freebsd-dev/lib/libc_r/uthread/uthread_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