415 lines
10 KiB
C
415 lines
10 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 REGENTS 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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*/
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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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#ifdef _THREAD_SAFE
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#include <pthread.h>
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#include "pthread_private.h"
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static spinlock_t static_init_lock = _SPINLOCK_INITIALIZER;
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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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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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} else {
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/* Check if default mutex attributes: */
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if (mutex_attr == NULL || *mutex_attr == NULL)
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/* Default to a fast mutex: */
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type = PTHREAD_MUTEX_DEFAULT;
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else if ((*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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else
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/* Use the requested mutex type: */
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type = (*mutex_attr)->m_type;
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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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/* Fast mutex: */
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case PTHREAD_MUTEX_DEFAULT:
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case PTHREAD_MUTEX_NORMAL:
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case PTHREAD_MUTEX_ERRORCHECK:
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/* Nothing to do here. */
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break;
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/* Counting 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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_thread_queue_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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memset(&pmutex->lock, 0,
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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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}
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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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* Free the memory allocated for the mutex
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* structure:
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*/
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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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/* 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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/* Lock the mutex structure: */
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_SPINLOCK(&(*mutex)->lock);
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/* Process according to mutex type: */
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switch ((*mutex)->m_type) {
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/* Fast mutex: */
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case PTHREAD_MUTEX_NORMAL:
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case PTHREAD_MUTEX_DEFAULT:
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case PTHREAD_MUTEX_ERRORCHECK:
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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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} else {
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/* Return a busy error: */
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ret = EBUSY;
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}
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break;
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/* Counting mutex: */
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case PTHREAD_MUTEX_RECURSIVE:
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/* Check if this mutex is locked: */
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if ((*mutex)->m_owner != NULL) {
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/*
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* Check if the mutex is locked by the running
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* thread:
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*/
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if ((*mutex)->m_owner == _thread_run) {
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/* Increment the lock count: */
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(*mutex)->m_data.m_count++;
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} else {
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/* Return a busy error: */
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ret = EBUSY;
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}
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} else {
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/* Lock the mutex for the running thread: */
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(*mutex)->m_owner = _thread_run;
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}
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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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/* 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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/* Lock the mutex structure: */
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_SPINLOCK(&(*mutex)->lock);
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/* Process according to mutex type: */
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switch ((*mutex)->m_type) {
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/* What SS2 define as a 'normal' mutex. This has to deadlock
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on attempts to get a lock you already own. */
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case PTHREAD_MUTEX_NORMAL:
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if ((*mutex)->m_owner == _thread_run) {
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/* Intetionally deadlock */
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for (;;)
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_thread_kern_sched_state(PS_MUTEX_WAIT, __FILE__, __LINE__);
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}
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goto COMMON_LOCK;
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/* Return error (not OK) on attempting to re-lock */
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case PTHREAD_MUTEX_ERRORCHECK:
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if ((*mutex)->m_owner == _thread_run) {
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ret = EDEADLK;
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break;
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}
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/* Fast mutexes do not check for any error conditions: */
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case PTHREAD_MUTEX_DEFAULT:
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COMMON_LOCK:
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/*
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* Enter a loop to wait for the mutex to be locked by the
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* current thread:
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*/
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while ((*mutex)->m_owner != _thread_run) {
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/* Check if the 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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} 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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_thread_queue_enq(&(*mutex)->m_queue, _thread_run);
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/* Wait for the mutex: */
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_thread_kern_sched_state_unlock(
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PS_MUTEX_WAIT, &(*mutex)->lock,
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__FILE__, __LINE__);
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/* Lock the mutex again: */
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_SPINLOCK(&(*mutex)->lock);
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}
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}
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break;
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/* Counting mutex: */
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case PTHREAD_MUTEX_RECURSIVE:
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/*
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* Enter a loop to wait for the mutex to be locked by the
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* current thread:
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*/
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while ((*mutex)->m_owner != _thread_run) {
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/* Check if the 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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/* Reset the lock count for this mutex: */
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(*mutex)->m_data.m_count = 0;
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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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_thread_queue_enq(&(*mutex)->m_queue, _thread_run);
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/* Wait for the mutex: */
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_thread_kern_sched_state_unlock(
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PS_MUTEX_WAIT, &(*mutex)->lock,
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__FILE__, __LINE__);
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/* Lock the mutex again: */
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_SPINLOCK(&(*mutex)->lock);
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}
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}
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/* Increment the lock count for this mutex: */
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(*mutex)->m_data.m_count++;
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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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/* 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_unlock(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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/* Process according to mutex type: */
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switch ((*mutex)->m_type) {
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/* Default & normal mutexes do not really need to check for
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any error conditions: */
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case PTHREAD_MUTEX_NORMAL:
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case PTHREAD_MUTEX_DEFAULT:
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case PTHREAD_MUTEX_ERRORCHECK:
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/* Check if the running thread is not the owner of the mutex: */
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if ((*mutex)->m_owner != _thread_run) {
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/* Return an invalid argument error: */
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ret = (*mutex)->m_owner ? EPERM : EINVAL;
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}
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/*
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* Get the next thread from the queue of threads waiting on
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* the mutex:
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*/
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else if (((*mutex)->m_owner = _thread_queue_deq(&(*mutex)->m_queue)) != NULL) {
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/* Allow the new owner of the mutex to run: */
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PTHREAD_NEW_STATE((*mutex)->m_owner,PS_RUNNING);
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}
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break;
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/* Counting mutex: */
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case PTHREAD_MUTEX_RECURSIVE:
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/* Check if the running thread is not the owner of the mutex: */
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if ((*mutex)->m_owner != _thread_run) {
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/* Return an invalid argument error: */
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ret = EINVAL;
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}
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/* Check if there are still counts: */
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else if ((*mutex)->m_data.m_count > 1) {
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/* Decrement the count: */
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(*mutex)->m_data.m_count--;
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} else {
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(*mutex)->m_data.m_count = 0;
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/*
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* Get the next thread from the queue of threads waiting on
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* the mutex:
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*/
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if (((*mutex)->m_owner = _thread_queue_deq(&(*mutex)->m_queue)) != NULL) {
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/* Allow the new owner of the mutex to run: */
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PTHREAD_NEW_STATE((*mutex)->m_owner,PS_RUNNING);
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}
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}
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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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/* Return the completion status: */
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return (ret);
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}
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#endif
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