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/**
* @file
*
* @brief Initialize a Mutex
* @ingroup POSIXAPI
*/
/*
* COPYRIGHT (c) 1989-2009.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <rtems/posix/muteximpl.h>
#include <rtems/posix/priorityimpl.h>
#include <rtems/score/schedulerimpl.h>
/**
* 11.3.2 Initializing and Destroying a Mutex, P1003.1c/Draft 10, p. 87
*
* NOTE: XXX Could be optimized so all the attribute error checking
* is not performed when attr is NULL.
*/
int pthread_mutex_init(
pthread_mutex_t *mutex,
const pthread_mutexattr_t *attr
)
{
POSIX_Mutex_Control *the_mutex;
const pthread_mutexattr_t *the_attr;
POSIX_Mutex_Protocol protocol;
const Scheduler_Control *scheduler;
Priority_Control priority;
if ( attr ) the_attr = attr;
else the_attr = &_POSIX_Mutex_Default_attributes;
/* Check for NULL mutex */
if ( !mutex )
return EINVAL;
/*
* The POSIX specification says:
*
* "Attempting to initialize an already initialized mutex results
* in undefined behavior."
*
* Trying to keep the caller from doing the create when *mutex
* is actually a valid ID causes grief. All it takes is the wrong
* value in an uninitialized variable to make this fail.
*
* Thus, we do not look at *mutex.
*/
if ( !the_attr->is_initialized )
return EINVAL;
/*
* We only support process private mutexes.
*/
if ( the_attr->process_shared == PTHREAD_PROCESS_SHARED )
return ENOSYS;
if ( the_attr->process_shared != PTHREAD_PROCESS_PRIVATE )
return EINVAL;
/*
* Determine the discipline of the mutex
*/
switch ( the_attr->protocol ) {
case PTHREAD_PRIO_NONE:
protocol = POSIX_MUTEX_NO_PROTOCOL;
break;
case PTHREAD_PRIO_INHERIT:
protocol = POSIX_MUTEX_PRIORITY_INHERIT;
break;
case PTHREAD_PRIO_PROTECT:
protocol = POSIX_MUTEX_PRIORITY_CEILING;
break;
default:
return EINVAL;
}
#if defined(_UNIX98_THREAD_MUTEX_ATTRIBUTES)
/*
* Validate the mutex type and set appropriate SuperCore mutex
* attributes.
*/
switch ( the_attr->type ) {
case PTHREAD_MUTEX_NORMAL:
case PTHREAD_MUTEX_RECURSIVE:
case PTHREAD_MUTEX_ERRORCHECK:
case PTHREAD_MUTEX_DEFAULT:
break;
default:
return EINVAL;
}
#endif
if ( protocol == POSIX_MUTEX_PRIORITY_CEILING ) {
int prio_ceiling;
bool valid;
scheduler = _Thread_Scheduler_get_home( _Thread_Get_executing() );
prio_ceiling = the_attr->prio_ceiling;
if ( prio_ceiling == INT_MAX ) {
prio_ceiling = _POSIX_Priority_Get_maximum( scheduler );
}
priority = _POSIX_Priority_To_core( scheduler, prio_ceiling, &valid );
if ( !valid ) {
return EINVAL;
}
}
the_mutex = _POSIX_Mutex_Allocate();
if ( !the_mutex ) {
_Objects_Allocator_unlock();
return EAGAIN;
}
the_mutex->protocol = protocol;
the_mutex->is_recursive = ( the_attr->type == PTHREAD_MUTEX_RECURSIVE );
switch ( protocol ) {
case POSIX_MUTEX_PRIORITY_CEILING:
_CORE_ceiling_mutex_Initialize( &the_mutex->Mutex, scheduler, priority );
break;
default:
_Assert(
the_mutex->protocol == POSIX_MUTEX_NO_PROTOCOL
|| the_mutex->protocol == POSIX_MUTEX_PRIORITY_INHERIT
);
_CORE_recursive_mutex_Initialize( &the_mutex->Mutex.Recursive );
break;
}
_Objects_Open_u32( &_POSIX_Mutex_Information, &the_mutex->Object, 0 );
*mutex = the_mutex->Object.id;
_Objects_Allocator_unlock();
return 0;
}
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