incubator-nuttx/sched/pthread/pthread_mutexdestroy.c

/****************************************************************************
 * sched/pthread/pthread_mutexdestroy.c
 *
 *   Copyright (C) 2007-2009, 2017 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 <nuttx/config.h>

#include <pthread.h>
#include <semaphore.h>
#include <signal.h>
#include <sched.h>
#include <errno.h>
#include <debug.h>

#include <nuttx/semaphore.h>

#include "pthread/pthread.h"

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

/****************************************************************************
 * Name: pthread_mutex_destroy
 *
 * Description:
 *   Destroy a mutex.
 *
 * Parameters:
 *   None
 *
 * Return Value:
 *   None
 *
 * Assumptions:
 *
 ****************************************************************************/

int pthread_mutex_destroy(FAR pthread_mutex_t *mutex)
{
  int ret = EINVAL;
  int status;

  sinfo("mutex=0x%p\n", mutex);
  DEBUGASSERT(mutex != NULL);

  if (mutex != NULL)
    {
      /* Make sure the semaphore is stable while we make the following checks */

      sched_lock();

      /* Is the mutex available? */

      if (mutex->pid >= 0)
        {
          DEBUGASSERT(mutex->pid != 0); /* < 0: available, >0 owned, ==0 error */

          /* No.. Verify that the PID still exists.  We may be destroying
           * the mutex after cancelling a pthread and the mutex may have
           * been in a bad state owned by the dead pthread.  NOTE: The
           * following behavior is unspecified for pthread_mutex_destroy()
           * (see pthread_mutex_consistent()).
           *
           * If the holding thread is still valid, then we should be able to
           * map its PID to the underlying TCB. That is what sched_gettcb()
           * does.
           */

          if (sched_gettcb(mutex->pid) == NULL)
            {
              /* The thread associated with the PID no longer exists */

              mutex->pid = -1;

              /* Reset the semaphore.  If threads are were on this
               * semaphore, then this will awakened them and make
               * destruction of the semaphore impossible here.
               */

              status = nxsem_reset((FAR sem_t *)&mutex->sem, 1);
              if (status < 0)
                {
                  ret = -status;
                }

              /* Check if the reset caused some other thread to lock the
               * mutex.
               */

              else if (mutex->pid != -1)
                {
                  /* Yes.. then we cannot destroy the mutex now. */

                  ret = EBUSY;
                }

              /* Destroy the underlying semaphore */

              else
                {
                  status = nxsem_destroy((FAR sem_t *)&mutex->sem);
                  ret = (status < 0) ? -status : OK;
                }
            }
          else
            {
              ret = EBUSY;
            }
        }
      else
        {
          /* Destroy the semaphore
           *
           * REVISIT:  What if there are threads waiting on the semaphore?
           * Perhaps this logic should all nxsem_reset() first?
           */

          status = nxsem_destroy((FAR sem_t *)&mutex->sem);
          ret = ((status < 0) ? -status : OK);
        }

      sched_unlock();
    }

  sinfo("Returning %d\n", ret);
  return ret;
}