6a3c2aded6
* Simplify EINTR/ECANCEL error handling 1. Add semaphore uninterruptible wait function 2 .Replace semaphore wait loop with a single uninterruptible wait 3. Replace all sem_xxx to nxsem_xxx * Unify the void cast usage 1. Remove void cast for function because many place ignore the returned value witout cast 2. Replace void cast for variable with UNUSED macro
159 lines
4.3 KiB
C
159 lines
4.3 KiB
C
/****************************************************************************
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* libs/libc/pthread/pthread_rwlock_rdlock.c
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*
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* Copyright (C) 2017 Mark Schulte. All rights reserved.
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* Author: Mark Schulte <mark@mjs.pw>
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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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*
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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
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* 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 THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdint.h>
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#include <pthread.h>
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#include <errno.h>
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#include <debug.h>
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#include <nuttx/semaphore.h>
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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#ifdef CONFIG_PTHREAD_CLEANUP
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static void rdlock_cleanup(FAR void *arg)
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{
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FAR pthread_rwlock_t *rw_lock = (FAR pthread_rwlock_t *)arg;
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pthread_mutex_unlock(&rw_lock->lock);
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}
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#endif
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static int tryrdlock(FAR pthread_rwlock_t *rw_lock)
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{
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int err;
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if (rw_lock->num_writers > 0 || rw_lock->write_in_progress)
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{
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err = EBUSY;
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}
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else if (rw_lock->num_readers == UINT_MAX)
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{
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err = EAGAIN;
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}
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else
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{
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rw_lock->num_readers++;
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err = OK;
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}
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return err;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: pthread_rwlock_rdlock
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*
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* Description:
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* Locks a read/write lock for reading
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*
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* Input Parameters:
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* None
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*
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* Returned Value:
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* None
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*
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* Assumptions:
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*
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****************************************************************************/
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int pthread_rwlock_tryrdlock(FAR pthread_rwlock_t *rw_lock)
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{
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int err = pthread_mutex_trylock(&rw_lock->lock);
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if (err != 0)
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{
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return err;
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}
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err = tryrdlock(rw_lock);
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pthread_mutex_unlock(&rw_lock->lock);
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return err;
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}
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int pthread_rwlock_timedrdlock(FAR pthread_rwlock_t *rw_lock,
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FAR const struct timespec *ts)
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{
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int err = pthread_mutex_lock(&rw_lock->lock);
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if (err != 0)
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{
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return err;
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}
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#ifdef CONFIG_PTHREAD_CLEANUP
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pthread_cleanup_push(&rdlock_cleanup, rw_lock);
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#endif
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while ((err = tryrdlock(rw_lock)) == EBUSY)
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{
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if (ts != NULL)
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{
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err = pthread_cond_timedwait(&rw_lock->cv, &rw_lock->lock, ts);
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}
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else
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{
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err = pthread_cond_wait(&rw_lock->cv, &rw_lock->lock);
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}
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if (err != 0)
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{
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break;
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}
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}
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#ifdef CONFIG_PTHREAD_CLEANUP
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pthread_cleanup_pop(0);
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#endif
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pthread_mutex_unlock(&rw_lock->lock);
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return err;
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}
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int pthread_rwlock_rdlock(FAR pthread_rwlock_t * rw_lock)
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{
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return pthread_rwlock_timedrdlock(rw_lock, NULL);
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}
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