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https://github.com/apache/nuttx.git
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Add logic to automatically wrap a block device as a BCH device with no visible character device
This commit is contained in:
Gregory Nutt
@@ -1,7 +1,7 @@
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/****************************************************************************
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* drivers/bch/bchdev_driver.c
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*
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* Copyright (C) 2008-2009, 2014 Gregory Nutt. All rights reserved.
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* Copyright (C) 2008-2009, 2014-2015 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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+4
-1
@@ -41,10 +41,13 @@ CSRCS += fs_registerdriver.c fs_unregisterdriver.c
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# Don't build-in block driver support if there are no mountpoints
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ifneq ($(CONFIG_DISABLE_MOUNTPOINT),y)
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CSRCS += fs_registerblockdriver.c fs_unregisterblockdriver.c
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CSRCS += fs_findblockdriver.c fs_openblockdriver.c fs_closeblockdriver.c
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ifneq ($(CONFIG_DISABLE_PSEUDOFS_OPERATIONS),y)
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CSRCS += fs_blockproxy.c
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endif
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endif
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# System logging to a character device (or file)
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@@ -0,0 +1,246 @@
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/****************************************************************************
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* fs/driver/fs_blockproxy.c
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*
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* Copyright (C) 2015 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 <sys/types.h>
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#include <sys/stat.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <fcntl.h>
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#include <semaphore.h>
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#include <string.h>
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#include <errno.h>
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#include <assert.h>
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#include <debug.h>
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#include <nuttx/kmalloc.h>
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#include <nuttx/fs/fs.h>
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#if !defined(CONFIG_DISABLE_PSEUDOFS_OPERATIONS) && \
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!defined(CONFIG_DISABLE_MOUNTPOINT)
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/****************************************************************************
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* Pre-processor oDefinitions
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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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* Public Data
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****************************************************************************/
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static uint32_t g_devno;
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static sem_t g_devno_sem = SEM_INITIALIZER(1);
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: unique_chardev
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*
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* Description:
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* Create a unique temporary device name in the /dev/ directory of the
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* psuedo-file system. We cannot use mktemp for this because it will
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* attempt to open() the file.
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*
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* Input parameters:
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* None
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*
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* Returned Value:
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* The allocated path to the device. This must be released by the caller
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* to prevent memory links. NULL will be returned only the case where
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* we fail to allocate memory.
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*
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****************************************************************************/
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static FAR char *unique_chardev(void)
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{
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struct stat statbuf;
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char devbuf[16];
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uint32_t devno;
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int ret;
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/* Loop until we get a unique device name */
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for (; ; )
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{
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/* Get the semaphore protecting the path number */
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while (sem_wait(&g_devno_sem) < 0)
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{
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DEBUGASSERT(errno == EINTR);
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}
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/* Get the next device number and release the semaphore */
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devno = ++g_devno;
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sem_post(&g_devno_sem);
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/* Construct the full device number */
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devno &= 0xffffff;
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snprintf(devbuf, 16, "/dev/tmp%06lx", (unsigned long)devno);
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/* Make sure that file name is not in use */
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ret = stat(devbuf, &statbuf);
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if (ret < 0)
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{
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DEBUGASSERT(errno == ENOENT);
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return strdup(devbuf);
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}
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/* It is in use, try again */
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}
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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: block_proxy
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*
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* Description:
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* Create a temporary char driver using drivers/bch that mediate character
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* oriented accessed to the block driver.
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*
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* Input parameters:
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* blkdev - The path to the block driver
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* mode - Character driver access priviledges
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*
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* Returned Value:
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* If positive, non-zero file descriptor is returned on success. This
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* is the file descriptor of the nameless character driver that mediates
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* accesses to the block driver.
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*
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* Errors that may be returned:
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*
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* ENOMEM - Failed to create a temporay path name.
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*
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* Plus:
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*
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* - Errors reported from bchdev_register()
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* - Errors reported from open() or unlink()
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*
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****************************************************************************/
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int block_proxy(FAR const char *blkdev, mode_t mode)
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{
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FAR char *chardev;
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bool readonly;
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int ret;
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int fd;
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DEBUGASSERT(blkdev);
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DEBUGASSERT((mode & (O_CREAT | O_EXCL | O_APPEND | O_TRUNC)) == 0);
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/* Create a unique temporary file name for the character device */
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chardev = unique_chardev();
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if (chardev == NULL)
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{
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fdbg("ERROR: Failed to create temporary device name\n");
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return -ENOMEM;
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}
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/* Should this character driver be read-only? */
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readonly = ((mode & O_WROK) == 0);
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/* Wrap the block driver with an instance of the BCH driver */
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ret = bchdev_register(blkdev, chardev, readonly);
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if (ret < 0)
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{
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fdbg("ERROR: bchdev_register(%s, %s) failed: %d\n",
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blkdev, chardev, ret);
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goto errout_with_chardev;
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}
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/* Open the newly created character driver */
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mode &= ~(O_CREAT | O_EXCL | O_APPEND | O_TRUNC);
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fd = open(chardev, mode);
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if (fd < 0)
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{
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ret = -errno;
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fdbg("ERROR: Failed to open %s: %d\n", chardev, ret);
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goto errout_with_bchdev;
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}
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/* Unlink the character device name. The driver instance will persist,
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* provided that CONFIG_DISABLE_PSEUDOFS_OPERATIONS=y (otherwise, we have
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* a problem here!)
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*/
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ret = unlink(chardev);
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if (ret < 0)
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{
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ret = -errno;
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fdbg("ERROR: Failed to unlink %s: %d\n", chardev, ret);
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}
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/* Free the allocate character driver name and return the open file
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* descriptor.
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*/
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kmm_free(chardev);
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return fd;
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errout_with_bchdev:
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(void)unlink(chardev);
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errout_with_chardev:
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kmm_free(chardev);
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return ret;
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}
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#endif /* !CONFIG_DISABLE_PSEUDOFS_OPERATIONS && !CONFIG_DISABLE_MOUNTPOINT */
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