91 lines
3.9 KiB
C
91 lines
3.9 KiB
C
/****************************************************************************
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* libs/libc/pthread/pthread_mutex_lock.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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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 <pthread.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: pthread_mutex_lock
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*
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* Description:
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* The mutex object referenced by mutex is locked by calling
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* pthread_mutex_lock(). If the mutex is already locked, the calling thread
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* blocks until the mutex becomes available. This operation returns with
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* the mutex object referenced by mutex in the locked state with the
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* calling thread as its owner.
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*
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* If the mutex type is PTHREAD_MUTEX_NORMAL, deadlock detection is not
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* provided. Attempting to relock the mutex causes deadlock. If a thread
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* attempts to unlock a mutex that it has not locked or a mutex which is
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* unlocked, undefined behavior results.
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*
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* If the mutex type is PTHREAD_MUTEX_ERRORCHECK, then error checking is
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* provided. If a thread attempts to relock a mutex that it has already
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* locked, an error will be returned. If a thread attempts to unlock a
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* mutex that it has not locked or a mutex which is unlocked, an error will
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* be returned.
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*
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* If the mutex type is PTHREAD_MUTEX_RECURSIVE, then the mutex maintains
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* the concept of a lock count. When a thread successfully acquires a mutex
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* for the first time, the lock count is set to one. Every time a thread
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* relocks this mutex, the lock count is incremented by one. Each time the
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* thread unlocks the mutex, the lock count is decremented by one. When the
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* lock count reaches zero, the mutex becomes available for other threads
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* to acquire. If a thread attempts to unlock a mutex that it has not
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* locked or a mutex which is unlocked, an error will be returned.
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*
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* If a signal is delivered to a thread waiting for a mutex, upon return
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* from the signal handler the thread resumes waiting for the mutex as if
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* it was not interrupted.
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*
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* Input Parameters:
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* mutex - A reference to the mutex to be locked.
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*
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* Returned Value:
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* 0 on success or an errno value on failure. Note that the errno EINTR
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* is never returned by pthread_mutex_lock().
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*
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* Assumptions:
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*
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* POSIX Compatibility:
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* - This implementation does not return EAGAIN when the mutex could not be
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* acquired because the maximum number of recursive locks for mutex has
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* been exceeded.
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*
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****************************************************************************/
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int pthread_mutex_lock(FAR pthread_mutex_t *mutex)
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{
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/* pthread_mutex_lock() is equivalent to pthread_mutex_timedlock() when
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* the absolute time delay is a NULL value.
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*/
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return pthread_mutex_timedlock(mutex, NULL);
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}
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