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author | px4dev <px4@purgatory.org> | 2012-08-04 15:12:36 -0700 |
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committer | px4dev <px4@purgatory.org> | 2012-08-04 15:12:36 -0700 |
commit | 8a365179eafdf3aea98e60ab9f5882b200d4c759 (patch) | |
tree | 4f38d6d4cd80bd0b6e22e2bb534c3f117ce44e56 /nuttx/sched/pthread_mutextrylock.c | |
download | px4-firmware-8a365179eafdf3aea98e60ab9f5882b200d4c759.tar.gz px4-firmware-8a365179eafdf3aea98e60ab9f5882b200d4c759.tar.bz2 px4-firmware-8a365179eafdf3aea98e60ab9f5882b200d4c759.zip |
Fresh import of the PX4 firmware sources.
Diffstat (limited to 'nuttx/sched/pthread_mutextrylock.c')
-rw-r--r-- | nuttx/sched/pthread_mutextrylock.c | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/nuttx/sched/pthread_mutextrylock.c b/nuttx/sched/pthread_mutextrylock.c new file mode 100644 index 000000000..d88012b51 --- /dev/null +++ b/nuttx/sched/pthread_mutextrylock.c @@ -0,0 +1,147 @@ +/**************************************************************************** + * sched/pthread_mutextrylock.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 <semaphore.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_trylock + * + * Description: + * The function pthread_mutex_trylock() is identical to pthread_mutex_lock() + * except that if the mutex object referenced by mutex is currently locked + * (by any thread, including the current thread), the call returns immediately + * with the errno EBUSY. + * + * 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: + * mutex - A reference to the mutex to be locked. + * + * Return Value: + * 0 on success or an errno value on failure. Note that the errno EINTR + * is never returned by pthread_mutex_lock(). + * + * Assumptions: + * + ****************************************************************************/ + +int pthread_mutex_trylock(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(); + + /* Try to get the semaphore. */ + + if (sem_trywait((sem_t*)&mutex->sem) == OK) + { + /* If we succussfully obtained the semaphore, then indicate + * that we own it. + */ + + mutex->pid = (int)getpid(); + } + + /* Was it not available? */ + + else if (get_errno() == EAGAIN) + { + ret = EBUSY; + } + else + { + ret = EINVAL; + } + + sched_unlock(); + } + + sdbg("Returning %d\n", ret); + return ret; +} + + + |