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-rw-r--r--lib/libpthread/thread/thr_mutex.c360
1 files changed, 360 insertions, 0 deletions
diff --git a/lib/libpthread/thread/thr_mutex.c b/lib/libpthread/thread/thr_mutex.c
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+++ b/lib/libpthread/thread/thr_mutex.c
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+/*
+ * Copyright (c) 1995 John Birrell <jb@cimlogic.com.au>.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by John Birrell.
+ * 4. Neither the name of the author nor the names of any co-contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ */
+#include <stdlib.h>
+#include <errno.h>
+#ifdef _THREAD_SAFE
+#include <pthread.h>
+#include "pthread_private.h"
+
+int
+pthread_mutex_init(pthread_mutex_t * mutex,
+ const pthread_mutexattr_t * mutex_attr)
+{
+ enum pthread_mutextype type;
+ int ret = 0;
+ int status;
+
+ /* Check if the mutex attributes specify some mutex other than fast: */
+ if (mutex_attr != NULL && mutex_attr->m_type != MUTEX_TYPE_FAST) {
+ /* Check if the mutex type is out of range: */
+ if (mutex_attr->m_type >= MUTEX_TYPE_MAX) {
+ /* Return an invalid argument error: */
+ _thread_seterrno(_thread_run, EINVAL);
+ ret = -1;
+ } else {
+ /* Use the requested mutex type: */
+ type = mutex_attr->m_type;
+ }
+ } else {
+ /* Default to a fast mutex: */
+ type = MUTEX_TYPE_FAST;
+ }
+
+ /* Check no errors so far: */
+ if (ret == 0) {
+ /* Reset the mutex flags: */
+ mutex->m_flags = 0;
+
+ /* Block signals: */
+ _thread_kern_sig_block(&status);
+
+ /* Process according to mutex type: */
+ switch (type) {
+ /* Fast mutex: */
+ case MUTEX_TYPE_FAST:
+ /* Nothing to do here. */
+ break;
+
+ /* Counting mutex: */
+ case MUTEX_TYPE_COUNTING_FAST:
+ /* Reset the mutex count: */
+ mutex->m_data.m_count = 0;
+ break;
+
+ /* Trap invalid mutex types: */
+ default:
+ /* Return an invalid argument error: */
+ _thread_seterrno(_thread_run, EINVAL);
+ ret = -1;
+ break;
+ }
+
+ /* Initialise the rest of the mutex: */
+ _thread_queue_init(&mutex->m_queue);
+ mutex->m_flags |= MUTEX_FLAGS_INITED;
+ mutex->m_owner = NULL;
+ mutex->m_type = type;
+
+ /* Unblock signals: */
+ _thread_kern_sig_unblock(status);
+ }
+ /* Return the completion status: */
+ return (ret);
+}
+
+int
+pthread_mutex_destroy(pthread_mutex_t * mutex)
+{
+ int ret = 0;
+ int status;
+
+ /* Block signals: */
+ _thread_kern_sig_block(&status);
+
+ /* Process according to mutex type: */
+ switch (mutex->m_type) {
+ /* Fast mutex: */
+ case MUTEX_TYPE_FAST:
+ /* Nothing to do here. */
+ break;
+
+ /* Counting mutex: */
+ case MUTEX_TYPE_COUNTING_FAST:
+ /* Reset the mutex count: */
+ mutex->m_data.m_count = 0;
+ break;
+
+ /* Trap undefined mutex types: */
+ default:
+ /* Return an invalid argument error: */
+ _thread_seterrno(_thread_run, EINVAL);
+ ret = -1;
+ break;
+ }
+
+ /* Clean up the mutex in case that others want to use it: */
+ _thread_queue_init(&mutex->m_queue);
+ mutex->m_owner = NULL;
+ mutex->m_flags = 0;
+
+ /* Unblock signals: */
+ _thread_kern_sig_unblock(status);
+
+ /* Return the completion status: */
+ return (ret);
+}
+
+int
+pthread_mutex_trylock(pthread_mutex_t * mutex)
+{
+ int ret = 0;
+ int status;
+
+ /* Block signals: */
+ _thread_kern_sig_block(&status);
+
+ /* Process according to mutex type: */
+ switch (mutex->m_type) {
+ /* Fast mutex: */
+ case MUTEX_TYPE_FAST:
+ /* Check if this mutex is not locked: */
+ if (mutex->m_owner == NULL) {
+ /* Lock the mutex for the running thread: */
+ mutex->m_owner = _thread_run;
+ } else {
+ /* Return a busy error: */
+ _thread_seterrno(_thread_run, EBUSY);
+ ret = -1;
+ }
+ break;
+
+ /* Counting mutex: */
+ case MUTEX_TYPE_COUNTING_FAST:
+ /* Check if this mutex is locked: */
+ if (mutex->m_owner != NULL) {
+ /*
+ * Check if the mutex is locked by the running
+ * thread:
+ */
+ if (mutex->m_owner == _thread_run) {
+ /* Increment the lock count: */
+ mutex->m_data.m_count++;
+ } else {
+ /* Return a busy error: */
+ _thread_seterrno(_thread_run, EBUSY);
+ ret = -1;
+ }
+ } else {
+ /* Lock the mutex for the running thread: */
+ mutex->m_owner = _thread_run;
+ }
+ break;
+
+ /* Trap invalid mutex types: */
+ default:
+ /* Return an invalid argument error: */
+ _thread_seterrno(_thread_run, EINVAL);
+ ret = -1;
+ break;
+ }
+
+ /* Unblock signals: */
+ _thread_kern_sig_unblock(status);
+
+ /* Return the completion status: */
+ return (ret);
+}
+
+int
+pthread_mutex_lock(pthread_mutex_t * mutex)
+{
+ int ret = 0;
+ int status;
+
+ /* Block signals: */
+ _thread_kern_sig_block(&status);
+
+ /* Process according to mutex type: */
+ switch (mutex->m_type) {
+ /* Fast mutexes do not check for any error conditions: */
+ case MUTEX_TYPE_FAST:
+ /*
+ * Enter a loop to wait for the mutex to be locked by the
+ * current thread:
+ */
+ while (mutex->m_owner != _thread_run) {
+ /* Check if the mutex is not locked: */
+ if (mutex->m_owner == NULL) {
+ /* Lock the mutex for this thread: */
+ mutex->m_owner = _thread_run;
+ } else {
+ /*
+ * Join the queue of threads waiting to lock
+ * the mutex:
+ */
+ _thread_queue_enq(&mutex->m_queue, _thread_run);
+
+ /* Block signals: */
+ _thread_kern_sched_state(PS_MUTEX_WAIT, __FILE__, __LINE__);
+
+ /* Block signals: */
+ _thread_kern_sig_block(NULL);
+ }
+ }
+ break;
+
+ /* Counting mutex: */
+ case MUTEX_TYPE_COUNTING_FAST:
+ /*
+ * Enter a loop to wait for the mutex to be locked by the
+ * current thread:
+ */
+ while (mutex->m_owner != _thread_run) {
+ /* Check if the mutex is not locked: */
+ if (mutex->m_owner == NULL) {
+ /* Lock the mutex for this thread: */
+ mutex->m_owner = _thread_run;
+
+ /* Reset the lock count for this mutex: */
+ mutex->m_data.m_count = 0;
+ } else {
+ /*
+ * Join the queue of threads waiting to lock
+ * the mutex:
+ */
+ _thread_queue_enq(&mutex->m_queue, _thread_run);
+
+ /* Block signals: */
+ _thread_kern_sched_state(PS_MUTEX_WAIT, __FILE__, __LINE__);
+
+ /* Block signals: */
+ _thread_kern_sig_block(NULL);
+ }
+ }
+
+ /* Increment the lock count for this mutex: */
+ mutex->m_data.m_count++;
+ break;
+
+ /* Trap invalid mutex types: */
+ default:
+ /* Return an invalid argument error: */
+ _thread_seterrno(_thread_run, EINVAL);
+ ret = -1;
+ break;
+ }
+
+ /* Unblock signals: */
+ _thread_kern_sig_unblock(status);
+
+ /* Return the completion status: */
+ return (ret);
+}
+
+int
+pthread_mutex_unlock(pthread_mutex_t * mutex)
+{
+ int ret = 0;
+ int status;
+
+ /* Block signals: */
+ _thread_kern_sig_block(&status);
+
+ /* Process according to mutex type: */
+ switch (mutex->m_type) {
+ /* Fast mutexes do not check for any error conditions: */
+ case MUTEX_TYPE_FAST:
+ /* Check if the running thread is not the owner of the mutex: */
+ if (mutex->m_owner != _thread_run) {
+ /* Return an invalid argument error: */
+ _thread_seterrno(_thread_run, EINVAL);
+ ret = -1;
+ }
+ /*
+ * Get the next thread from the queue of threads waiting on
+ * the mutex:
+ */
+ else if ((mutex->m_owner = _thread_queue_deq(&mutex->m_queue)) != NULL) {
+ /* Allow the new owner of the mutex to run: */
+ mutex->m_owner->state = PS_RUNNING;
+ }
+ break;
+
+ /* Counting mutex: */
+ case MUTEX_TYPE_COUNTING_FAST:
+ /* Check if the running thread is not the owner of the mutex: */
+ if (mutex->m_owner != _thread_run) {
+ /* Return an invalid argument error: */
+ _thread_seterrno(_thread_run, EINVAL);
+ ret = -1;
+ }
+ /* Check if there are still counts: */
+ else if (mutex->m_data.m_count) {
+ /* Decrement the count: */
+ mutex->m_data.m_count--;
+ }
+ /*
+ * Get the next thread from the queue of threads waiting on
+ * the mutex:
+ */
+ else if ((mutex->m_owner = _thread_queue_deq(&mutex->m_queue)) != NULL) {
+ /* Allow the new owner of the mutex to run: */
+ mutex->m_owner->state = PS_RUNNING;
+ }
+ break;
+
+ /* Trap invalid mutex types: */
+ default:
+ /* Return an invalid argument error: */
+ _thread_seterrno(_thread_run, EINVAL);
+ ret = -1;
+ break;
+ }
+
+ /* Unblock signals: */
+ _thread_kern_sig_unblock(status);
+
+ /* Return the completion status: */
+ return (ret);
+}
+#endif
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