diff options
Diffstat (limited to 'lib/libpthread/pthreads/mutex.c')
| -rw-r--r-- | lib/libpthread/pthreads/mutex.c | 223 |
1 files changed, 223 insertions, 0 deletions
diff --git a/lib/libpthread/pthreads/mutex.c b/lib/libpthread/pthreads/mutex.c new file mode 100644 index 000000000000..0f3e9abfca7a --- /dev/null +++ b/lib/libpthread/pthreads/mutex.c @@ -0,0 +1,223 @@ +/* ==== mutex.c ============================================================ + * Copyright (c) 1993, 1994 by Chris Provenzano, proven@mit.edu + * 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 Chris Provenzano. + * 4. The name of Chris Provenzano may not be used to endorse or promote + * products derived from this software without specific prior written + * permission. + * + * THIS SOFTWARE IS PROVIDED BY CHRIS PROVENZANO ``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 CHRIS PROVENZANO 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. + * + * Description : Mutex functions. + * + * 1.00 93/07/19 proven + * -Started coding this file. + */ + +#include <pthread.h> +#include <errno.h> + +/* + * Basic mutex functionality + + * This is the basic lock order + * queue + * pthread + * global + * + * semaphore functionality is defined in machdep.h + */ + +/* ========================================================================== + * pthread_mutex_init() + * + * In this implementation I don't need to allocate memory. + * ENOMEM, EAGAIN should never be returned. Arch that have + * weird constraints may need special coding. + */ +int pthread_mutex_init(pthread_mutex_t *mutex, pthread_mutexattr_t *mutex_attr) +{ + /* Only check if attr specifies some mutex type other than fast */ + if ((mutex_attr) && (mutex_attr->m_type != MUTEX_TYPE_FAST)) { + if (mutex_attr->m_type >= MUTEX_TYPE_MAX) { + return(EINVAL); + } + if (mutex->m_flags & MUTEX_FLAGS_INITED) { + return(EBUSY); + } + mutex->m_type = mutex_attr->m_type; + } else { + mutex->m_type = MUTEX_TYPE_FAST; + } + /* Set all other paramaters */ + pthread_queue_init(&mutex->m_queue); + mutex->m_flags |= MUTEX_FLAGS_INITED; + mutex->m_lock = SEMAPHORE_CLEAR; + mutex->m_owner = NULL; + return(OK); +} + +/* ========================================================================== + * pthread_mutex_destroy() + */ +int pthread_mutex_destroy(pthread_mutex_t *mutex) +{ + /* Only check if mutex is of type other than fast */ + switch(mutex->m_type) { + case MUTEX_TYPE_FAST: + break; + case MUTEX_TYPE_STATIC_FAST: + default: + return(EINVAL); + break; + } + + /* Cleanup mutex, others might want to use it. */ + pthread_queue_init(&mutex->m_queue); + mutex->m_flags |= MUTEX_FLAGS_INITED; + mutex->m_lock = SEMAPHORE_CLEAR; + mutex->m_owner = NULL; + mutex->m_flags = 0; + return(OK); +} + +/* ========================================================================== + * pthread_mutex_trylock() + */ +int pthread_mutex_trylock(pthread_mutex_t *mutex) +{ + semaphore *lock; + int rval; + + lock = &(mutex->m_lock); + while (SEMAPHORE_TEST_AND_SET(lock)) { + pthread_yield(); + } + + switch (mutex->m_type) { + /* + * Fast mutexes do not check for any error conditions. + */ + case MUTEX_TYPE_FAST: + case MUTEX_TYPE_STATIC_FAST: + if (!mutex->m_owner) { + mutex->m_owner = pthread_run; + rval = OK; + } else { + rval = EBUSY; + } + break; + default: + rval = EINVAL; + break; + } + SEMAPHORE_RESET(lock); + return(rval); +} + +/* ========================================================================== + * pthread_mutex_lock() + */ +int pthread_mutex_lock(pthread_mutex_t *mutex) +{ + semaphore *lock, *plock; + int rval; + + lock = &(mutex->m_lock); + while (SEMAPHORE_TEST_AND_SET(lock)) { + pthread_yield(); + } + + switch (mutex->m_type) { + /* + * Fast mutexes do not check for any error conditions. + */ + case MUTEX_TYPE_FAST: + case MUTEX_TYPE_STATIC_FAST: + if (mutex->m_owner) { + plock = &(pthread_run->lock); + while (SEMAPHORE_TEST_AND_SET(plock)) { + pthread_yield(); + } + pthread_queue_enq(&mutex->m_queue, pthread_run); + SEMAPHORE_RESET(lock); + + /* Reschedule will unlock pthread_run */ + reschedule(PS_MUTEX_WAIT); + return(OK); + } + mutex->m_owner = pthread_run; + rval = OK; + break; + default: + rval = EINVAL; + break; + } + SEMAPHORE_RESET(lock); + return(rval); +} + +/* ========================================================================== + * pthread_mutex_unlock() + */ +int pthread_mutex_unlock(pthread_mutex_t *mutex) +{ + struct pthread *pthread; + semaphore *lock, *plock; + int rval; + + lock = &(mutex->m_lock); + while (SEMAPHORE_TEST_AND_SET(lock)) { + pthread_yield(); + } + + switch (mutex->m_type) { + /* + * Fast mutexes do not check for any error conditions. + */ + case MUTEX_TYPE_FAST: + case MUTEX_TYPE_STATIC_FAST: + if (pthread = pthread_queue_get(&mutex->m_queue)) { + plock = &(pthread->lock); + while (SEMAPHORE_TEST_AND_SET(plock)) { + pthread_yield(); + } + mutex->m_owner = pthread; + + /* Reset pthread state */ + pthread_queue_deq(&mutex->m_queue); + pthread->state = PS_RUNNING; + SEMAPHORE_RESET(plock); + } else { + mutex->m_owner = NULL; + } + rval = OK; + break; + default: + rval = EINVAL; + break; + } + SEMAPHORE_RESET(lock); + return(rval); +} |