108 lines
3.4 KiB
C
108 lines
3.4 KiB
C
/****************************************************************************
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* fs/semaphore/sem_close.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 <sched.h>
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#include <assert.h>
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#include <errno.h>
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#include <nuttx/kmalloc.h>
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#include <nuttx/semaphore.h>
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#include <nuttx/fs/fs.h>
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#include "inode/inode.h"
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#include "notify/notify.h"
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#ifdef CONFIG_FS_NAMED_SEMAPHORES
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: nxsem_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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* Input Parameters:
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* sem - semaphore descriptor
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*
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* Returned Value:
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* 0 (OK), or negated errno 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 nxsem_close(FAR sem_t *sem)
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{
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FAR struct nsem_inode_s *nsem;
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struct inode *inode;
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DEBUGASSERT(sem);
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/* Upcast to get back to out internal representation */
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nsem = (FAR struct nsem_inode_s *)sem;
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DEBUGASSERT(nsem->ns_inode);
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inode = nsem->ns_inode;
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/* If the semaphore was previously unlinked and the reference count has
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* decremented to zero, then release the semaphore and delete the inode
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* now.
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*/
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if (atomic_fetch_sub(&inode->i_crefs, 1) <= 1)
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{
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nxsem_destroy(&nsem->ns_sem);
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group_free(NULL, nsem);
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/* Release and free the inode container. If it has been properly
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* unlinked, then the peer pointer should be NULL.
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*/
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#ifdef CONFIG_FS_NOTIFY
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notify_close2(inode);
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#endif
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DEBUGASSERT(inode->i_peer == NULL);
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inode_free(inode);
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}
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return OK;
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}
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#endif /* CONFIG_FS_NAMED_SEMAPHORES */
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