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/*
* Mutex Handler
*
* DESCRIPTION:
*
* This package is the implementation of the Mutex Handler.
* This handler provides synchronization and mutual exclusion capabilities.
*
* COPYRIGHT (c) 1989-1999.
* 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.OARcorp.com/rtems/license.html.
*
* $Id$
*/
#include <rtems/system.h>
#include <rtems/score/isr.h>
#include <rtems/score/coremutex.h>
#include <rtems/score/states.h>
#include <rtems/score/thread.h>
#include <rtems/score/threadq.h>
/*PAGE
*
* _CORE_mutex_Seize
*
* This routine attempts to allocate a mutex to the calling thread.
*
* Input parameters:
* the_mutex - pointer to mutex control block
* id - id of object to wait on
* wait - TRUE if wait is allowed, FALSE otherwise
* timeout - number of ticks to wait (0 means forever)
*
* Output parameters: NONE
*
* INTERRUPT LATENCY:
* available
* wait
*/
void _CORE_mutex_Seize(
CORE_mutex_Control *the_mutex,
Objects_Id id,
boolean wait,
Watchdog_Interval timeout
)
{
Thread_Control *executing;
ISR_Level level;
executing = _Thread_Executing;
switch ( the_mutex->Attributes.discipline ) {
case CORE_MUTEX_DISCIPLINES_FIFO:
case CORE_MUTEX_DISCIPLINES_PRIORITY:
case CORE_MUTEX_DISCIPLINES_PRIORITY_INHERIT:
break;
case CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING:
if ( executing->current_priority <
the_mutex->Attributes.priority_ceiling) {
executing->Wait.return_code = CORE_MUTEX_STATUS_CEILING_VIOLATED;
return;
}
}
executing->Wait.return_code = CORE_MUTEX_STATUS_SUCCESSFUL;
_ISR_Disable( level );
if ( ! _CORE_mutex_Is_locked( the_mutex ) ) {
the_mutex->lock = CORE_MUTEX_LOCKED;
the_mutex->holder = executing;
the_mutex->holder_id = executing->Object.id;
the_mutex->nest_count = 1;
executing->resource_count++;
_ISR_Enable( level );
switch ( the_mutex->Attributes.discipline ) {
case CORE_MUTEX_DISCIPLINES_FIFO:
case CORE_MUTEX_DISCIPLINES_PRIORITY:
case CORE_MUTEX_DISCIPLINES_PRIORITY_INHERIT:
/* already the highest priority */
break;
case CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING:
if ( the_mutex->Attributes.priority_ceiling <
executing->current_priority ) {
_Thread_Change_priority(
the_mutex->holder,
the_mutex->Attributes.priority_ceiling,
FALSE
);
}
}
executing->Wait.return_code = CORE_MUTEX_STATUS_SUCCESSFUL;
return;
}
if ( _Thread_Is_executing( the_mutex->holder ) ) {
switch ( the_mutex->Attributes.lock_nesting_behavior ) {
case CORE_MUTEX_NESTING_ACQUIRES:
the_mutex->nest_count++;
_ISR_Enable( level );
return;
case CORE_MUTEX_NESTING_IS_ERROR:
executing->Wait.return_code = CORE_MUTEX_STATUS_NESTING_NOT_ALLOWED;
_ISR_Enable( level );
return;
case CORE_MUTEX_NESTING_BLOCKS:
break;
}
}
if ( !wait ) {
_ISR_Enable( level );
executing->Wait.return_code = CORE_MUTEX_STATUS_UNSATISFIED_NOWAIT;
return;
}
_Thread_queue_Enter_critical_section( &the_mutex->Wait_queue );
executing->Wait.queue = &the_mutex->Wait_queue;
executing->Wait.id = id;
_ISR_Enable( level );
switch ( the_mutex->Attributes.discipline ) {
case CORE_MUTEX_DISCIPLINES_FIFO:
case CORE_MUTEX_DISCIPLINES_PRIORITY:
case CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING:
break;
case CORE_MUTEX_DISCIPLINES_PRIORITY_INHERIT:
if ( the_mutex->holder->current_priority > executing->current_priority ) {
_Thread_Change_priority(
the_mutex->holder,
executing->current_priority,
FALSE
);
}
break;
}
_Thread_queue_Enqueue( &the_mutex->Wait_queue, timeout );
if ( _Thread_Executing->Wait.return_code == CORE_MUTEX_STATUS_SUCCESSFUL ) {
switch ( the_mutex->Attributes.discipline ) {
case CORE_MUTEX_DISCIPLINES_FIFO:
case CORE_MUTEX_DISCIPLINES_PRIORITY:
case CORE_MUTEX_DISCIPLINES_PRIORITY_INHERIT:
break;
case CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING:
if ( the_mutex->Attributes.priority_ceiling <
executing->current_priority ) {
_Thread_Change_priority(
executing,
the_mutex->Attributes.priority_ceiling,
FALSE
);
};
break;
}
}
}
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