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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/sem_destroy.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/sem_destroy.c')
-rw-r--r-- | nuttx/sched/sem_destroy.c | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/nuttx/sched/sem_destroy.c b/nuttx/sched/sem_destroy.c new file mode 100644 index 000000000..90a2b95ef --- /dev/null +++ b/nuttx/sched/sem_destroy.c @@ -0,0 +1,126 @@ +/**************************************************************************** + * lib/semaphore/sem_destroy.c + * + * Copyright (C) 2007-2009, 2011 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 <semaphore.h> +#include <errno.h> + +#include "sem_internal.h" + +/**************************************************************************** + * Definitions + ****************************************************************************/ + +/**************************************************************************** + * Private Type Declarations + ****************************************************************************/ + +/**************************************************************************** + * Global Variables + ****************************************************************************/ + +/**************************************************************************** + * Private Variables + ****************************************************************************/ + +/**************************************************************************** + * Private Functions + ****************************************************************************/ + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: sem_destroy + * + * Description: + * This function is used to destroy the un-named semaphore indicated by + * 'sem'. Only a semaphore that was created using sem_init() may be + * destroyed using sem_destroy(); the effect of calling sem_destroy() with + * a named semaphore is undefined. The effect of subsequent use of the + * semaphore sem is undefined until sem is re-initialized by another call + * to sem_init(). + * + * The effect of destroying a semaphore upon which other processes are + * currently blocked is undefined. + * + * Parameters: + * sem - Semaphore to be destroyed. + * + * Return Value: + * 0 (OK), or -1 (ERROR) if unsuccessful. + * + * Assumptions: + * + ****************************************************************************/ + +int sem_destroy (FAR sem_t *sem) +{ + /* Assure a valid semaphore is specified */ + + if (sem) + { + /* There is really no particular action that we need + * take to destroy a semaphore. We will just reset + * the count to some reasonable value (1) and release + * ownership. + * + * Check if other threads are waiting on the semaphore. + * In this case, the behavior is undefined. We will: + * leave the count unchanged but still return OK. + */ + + if (sem->semcount >= 0) + { + sem->semcount = 1; + } + + /* Release holders of the semaphore */ + + sem_destroyholder(sem); + return OK; + } + else + { + errno = -EINVAL; + return ERROR; + } +} |