xref: /relibc/pthreads-emb/pthread_mutex_unlock.c (revision 0fd936b4d47ea5e32c07d38d2b38789a5b995eef)

/*
 * pthread_mutex_unlock.c
 *
 * Description:
 * This translation unit implements mutual exclusion (mutex) primitives.
 *
 * --------------------------------------------------------------------------
 *
 *      Pthreads-embedded (PTE) - POSIX Threads Library for embedded systems
 *      Copyright(C) 2008 Jason Schmidlapp
 *
 *      Contact Email: jschmidlapp@users.sourceforge.net
 *
 *
 *      Based upon Pthreads-win32 - POSIX Threads Library for Win32
 *      Copyright(C) 1998 John E. Bossom
 *      Copyright(C) 1999,2005 Pthreads-win32 contributors
 *
 *      Contact Email: rpj@callisto.canberra.edu.au
 *
 *      The original list of contributors to the Pthreads-win32 project
 *      is contained in the file CONTRIBUTORS.ptw32 included with the
 *      source code distribution. The list can also be seen at the
 *      following World Wide Web location:
 *      http://sources.redhat.com/pthreads-win32/contributors.html
 *
 *      This library is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU Lesser General Public
 *      License as published by the Free Software Foundation; either
 *      version 2 of the License, or (at your option) any later version.
 *
 *      This library is distributed in the hope that it will be useful,
 *      but WITHOUT ANY WARRANTY; without even the implied warranty of
 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *      Lesser General Public License for more details.
 *
 *      You should have received a copy of the GNU Lesser General Public
 *      License along with this library in the file COPYING.LIB;
 *      if not, write to the Free Software Foundation, Inc.,
 *      59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */

#include <pte_osal.h>

#include <stdio.h>
#include <stdlib.h>

#include "pthread.h"
#include "implement.h"


#define TEST_IE InterlockedExchange

int
pthread_mutex_unlock (pthread_mutex_t * mutex)
{
  int result = 0;
  pthread_mutex_t mx;

  /*
   * Let the system deal with invalid pointers.
   */
  if (*mutex == NULL)
    {
      return EINVAL;
    }

  mx = *mutex;

  /*
   * If the thread calling us holds the mutex then there is no
   * race condition. If another thread holds the
   * lock then we shouldn't be in here.
   */
  if (mx < PTHREAD_ERRORCHECK_MUTEX_INITIALIZER)
    {
      if (mx->kind == PTHREAD_MUTEX_NORMAL)
        {
          int idx;

          idx = PTE_ATOMIC_EXCHANGE (&mx->lock_idx,0);
          if (idx != 0)
            {
              if (idx < 0)
                {
                  /*
                   * Someone may be waiting on that mutex.
                   */
                  if (pte_osSemaphorePost(mx->handle,1) != PTE_OS_OK)
                    {
                      result = EINVAL;
                    }
                }
            }
          else
            {
              /*
               * Was not locked (so can't be owned by us).
               */
              result = EPERM;
            }
        }
      else
        {
          if (pthread_equal (mx->ownerThread, pthread_self ()))
            {
              if (mx->kind != PTHREAD_MUTEX_RECURSIVE
                  || 0 == --mx->recursive_count)
                {
                  mx->ownerThread = NULL;

                  if (PTE_ATOMIC_EXCHANGE (&mx->lock_idx,0) < 0)
                    {
                      if (pte_osSemaphorePost(mx->handle,1) != PTE_OS_OK)
                        {
                          result = EINVAL;
                        }

                    }
                }
            }
          else
            {
              result = EPERM;
            }
        }
    }
  else
    {
      result = EINVAL;
    }

  return (result);
}