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140 lines
5.0 KiB
140 lines
5.0 KiB
/**************************************************************************** |
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* sched/sem_close.c |
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* |
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* Copyright (C) 2007-2009 Gregory Nutt. All rights reserved. |
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* Author: Gregory Nutt <gnutt@nuttx.org> |
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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 <errno.h> |
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#include <semaphore.h> |
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#include <sched.h> |
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#include "os_internal.h" |
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#include "sem_internal.h" |
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/**************************************************************************** |
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* Definitions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Type Declarations |
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****************************************************************************/ |
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/**************************************************************************** |
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* Global Variables |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Variables |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Functions |
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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: sem_close |
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* |
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* Description: |
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* This function is called to indicate that the calling task is finished |
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* with the specified named semaphore, 'sem'. The sem_close() deallocates |
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* any system resources allocated by the system for this named semaphore. |
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* |
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* If the semaphore has not been removed with a call to sem_unlink(), then |
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* sem_close() has no effect on the named semaphore. However, when the |
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* named semaphore has been fully unlinked, the semaphore will vanish when |
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* the last task closes it. |
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* |
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* Parameters: |
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* sem - semaphore descriptor |
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* |
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* Return Value: |
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* 0 (OK), or -1 (ERROR) if unsuccessful. |
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* |
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* Assumptions: |
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* - Care must be taken to avoid risking the deletion of a semaphore that |
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* another calling task has already locked. |
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* - sem_close must not be called for an un-named semaphore |
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* |
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****************************************************************************/ |
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int sem_close(FAR sem_t *sem) |
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{ |
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FAR nsem_t *psem; |
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int ret = ERROR; |
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/* Verify the inputs */ |
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if (sem) |
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{ |
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sched_lock(); |
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/* Search the list of named semaphores */ |
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for (psem = (FAR nsem_t*)g_nsems.head; |
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((psem) && (sem != &psem->sem)); |
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psem = psem->flink); |
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/* Check if we found it */ |
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if (psem) |
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{ |
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/* Decrement the count of sem_open connections to this semaphore */ |
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if (psem->nconnect) psem->nconnect--; |
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/* If the semaphore is no long connected to any processes AND the |
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* semaphore was previously unlinked, then deallocate it. |
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*/ |
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if (!psem->nconnect && psem->unlinked) |
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{ |
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dq_rem((FAR dq_entry_t*)psem, &g_nsems); |
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sched_free(psem); |
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} |
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ret = OK; |
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} |
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sched_unlock(); |
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} |
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return ret; |
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}
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