|
|
*/
|
|
_thread_kern_sig_undefer();
|
|
}
|
|
|
|
/* Return the completion status: */
|
|
return (ret);
|
|
}
|
|
|
|
int
|
|
pthread_mutex_unlock(pthread_mutex_t * mutex)
|
|
{
|
|
return (mutex_unlock_common(mutex, /* add reference */ 0));
|
|
}
|
|
|
|
int
|
|
_mutex_cv_unlock(pthread_mutex_t * mutex)
|
|
{
|
|
return (mutex_unlock_common(mutex, /* add reference */ 1));
|
|
}
|
|
|
|
int
|
|
_mutex_cv_lock(pthread_mutex_t * mutex)
|
|
{
|
|
int ret;
|
|
if ((ret = pthread_mutex_lock(mutex)) == 0)
|
|
(*mutex)->m_refcount--;
|
|
return (ret);
|
|
}
|
|
|
|
static inline int
|
|
mutex_self_trylock(pthread_mutex_t mutex)
|
|
{
|
|
int ret = 0;
|
|
|
|
switch (mutex->m_type) {
|
|
|
|
/* case PTHREAD_MUTEX_DEFAULT: */
|
|
case PTHREAD_MUTEX_ERRORCHECK:
|
|
case PTHREAD_MUTEX_NORMAL:
|
|
/*
|
|
* POSIX specifies that mutexes should return EDEADLK if a
|
|
* recursive lock is detected.
|
|
*/
|
|
ret = EBUSY;
|
|
break;
|
|
|
|
case PTHREAD_MUTEX_RECURSIVE:
|
|
/* Increment the lock count: */
|
|
mutex->m_data.m_count++;
|
|
break;
|
|
|
|
default:
|
|
/* Trap invalid mutex types; */
|
|
ret = EINVAL;
|
|
}
|
|
|
|
return(ret);
|
|
}
|
|
|
|
static inline int
|
|
mutex_self_lock(pthread_mutex_t mutex)
|
|
{
|
|
int ret = 0;
|
|
|
|
switch (mutex->m_type) {
|
|
/* case PTHREAD_MUTEX_DEFAULT: */
|
|
case PTHREAD_MUTEX_ERRORCHECK:
|
|
/*
|
|
* POSIX specifies that mutexes should return EDEADLK if a
|
|
* recursive lock is detected.
|
|
*/
|
|
ret = EDEADLK;
|
|
break;
|
|
|
|
case PTHREAD_MUTEX_NORMAL:
|
|
/*
|
|
* What SS2 define as a 'normal' mutex. Intentionally
|
|
* deadlock on attempts to get a lock you already own.
|
|
*/
|
|
_thread_kern_sched_state_unlock(PS_DEADLOCK,
|
|
&mutex->lock, __FILE__, __LINE__);
|
|
break;
|
|
|
|
case PTHREAD_MUTEX_RECURSIVE:
|
|
/* Increment the lock count: */
|
|
mutex->m_data.m_count++;
|
|
break;
|
|
|
|
default:
|
|
/* Trap invalid mutex types; */
|
|
ret = EINVAL;
|
|
}
|
|
|
|
return(ret);
|
|
}
|
|
|
|
static inline int
|
|
mutex_unlock_common(pthread_mutex_t * mutex, int add_reference)
|
|
{
|
|
int ret = 0;
|
|
|
|
if (mutex == NULL || *mutex == NULL) {
|
|
ret = EINVAL;
|
|
} else {
|
|
/*
|
|
* Defer signals to protect the scheduling queues from
|
|
* access by the signal handler:
|
|
*/
|
|
_thread_kern_sig_defer();
|
|
|
|
/* Lock the mutex structure: */
|
|
_SPINLOCK(&(*mutex)->lock);
|
|
|
|
/* Process according to mutex type: */
|
|
switch ((*mutex)->m_protocol) {
|
|
/* Default POSIX mutex: */
|
|
case PTHREAD_PRIO_NONE:
|
|
/*
|
|
* Check if the running thread is not the owner of the
|
|
* mutex:
|
|
*/
|
|
if ((*mutex)->m_owner != _thread_run) {
|
|
/*
|
|
* Return an invalid argument error for no
|
|
* owner and a permission error otherwise:
|
|
*/
|
|
ret = (*mutex)->m_owner == NULL ? EINVAL : EPERM;
|
|
}
|
|
else if (((*mutex)->m_type == PTHREAD_MUTEX_RECURSIVE) &&
|
|
((*mutex)->m_data.m_count > 1)) {
|
|
/* Decrement the count: */
|
|
(*mutex)->m_data.m_count--;
|
|
} else {
|
|
/*
|
|
* Clear the count in case this is recursive
|
|
* mutex.
|
|
*/
|
|
(*mutex)->m_data.m_count = 0;
|
|
|
|
/* Remove the mutex from the threads queue. */
|
|
_MUTEX_ASSERT_IS_OWNED(*mutex);
|
|
TAILQ_REMOVE(&(*mutex)->m_owner->mutexq,
|
|
(*mutex), m_qe);
|
|
_MUTEX_INIT_LINK(*mutex);
|
|
|
|
/*
|
|
* Get the next thread from the queue of
|
|
* threads waiting on the mutex:
|
|
*/
|
|
if (((*mutex)->m_owner =
|
|
mutex_queue_deq(*mutex)) != NULL) {
|
|
/*
|
|
* Allow the new owner of the mutex to
|
|
* run:
|
|
*/
|
|
PTHREAD_NEW_STATE((*mutex)->m_owner,
|
|
PS_RUNNING);
|
|
|
|
/*
|
|
* Add the mutex to the threads list of
|
|
* owned mutexes:
|
|
*/
|
|
TAILQ_INSERT_TAIL(&(*mutex)->m_owner->mutexq,
|
|
(*mutex), m_qe);
|
|
|
|
/*
|
|
* The owner is no longer waiting for
|
|
* this mutex:
|
|
*/
|
|
(*mutex)->m_owner->data.mutex = NULL;
|
|
}
|
|
}
|
|
break;
|
|
|
|
/* POSIX priority inheritence mutex: */
|
|
case PTHREAD_PRIO_INHERIT:
|
|
/*
|
|
* Check if the running thread is not the owner of the
|
|
* mutex:
|
|
*/
|
|
if ((*mutex)->m_owner != _thread_run) {
|
|
/*
|
|
* Return an invalid argument error for no
|
|
* owner and a permission error otherwise:
|
|
*/
|
|
ret = (*mutex)->m_owner == NULL ? EINVAL : EPERM;
|
|
}
|
|
else if (((*mutex)->m_type == PTHREAD_MUTEX_RECURSIVE) &&
|
|
((*mutex)->m_data.m_count > 1)) {
|
|
/* Decrement the count: */
|
|
(*mutex)->m_data.m_count--;
|
|
} else {
|
|
/*
|
|
* Clear the count in case this is recursive
|
|
* mutex.
|
|
*/
|
|
(*mutex)->m_data.m_count = 0;
|
|
|
|
/*
|
|
* Restore the threads inherited priority and
|
|
* recompute the active priority (being careful
|
|
* not to override changes in the threads base
|
|
* priority subsequent to locking the mutex).
|
|
*/
|
|
_thread_run->inherited_priority =
|
|
(*mutex)->m_saved_prio;
|
|
_thread_run->active_priority =
|
|
MAX(_thread_run->inherited_priority,
|
|
_thread_run->base_priority);
|
|
|
|
/*
|
|
* This thread now owns one less priority mutex.
|
|
*/
|
|
_thread_run->priority_mutex_count--;
|
|
|
|
/* Remove the mutex from the threads queue. */
|
|
_MUTEX_ASSERT_IS_OWNED(*mutex);
|
|
TAILQ_REMOVE(&(*mutex)->m_owner->mutexq,
|
|
(*mutex), m_qe);
|
|
_MUTEX_INIT_LINK(*mutex);
|
|
|
|
/*
|
|
* Get the next thread from the queue of threads
|
|
* waiting on the mutex:
|
|
*/
|
|
if (((*mutex)->m_owner =
|
|
mutex_queue_deq(*mutex)) == NULL)
|
|
/* This mutex has no priority. */
|
|
(*mutex)->m_prio = 0;
|
|
else {
|
|
/*
|
|
* Track number of priority mutexes owned:
|
|
*/
|
|
(*mutex)->m_owner->priority_mutex_count++;
|
|
|
|
/*
|
|
* Add the mutex to the threads list
|
|
* of owned mutexes:
|
|
*/
|
|
TAILQ_INSERT_TAIL(&(*mutex)->m_owner->mutexq,
|
|
(*mutex), m_qe);
|
|
|
|
/*
|
|
* The owner is no longer waiting for
|
|
* this mutex:
|
|
*/
|
|
(*mutex)->m_owner->data.mutex = NULL;
|
|
|
|
/*
|
|
* Set the priority of the mutex. Since
|
|
* our waiting threads are in descending
|
|
* priority order, the priority of the
|
|
* mutex becomes the active priority of
|
|
* the thread we just dequeued.
|
|
*/
|
|
(*mutex)->m_prio =
|
|
(*mutex)->m_owner->active_priority;
|
|
|
|
/*
|
|
* Save the owning threads inherited
|
|
* priority:
|
|
*/
|
|
(*mutex)->m_saved_prio =
|
|
(*mutex)->m_owner->inherited_priority;
|
|
|
|
/*
|
|
* The owning threads inherited priority
|
|
* now becomes his active priority (the
|
|
* priority of the mutex).
|
|
*/
|
|
(*mutex)->m_owner->inherited_priority =
|
|
(*mutex)->m_prio;
|
|
|
|
/*
|
|
* Allow the new owner of the mutex to
|
|
* run:
|
|
*/
|
|
PTHREAD_NEW_STATE((*mutex)->m_owner,
|
|
PS_RUNNING);
|
|
}
|
|
}
|
|
break;
|
|
|
|
/* POSIX priority ceiling mutex: */
|
|
case PTHREAD_PRIO_PROTECT:
|
|
/*
|
|
* Check if the running thread is not the owner of the
|
|
* mutex:
|
|
*/
|
|
if ((*mutex)->m_owner != _thread_run) {
|
|
/*
|
|
* Return an invalid argument error for no
|
|
* owner and a permission error otherwise:
|
|
*/
|
|
ret = (*mutex)->m_owner == NULL ? EINVAL : EPERM;
|
|
}
|
|
else if (((*mutex)->m_type == PTHREAD_MUTEX_RECURSIVE) &&
|
|
((*mutex)->m_data.m_count > 1)) {
|
|
/* Decrement the count: */
|
|
(*mutex)->m_data.m_count--;
|
|
} else {
|
|
/*
|
|
* Clear the count in case this is recursive
|
|
* mutex.
|
|
*/
|
|
(*mutex)->m_data.m_count = 0;
|
|
|
|
/*
|
|
* Restore the threads inherited priority and
|
|
* recompute the active priority (being careful
|
|
* not to override changes in the threads base
|
|
* priority subsequent to locking the mutex).
|
|
*/
|
|
_thread_run->inherited_priority =
|
|
(*mutex)->m_saved_prio;
|
|
_thread_run->active_priority =
|
|
MAX(_thread_run->inherited_priority,
|
|
_thread_run->base_priority);
|
|
|
|
/*
|
|
* This thread now owns one less priority mutex.
|
|
*/
|
|
_thread_run->priority_mutex_count--;
|
|
|
|
/* Remove the mutex from the threads queue. */
|
|
_MUTEX_ASSERT_IS_OWNED(*mutex);
|
|
TAILQ_REMOVE(&(*mutex)->m_owner->mutexq,
|
|
(*mutex), m_qe);
|
|
_MUTEX_INIT_LINK(*mutex);
|
|
|
|
/*
|
|
* Enter a loop to find a waiting thread whose
|
|
* active priority will not cause a ceiling
|
|
* violation:
|
|
*/
|
|
while ((((*mutex)->m_owner =
|
|
mutex_queue_deq(*mutex)) != NULL) &&
|
|
((*mutex)->m_owner->active_priority >
|
|
(*mutex)->m_prio)) {
|
|
/*
|
|
* Either the mutex ceiling priority
|
|
* been lowered and/or this threads
|
|
* priority has been raised subsequent
|
|
* to this thread being queued on the
|
|
* waiting list.
|
|
*/
|
|
(*mutex)->m_owner->error = EINVAL;
|
|
PTHREAD_NEW_STATE((*mutex)->m_owner,
|
|
PS_RUNNING);
|
|
/*
|
|
* The thread is no longer waiting for
|
|
* this mutex:
|
|
*/
|
|
(*mutex)->m_owner->data.mutex = NULL;
|
|
}
|
|
|
|
/* Check for a new owner: */
|
|
if ((*mutex)->m_owner != NULL) {
|
|
/*
|
|
* Track number of priority mutexes owned:
|
|
*/
|
|
(*mutex)->m_owner->priority_mutex_count++;
|
|
|
|
/*
|
|
* Add the mutex to the threads list
|
|
* of owned mutexes:
|
|
*/
|
|
TAILQ_INSERT_TAIL(&(*mutex)->m_owner->mutexq,
|
|
(*mutex), m_qe);
|
|
|
|
/*
|
|
* The owner is no longer waiting for
|
|
* this mutex:
|
|
*/
|
|
(*mutex)->m_owner->data.mutex = NULL;
|
|
|
|
/*
|
|
* Save the owning threads inherited
|
|
* priority:
|
|
*/
|
|
(*mutex)->m_saved_prio =
|
|
(*mutex)->m_owner->inherited_priority;
|
|
|
|
/*
|
|
* The owning thread inherits the
|
|
* ceiling priority of the mutex and
|
|
* executes at that priority:
|
|
*/
|
|
(*mutex)->m_owner->inherited_priority =
|
|
(*mutex)->m_prio;
|
|
(*mutex)->m_owner->active_priority =
|
|
(*mutex)->m_prio;
|
|
|
|
/*
|
|
* Allow the new owner of the mutex to
|
|
* run:
|
|
*/
|
|
PTHREAD_NEW_STATE((*mutex)->m_owner,
|
|
PS_RUNNING);
|
|
}
|
|
}
|
|
break;
|
|
|
|
/* Trap invalid mutex types: */
|
|
default:
|
|
/* Return an invalid argument error: */
|
|
ret = EINVAL;
|
|
break;
|
|
}
|
|
|
|
if ((ret == 0) && (add_reference != 0)) {
|
|
/* Increment the reference count: */
|
|
(*mutex)->m_refcount++;
|
|
}
|
|
|
|
/* Unlock the mutex structure: */
|
|
_SPINUNLOCK(&(*mutex)->lock);
|
|
|
|
/*
|
|
* Undefer and handle pending signals, yielding if
|
|
* necessary:
|
|
*/
|
|
_thread_kern_sig_undefer();
|
|
}
|
|
|
|
/* Return the completion status: */
|
|
return (ret);
|
|
}
|
|
|
|
|
|
/*
|
|
* This function is called when a change in base priority occurs for
|
|
* a thread that is holding or waiting for a priority protection or
|
|
* inheritence mutex. A change in a threads base priority can effect
|
|
* changes to active priorities of other threads and to the ordering
|
|
* of mutex locking by waiting threads.
|
|
*
|
|
* This must be called while thread scheduling is deferred.
|
|
*/
|
|
void
|
|
_mutex_notify_priochange(pthread_t pthread)
|
|
{
|
|
/* Adjust the priorites of any owned priority mutexes: */
|
|
if (pthread->priority_mutex_count > 0) {
|
|
/*
|
|
* Rescan the mutexes owned by this thread and correct
|
|
* their priorities to account for this threads change
|
|
* in priority. This has the side effect of changing
|
|
* the threads active priority.
|
|
*/
|
|
mutex_rescan_owned(pthread, /* rescan all owned */ NULL);
|
|
}
|
|
|
|
/*
|
|
* If this thread is waiting on a priority inheritence mutex,
|
|
* check for priority adjustments. A change in priority can
|
|
* also effect a ceiling violation(*) for a thread waiting on
|
|
* a priority protection mutex; we don't perform the check here
|
|
* as it is done in pthread_mutex_unlock.
|
|
*
|
|
* (*) It should be noted that a priority change to a thread
|
|
* _after_ taking and owning a priority ceiling mutex
|
|
* does not affect ownership of that mutex; the ceiling
|
|
* priority is only checked before mutex ownership occurs.
|
|
*/
|
|
if (pthread->state == PS_MUTEX_WAIT) {
|
|
/* Lock the mutex structure: */
|
|
_SPINLOCK(&pthread->data.mutex->lock);
|
|
|
|
/*
|
|
* Check to make sure this thread is still in the same state
|
|
* (the spinlock above can yield the CPU to another thread):
|
|
*/
|
|
if (pthread->state == PS_MUTEX_WAIT) {
|
|
/*
|
|
* Remove and reinsert this thread into the list of
|
|
* waiting threads to preserve decreasing priority
|
|
* order.
|
|
*/
|
|
mutex_queue_remove(pthread->data.mutex, pthread);
|
|
mutex_queue_enq(pthread->data.mutex, pthread);
|
|
|
|
if (pthread->data.mutex->m_protocol ==
|
|
PTHREAD_PRIO_INHERIT) {
|
|
/* Adjust priorities: */
|
|
mutex_priority_adjust(pthread->data.mutex);
|
|
}
|
|
}
|
|
|
|
/* Unlock the mutex structure: */
|
|
_SPINUNLOCK(&pthread->data.mutex->lock);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Called when a new thread is added to the mutex waiting queue or
|
|
* when a threads priority changes that is already in the mutex
|
|
* waiting queue.
|
|
*/
|
|
static void
|
|
mutex_priority_adjust(pthread_mutex_t mutex)
|
|
{
|
|
pthread_t pthread_next, pthread = mutex->m_owner;
|
|
int temp_prio;
|
|
pthread_mutex_t m = mutex;
|
|
|
|
/*
|
|
* Calculate the mutex priority as the maximum of the highest
|
|
* active priority of any waiting threads and the owning threads
|
|
* active priority(*).
|
|
*
|
|
* (*) Because the owning threads current active priority may
|
|
* reflect priority inherited from this mutex (and the mutex
|
|
* priority may have changed) we must recalculate the active
|
|
* priority based on the threads saved inherited priority
|
|
* and its base priority.
|
|
*/
|
|
pthread_next = TAILQ_FIRST(&m->m_queue); /* should never be NULL */
|
|
temp_prio = MAX(pthread_next->active_priority,
|
|
MAX(m->m_saved_prio, pthread->base_priority));
|
|
|
|
/* See if this mutex really needs adjusting: */
|
|
if (temp_prio == m->m_prio)
|
|
/* No need to propagate the priority: */
|
|
return;
|
|
|
|
/* Set new priority of the mutex: */
|
|
m->m_prio = temp_prio;
|
|
|
|
while (m != NULL) {
|
|
/*
|
|
* Save the threads priority before rescanning the
|
|
* owned mutexes:
|
|
*/
|
|
temp_prio = pthread->active_priority;
|
|
|
|
/*
|
|
* Fix the priorities for all the mutexes this thread has
|
|
* locked since taking this mutex. This also has a
|
|
* potential side-effect of changing the threads priority.
|
|
*/
|
|
mutex_rescan_owned(pthread, m);
|
|
|
|
/*
|
|
* If the thread is currently waiting on a mutex, check
|
|
* to see if the threads new priority has affected the
|
|
* priority of the mutex.
|
|
*/
|
|
if ((temp_prio != pthread->active_priority) &&
|
|
(pthread->state == PS_MUTEX_WAIT) &&
|
|
(pthread->data.mutex->m_protocol == PTHREAD_PRIO_INHERIT)) {
|
|
/* Grab the mutex this thread is waiting on: */
|
|
m = pthread->data.mutex;
|
|
|
|
/*
|
|
* The priority for this thread has changed. Remove
|
|
* and reinsert this thread into the list of waiting
|
|
* threads to preserve decreasing priority order.
|
|
*/
|
|
mutex_queue_remove(m, pthread);
|
|
mutex_queue_enq(m, pthread);
|
|
|
|
/* Grab the waiting thread with highest priority: */
|
|
pthread_next = TAILQ_FIRST(&m->m_queue);
|
|
|
|
/*
|
|
* Calculate the mutex priority as the maximum of the
|
|
* highest active priority of any waiting threads and
|
|
* the owning threads active priority.
|
|
*/
|
|
temp_prio = MAX(pthread_next->active_priority,
|
|
MAX(m->m_saved_prio, m->m_owner->base_priority));
|
|
|
|
if (temp_prio != m->m_prio) {
|
|
/*
|
|
* The priority needs to be propagated to the
|
|
* mutex this thread is waiting on and up to
|
|
* the owner of that mutex.
|
|
*/
|
|
m->m_prio = temp_prio;
|
|
pthread = m->m_owner;
|
|
}
|
|
else
|
|
/* We're done: */
|
|
m = NULL;
|
|
|
|
}
|
|
else
|
|
/* We're done: */
|
|
m = NULL;
|
|
}
|
|
}
|
|
|
|
static void
|
|
mutex_rescan_owned (pthread_t pthread, pthread_mutex_t mutex)
|
|
{
|
|
int active_prio, inherited_prio;
|
|
pthread_mutex_t m;
|
|
pthread_t pthread_next;
|
|
|
|
/*
|
|
* Start walking the mutexes the thread has taken since
|
|
* taking this mutex.
|
|
*/
|
|
if (mutex == NULL) {
|
|
/*
|
|
* A null mutex means start at the beginning of the owned
|
|
* mutex list.
|
|
*/
|
|
m = TAILQ_FIRST(&pthread->mutexq);
|
|
|
|
/* There is no inherited priority yet. */
|
|
inherited_prio = 0;
|
|
}
|
|
else {
|
|
/*
|
|
* The caller wants to start after a specific mutex. It
|
|
* is assumed that this mutex is a priority inheritence
|
|
* mutex and that its priority has been correctly
|
|
* calculated.
|
|
*/
|
|
m = TAILQ_NEXT(mutex, m_qe);
|
|
|
|
/* Start inheriting priority from the specified mutex. */
|
|
inherited_prio = mutex->m_prio;
|
|
}
|
|
active_prio = MAX(inherited_prio, pthread->base_priority);
|
|
|
|
while (m != NULL) {
|
|
/*
|
|
* We only want to deal with priority inheritence
|
|
* mutexes. This might be optimized by only placing
|
|
* priority inheritence mutexes into the owned mutex
|
|
* list, but it may prove to be useful having all
|
|
* owned mutexes in this list. Consider a thread
|
|
* exiting while holding mutexes...
|
|
*/
|
|
if (m->m_protocol == PTHREAD_PRIO_INHERIT) {
|
|
/*
|
|
* Fix the owners saved (inherited) priority to
|
|
* reflect the priority of the previous mutex.
|
|
*/
|
|
m->m_saved_prio = inherited_prio;
|
|
|
|
if ((pthread_next = TAILQ_FIRST(&m->m_queue)) != NULL)
|
|
/* Recalculate the priority of the mutex: */
|
|
m->m_prio = MAX(active_prio,
|
|
pthread_next->active_priority);
|
|
else
|
|
m->m_prio = active_prio;
|
|
|
|
/* Recalculate new inherited and active priorities: */
|
|
inherited_prio = m->m_prio;
|
|
active_prio = MAX(m->m_prio, pthread->base_priority);
|
|
}
|
|
|
|
/* Advance to the next mutex owned by this thread: */
|
|
m = TAILQ_NEXT(m, m_qe);
|
|
}
|
|
|
|
/*
|
|
* Fix the threads inherited priority and recalculate its
|
|
* active priority.
|
|
*/
|
|
pthread->inherited_priority = inherited_prio;
|
|
active_prio = MAX(inherited_prio, pthread->base_priority);
|
|
|
|
if (active_prio != pthread->active_priority) {
|
|
/*
|
|
* If this thread is in the priority queue, it must be
|
|
* removed and reinserted for its new priority.
|
|
*/
|
|
if (pthread->flags & PTHREAD_FLAGS_IN_PRIOQ) {
|
|
/*
|
|
* Remove the thread from the priority queue
|
|
* before changing its priority:
|
|
*/
|
|
PTHREAD_PRIOQ_REMOVE(pthread);
|
|
|
|
/*
|
|
* POSIX states that if the priority is being
|
|
* lowered, the thread must be inserted at the
|
|
* head of the queue for its priority if it owns
|
|
* any priority protection or inheritence mutexes.
|
|
*/
|
|
if ((active_prio < pthread->active_priority) &&
|
|
(pthread->priority_mutex_count > 0)) {
|
|
/* Set the new active priority. */
|
|
pthread->active_priority = active_prio;
|
|
|
|
PTHREAD_PRIOQ_INSERT_HEAD(pthread);
|
|
}
|
|
else {
|
|
/* Set the new active priority. */
|
|
pthread->active_priority = active_prio;
|
|
|
|
PTHREAD_PRIOQ_INSERT_TAIL(pthread);
|
|
}
|
|
}
|
|
else {
|
|
/* Set the new active priority. */
|
|
pthread->active_priority = active_prio;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Dequeue a waiting thread from the head of a mutex queue in descending
|
|
* priority order.
|
|
*/
|
|
static inline pthread_t
|
|
mutex_queue_deq(pthread_mutex_t mutex)
|
|
{
|
|
pthread_t pthread;
|
|
|
|
if ((pthread = TAILQ_FIRST(&mutex->m_queue)) != NULL)
|
|
TAILQ_REMOVE(&mutex->m_queue, pthread, qe);
|
|
|
|
return(pthread);
|
|
}
|
|
|
|
/*
|
|
* Remove a waiting thread from a mutex queue in descending priority order.
|
|
*/
|
|
static inline void
|
|
mutex_queue_remove(pthread_mutex_t mutex, pthread_t pthread)
|
|
{
|
|
TAILQ_REMOVE(&mutex->m_queue, pthread, qe);
|
|
}
|
|
|
|
/*
|
|
* Enqueue a waiting thread to a queue in descending priority order.
|
|
*/
|
|
static inline void
|
|
mutex_queue_enq(pthread_mutex_t mutex, pthread_t pthread)
|
|
{
|
|
pthread_t tid = TAILQ_LAST(&mutex->m_queue, mutex_head);
|
|
|
|
/*
|
|
* 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(&mutex->m_queue, pthread, qe);
|
|
else {
|
|
tid = TAILQ_FIRST(&mutex->m_queue);
|
|
while (pthread->active_priority <= tid->active_priority)
|
|
tid = TAILQ_NEXT(tid, qe);
|
|
TAILQ_INSERT_BEFORE(tid, pthread, qe);
|
|
}
|
|
}
|
|
|
|
#endif
|