nuttx/sched/semaphore/sem_timeout.c

/****************************************************************************
 * sched/semaphore/sem_timeout.c
 *
 *   Copyright (C) 2011, 2013-2015 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
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 *
 ****************************************************************************/

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

#include <nuttx/config.h>

#include <errno.h>

#include <nuttx/sched.h>
#include <nuttx/wdog.h>

#include <nuttx/irq.h>

#include "semaphore/semaphore.h"

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

/****************************************************************************
 * Name: nxsem_timeout
 *
 * Description:
 *   This function is called if the timeout elapses before before a
 *   semaphore is acquired.
 *
 * Input Parameters:
 *   pid  - The task ID of the task to wakeup
 *
 * Returned Value:
 *   None
 *
 * Assumptions:
 *   - Called from the context of the timer interrupt handler.
 *
 ****************************************************************************/

void nxsem_timeout(wdparm_t pid)
{
  FAR struct tcb_s *wtcb;
  irqstate_t flags;

  /* Disable interrupts to avoid race conditions */

  flags = enter_critical_section();

  /* Get the TCB associated with this PID.  It is possible that
   * task may no longer be active when this watchdog goes off.
   */

  wtcb = nxsched_get_tcb(pid);

  /* It is also possible that an interrupt/context switch beat us to the
   * punch and already changed the task's state.
   */

  if (wtcb && wtcb->task_state == TSTATE_WAIT_SEM)
    {
      /* Cancel the semaphore wait */

      nxsem_wait_irq(wtcb, ETIMEDOUT);
    }

  /* Interrupts may now be enabled. */

  leave_critical_section(flags);
}