drivers/bch/bchdev_unregister.c

/****************************************************************************
 * drivers/bch/bchdev_unregister.c
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * 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 <sys/stat.h>
#include <sys/ioctl.h>

#include <unistd.h>
#include <fcntl.h>
#include <sched.h>
#include <errno.h>
#include <assert.h>
#include <nuttx/debug.h>

#include <nuttx/fs/fs.h>
#include <nuttx/fs/ioctl.h>
#include <nuttx/drivers/drivers.h>

#include "bch.h"

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: bchdev_unregister
 *
 * Description:
 *   Unregister character driver access to a block device that was created
 *   by a previous call to bchdev_register().
 *
 ****************************************************************************/

int bchdev_unregister(FAR const char *chardev)
{
  FAR struct bchlib_s *bch;
  struct file filestruct;
  int ret;

  /* Sanity check */

#ifdef CONFIG_DEBUG_FEATURES
  if (!chardev)
    {
      return -EINVAL;
    }
#endif

  /* Open the character driver associated with chardev */

  ret = file_open(&filestruct, chardev, O_RDONLY | O_CLOEXEC);
  if (ret < 0)
    {
      _err("ERROR: Failed to open %s: %d\n", chardev, ret);
      return ret;
    }

  /* Get a reference to the internal data structure.  On success, we
   * will hold a reference count on the state structure.
   */

  ret = file_ioctl(&filestruct, DIOC_GETPRIV,
                   (unsigned long)((uintptr_t)&bch));
  file_close(&filestruct);

  if (ret < 0)
    {
      _err("ERROR: ioctl failed: %d\n", ret);
      return ret;
    }

  /* Check if the internal structure is non-busy (we hold one reference). */

  if (bch->refs > 1)
    {
      ret = -EBUSY;
      goto errout_with_lock;
    }

  /* Unregister the driver (this cannot suspend or we lose our non-preemptive
   * state!).  Once the driver is successfully unregistered, we can assume
   * we have exclusive access to the state instance.
   */

  ret = unregister_driver(chardev);
  if (ret < 0)
    {
      goto errout_with_lock;
    }

  /* Release the internal structure */

  bch->refs = 0;
  return bchlib_teardown(bch);

errout_with_lock:
  bch->refs--;
  return ret;
}