nuttx/sched/wdog/wd_cancel.c

/****************************************************************************
 * sched/wdog/wd_cancel.c
 *
 *   Copyright (C) 2007-2009, 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,
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 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <stdbool.h>
#include <assert.h>
#include <wdog.h>
#include <nuttx/arch.h>

#include "sched/sched.h"
#include "wdog/wdog.h"

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/****************************************************************************
 * Private Type Declarations
 ****************************************************************************/

/****************************************************************************
 * Global Variables
 ****************************************************************************/

/****************************************************************************
 * Private Variables
 ****************************************************************************/

/****************************************************************************
 * Private Functions
 ****************************************************************************/

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

/****************************************************************************
 * Name: wd_cancel
 *
 * Description:
 *   This function cancels a currently running watchdog timer. Watchdog
 *   timers may be cancelled from the interrupt level.
 *
 * Parameters:
 *   wdog - ID of the watchdog to cancel.
 *
 * Return Value:
 *   OK or ERROR
 *
 * Assumptions:
 *
 ****************************************************************************/

int wd_cancel(WDOG_ID wdog)
{
  wdog_t    *curr;
  wdog_t    *prev;
  irqstate_t saved_state;
  int        ret = ERROR;

  /* Prohibit timer interactions with the timer queue until the
   * cancellation is complete
   */

  saved_state = irqsave();

  /* Make sure that the watchdog is initialized (non-NULL) and is still
   * active.
   */

  if (wdog && WDOG_ISACTIVE(wdog))
    {
      /* Search the g_wdactivelist for the target FCB.  We can't use sq_rem
       * to do this because there are additional operations that need to be
       * done.
       */

      prev = NULL;
      curr = (wdog_t*)g_wdactivelist.head;

      while ((curr) && (curr != wdog))
        {
          prev = curr;
          curr = curr->next;
        }

      /* Check if the watchdog was found in the list.  If not, then an OS
       * error has occurred because the watchdog is marked active!
       */

      ASSERT(curr);

      /* If there is a watchdog in the timer queue after the one that
       * is being cancelled, then it inherits the remaining ticks.
       */

      if (curr->next)
        {
          curr->next->lag += curr->lag;
        }

      /* Now, remove the watchdog from the timer queue */

      if (prev)
        {
          /* Remove the watchdog from mid- or end-of-queue */

          (void)sq_remafter((FAR sq_entry_t*)prev, &g_wdactivelist);
        }
      else
        {
          /* Remove the watchdog at the head of the queue */

          (void)sq_remfirst(&g_wdactivelist);

          /* Reassess the interval timer that will generate the next
           * interval event.
           */

          sched_timer_reassess();
        }

      /* Mark the watchdog inactive */

      wdog->next = NULL;
      WDOG_CLRACTIVE(wdog);

      /* Return success */

      ret = OK;
    }

  irqrestore(saved_state);
  return ret;
}