text: /****************************************************************************
   *
   * Copyright 2016 Samsung Electronics All Rights Reserved.
   *
   * Licensed 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.
   *
   ****************************************************************************/
  /****************************************************************************
   * libc/wqueue/work_cancel.c
   *
   *   Copyright (C) 2009-2010, 2012-2014 Gregory Nutt. All rights reserved.
   *   Author: Gregory Nutt <gnutt@nuttx.org>
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   * 3. Neither the name NuttX nor the names of its contributors may be
   *    used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
   * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
   * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   *
   ****************************************************************************/
  
  /****************************************************************************
   * Included Files
   ****************************************************************************/
  
  #include <tinyara/config.h>
  
  #include <queue.h>
  #include <assert.h>
  #include <errno.h>
  
  #include <tinyara/arch.h>
  #include <tinyara/wqueue.h>
  
  #include "wqueue/wqueue.h"
  
  #if defined(CONFIG_LIB_USRWORK) && !defined(__KERNEL__)
  
  /****************************************************************************
   * Pre-processor Definitions
   ****************************************************************************/
  
  /****************************************************************************
   * Private Type Declarations
   ****************************************************************************/
  
  /****************************************************************************
   * Public Variables
   ****************************************************************************/
  
  /****************************************************************************
   * Private Variables
   ****************************************************************************/
  
  /****************************************************************************
   * Private Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: work_qcancel
   *
   * Description:
   *   Cancel previously queued work.  This removes work from the work queue.
   *   After work has been cancelled, it may be re-queue by calling work_queue()
   *   again.
   *
   * Input parameters:
   *   qid    - The work queue ID
   *   work   - The previously queue work structure to cancel
   *
   * Returned Value:
   *   Zero (OK) on success, a negated errno on failure.  This error may be
   *   reported:
   *
   *   -ENOENT - There is no such work queued.
   *   -EINVAL - An invalid work queue was specified
   *
   ****************************************************************************/
  
  static int work_qcancel(FAR struct usr_wqueue_s *wqueue, FAR struct work_s *work)
  {
  	int ret = -ENOENT;
  
  	DEBUGASSERT(work != NULL);
  
  	/* Get exclusive access to the work queue */
  
  	while (work_lock() < 0);
  
  	/* Cancelling the work is simply a matter of removing the work structure
  	 * from the work queue.  This must be done with interrupts disabled because
  	 * new work is typically added to the work queue from interrupt handlers.
  	 */
  
  	if (work->worker != NULL) {
  		/* A little test of the integrity of the work queue */
  
  		DEBUGASSERT(work->dq.flink || (FAR dq_entry_t *)work == wqueue->q.tail);
  		DEBUGASSERT(work->dq.blink || (FAR dq_entry_t *)work == wqueue->q.head);
  
  		/* Remove the entry from the work queue and make sure that it is
  		 * mark as available (i.e., the worker field is nullified).
  		 */
  
  		dq_rem((FAR dq_entry_t *)work, &wqueue->q);
  		work->worker = NULL;
  		ret = OK;
  	}
  
  	work_unlock();
  	return ret;
  }
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: work_cancel
   *
   * Description:
   *   Cancel previously queued user-mode work.  This removes work from the
   *   user mode work queue.  After work has been cancelled, it may be re-queue
   *   by calling work_queue() again.
   *
   * Input parameters:
   *   qid    - The work queue ID (must be USRWORK)
   *   work   - The previously queue work structure to cancel
   *
   * Returned Value:
   *   Zero (OK) on success, a negated errno on failure.  This error may be
   *   reported:
   *
   *   -ENOENT - There is no such work queued.
   *
   ****************************************************************************/
  
  int work_cancel(int qid, FAR struct work_s *work)
  {
  	if (qid == USRWORK) {
  		return work_qcancel(&g_usrwork, work);
  	} else {
  		return -EINVAL;
  	}
  }
  
  #endif							/* CONFIG_LIB_USRWORK && !__KERNEL__ */
  