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Diffstat (limited to 'nuttx/sched/pthread_mutexunlock.c')
| -rw-r--r-- | nuttx/sched/pthread_mutexunlock.c | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/nuttx/sched/pthread_mutexunlock.c b/nuttx/sched/pthread_mutexunlock.c new file mode 100644 index 000000000..34846f952 --- /dev/null +++ b/nuttx/sched/pthread_mutexunlock.c @@ -0,0 +1,164 @@ +/**************************************************************************** + * sched/pthread_mutexunlock.c + * + * Copyright (C) 2007-2009 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <gnutt@nuttx.org> + * + * 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. Neither the name NuttX nor the names of its contributors may be + * used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 + * COPYRIGHT OWNER 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. + * + ****************************************************************************/ + +/**************************************************************************** + * Included Files + ****************************************************************************/ + +#include <nuttx/config.h> + +#include <unistd.h> +#include <pthread.h> +#include <sched.h> +#include <errno.h> +#include <debug.h> + +#include "pthread_internal.h" + +/**************************************************************************** + * Definitions + ****************************************************************************/ + +/**************************************************************************** + * Private Type Declarations + ****************************************************************************/ + +/**************************************************************************** + * Global Variables + ****************************************************************************/ + +/**************************************************************************** + * Private Variables + ****************************************************************************/ + +/**************************************************************************** + * Private Functions + ****************************************************************************/ + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: pthread_mutex_unlock + * + * Description: + * The pthread_mutex_unlock() function releases the mutex object referenced + * by mutex. The manner in which a mutex is released is dependent upon the + * mutex's type attribute. If there are threads blocked on the mutex object + * referenced by mutex when pthread_mutex_unlock() is called, resulting in + * the mutex becoming available, the scheduling policy is used to determine + * which thread shall acquire the mutex. (In the case of PTHREAD_MUTEX_RECURSIVE + * mutexes, the mutex becomes available when the count reaches zero and the + * calling thread no longer has any locks on this mutex). + * + * If a signal is delivered to a thread waiting for a mutex, upon return from + * the signal handler the thread resumes waiting for the mutex as if it was + * not interrupted. + * + * Parameters: + * None + * + * Return Value: + * None + * + * Assumptions: + * + ****************************************************************************/ + +int pthread_mutex_unlock(FAR pthread_mutex_t *mutex) +{ + int ret = OK; + + sdbg("mutex=0x%p\n", mutex); + + if (!mutex) + { + ret = EINVAL; + } + else + { + /* Make sure the semaphore is stable while we make the following + * checks. This all needs to be one atomic action. + */ + + sched_lock(); + + /* Does the calling thread own the semaphore? */ + + if (mutex->pid != (int)getpid()) + { + /* No... return an error (default behavior is like PTHREAD_MUTEX_ERRORCHECK) */ + + sdbg("Holder=%d returning EPERM\n", mutex->pid); + ret = EPERM; + } + + + /* Yes, the caller owns the semaphore.. Is this a recursive mutex? */ + +#ifdef CONFIG_MUTEX_TYPES + else if (mutex->type == PTHREAD_MUTEX_RECURSIVE && mutex->nlocks > 1) + { + /* This is a recursive mutex and we there are multiple locks held. Retain + * the mutex lock, just decrement the count of locks held, and return + * success. + */ + mutex->nlocks--; + } +#endif + + /* This is either a non-recursive mutex or is the outermost unlock of + * a recursive mutex. + */ + + else + { + /* Nullify the pid and lock count then post the semaphore */ + + mutex->pid = 0; +#ifdef CONFIG_MUTEX_TYPES + mutex->nlocks = 0; +#endif + ret = pthread_givesemaphore((sem_t*)&mutex->sem); + } + sched_unlock(); + } + + sdbg("Returning %d\n", ret); + return ret; +} + + |