09a9611ae9
Example: When executing "df -h" on Core A to view mount information, this process will traverse inode nodes, thereby holding the inode_lock. Since the inode type of the mount point may be rpmsgfs, it will fetch statfs information from another Core B. Meanwhile, rcS on Core B needs to obtain file information from Core A, which will be achieved by fetching stat information through rpmsgfs. When this message arrives at Core A, a deadlock can occur between Core A's rptun ap and nsh task. However, both of these places involve read operations only, thus a reader-writer lock can be utilized to prevent such a deadlock. Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>
114 lines
3.6 KiB
C
114 lines
3.6 KiB
C
/****************************************************************************
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* fs/inode/fs_inode.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/fs/fs.h>
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#include <nuttx/rwsem.h>
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#include "inode/inode.h"
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/****************************************************************************
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* Private Types
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****************************************************************************/
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static rw_semaphore_t g_inode_lock = RWSEM_INITIALIZER;
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: inode_initialize
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*
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* Description:
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* This is called from the OS initialization logic to configure the file
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* system.
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*
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****************************************************************************/
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void inode_initialize(void)
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{
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/* Reserve the root node */
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inode_root_reserve();
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}
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/****************************************************************************
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* Name: inode_lock
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*
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* Description:
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* Get writeable exclusive access to the in-memory inode tree.
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*
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****************************************************************************/
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void inode_lock(void)
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{
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down_write(&g_inode_lock);
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}
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/****************************************************************************
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* Name: inode_rlock
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*
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* Description:
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* Get readable exclusive access to the in-memory inode tree.
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*
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****************************************************************************/
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void inode_rlock(void)
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{
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down_read(&g_inode_lock);
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}
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/****************************************************************************
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* Name: inode_unlock
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*
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* Description:
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* Relinquish writeable exclusive access to the in-memory inode tree.
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*
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****************************************************************************/
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void inode_unlock(void)
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{
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up_write(&g_inode_lock);
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}
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/****************************************************************************
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* Name: inode_runlock
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*
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* Description:
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* Relinquish read exclusive access to the in-memory inode tree.
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*
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****************************************************************************/
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void inode_runlock(void)
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{
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up_read(&g_inode_lock);
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}
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