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pthread_mutex_lock.c
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pthread_mutex_lock.c
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/*
* pthread_mutex_lock.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: [email protected]
*
*
* Based upon Pthreads-win32 - POSIX Threads Library for Win32
* Copyright(C) 1998 John E. Bossom
* Copyright(C) 1999,2005 Pthreads-win32 contributors
*
* Contact Email: [email protected]
*
* 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 <stdio.h>
#include <stdlib.h>
#include "pthread.h"
#include "implement.h"
int
pthread_mutex_lock (pthread_mutex_t * mutex)
{
int result = 0;
pthread_mutex_t mx;
/*
* Let the system deal with invalid pointers.
*/
if (*mutex == NULL)
{
return EINVAL;
}
/*
* We do a quick check to see if we need to do more work
* to initialise a static mutex. We check
* again inside the guarded section of pte_mutex_check_need_init()
* to avoid race conditions.
*/
if (*mutex >= PTHREAD_ERRORCHECK_MUTEX_INITIALIZER)
{
if ((result = pte_mutex_check_need_init (mutex)) != 0)
{
return (result);
}
}
mx = *mutex;
if (mx->kind == PTHREAD_MUTEX_NORMAL)
{
if (PTE_ATOMIC_EXCHANGE(
&mx->lock_idx,
1) != 0)
{
while (PTE_ATOMIC_EXCHANGE(&mx->lock_idx,-1) != 0)
{
if (pte_osSemaphorePend(mx->handle,NULL) != PTE_OS_OK)
{
result = EINVAL;
break;
}
}
}
}
else
{
pthread_t self = pthread_self();
if (PTE_ATOMIC_COMPARE_EXCHANGE(&mx->lock_idx,1,0) == 0)
{
mx->recursive_count = 1;
mx->ownerThread = self;
}
else
{
if (pthread_equal (mx->ownerThread, self))
{
if (mx->kind == PTHREAD_MUTEX_RECURSIVE)
{
mx->recursive_count++;
}
else
{
result = EDEADLK;
}
}
else
{
while (PTE_ATOMIC_EXCHANGE(&mx->lock_idx,-1) != 0)
{
if (pte_osSemaphorePend(mx->handle,NULL) != PTE_OS_OK)
{
result = EINVAL;
break;
}
}
if (0 == result)
{
mx->recursive_count = 1;
mx->ownerThread = self;
}
}
}
}
return (result);
}