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- /****************************************************************************
- * fs/semaphore/sem_close.c
- *
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership. The
- * ASF licenses this file to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance with the
- * License. You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
- * License for the specific language governing permissions and limitations
- * under the License.
- *
- ****************************************************************************/
- /****************************************************************************
- * Included Files
- ****************************************************************************/
- #include <nuttx/config.h>
- #include <sched.h>
- #include <errno.h>
- #include <nuttx/kmalloc.h>
- #include <nuttx/semaphore.h>
- #include <nuttx/fs/fs.h>
- #include "inode/inode.h"
- #ifdef CONFIG_FS_NAMED_SEMAPHORES
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: sem_close
- *
- * Description:
- * This function is called to indicate that the calling task is finished
- * with the specified named semaphore, 'sem'. The sem_close() deallocates
- * any system resources allocated by the system for this named semaphore.
- *
- * If the semaphore has not been removed with a call to sem_unlink(), then
- * sem_close() has no effect on the named semaphore. However, when the
- * named semaphore has been fully unlinked, the semaphore will vanish when
- * the last task closes it.
- *
- * Input Parameters:
- * sem - semaphore descriptor
- *
- * Returned Value:
- * 0 (OK), or -1 (ERROR) if unsuccessful.
- *
- * Assumptions:
- * - Care must be taken to avoid risking the deletion of a semaphore that
- * another calling task has already locked.
- * - sem_close must not be called for an un-named semaphore
- *
- ****************************************************************************/
- int sem_close(FAR sem_t *sem)
- {
- FAR struct nsem_inode_s *nsem;
- struct inode *inode;
- int ret;
- DEBUGASSERT(sem);
- /* Upcast to get back to out internal representation */
- nsem = (FAR struct nsem_inode_s *)sem;
- DEBUGASSERT(nsem->ns_inode);
- inode = nsem->ns_inode;
- /* Decrement the reference count on the inode */
- do
- {
- ret = inode_semtake();
- /* The only error that is expected is due to thread cancellation.
- * At this point, we must continue to free the semaphore anyway.
- */
- DEBUGASSERT(ret == OK || ret == -ECANCELED);
- }
- while (ret < 0);
- if (inode->i_crefs > 0)
- {
- inode->i_crefs--;
- }
- /* If the semaphore was previously unlinked and the reference count has
- * decremented to zero, then release the semaphore and delete the inode
- * now.
- */
- if (inode->i_crefs <= 0 && (inode->i_flags & FSNODEFLAG_DELETED) != 0)
- {
- /* Destroy the semaphore and free the container */
- nxsem_destroy(&nsem->ns_sem);
- group_free(NULL, nsem);
- /* Release and free the inode container. If it has been properly
- * unlinked, then the peer pointer should be NULL.
- */
- inode_semgive();
- DEBUGASSERT(inode->i_peer == NULL);
- inode_free(inode);
- return OK;
- }
- inode_semgive();
- return OK;
- }
- #endif /* CONFIG_FS_NAMED_SEMAPHORES */
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