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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.rtems.com/license/LICENSE.
*
* $Id$
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#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 (interrupt blocking support)
*
* This routine blocks the caller thread after an attempt attempts to obtain
* the specified mutex has failed.
*
* Input parameters:
* the_mutex - pointer to mutex control block
* timeout - number of ticks to wait (0 means forever)
*/
void _CORE_mutex_Seize_interrupt_blocking(
CORE_mutex_Control *the_mutex,
Watchdog_Interval timeout
)
{
Thread_Control *executing;
executing = _Thread_Executing;
if ( _CORE_mutex_Is_inherit_priority( &the_mutex->Attributes ) ) {
if ( the_mutex->holder->current_priority > executing->current_priority ) {
_Thread_Change_priority(
the_mutex->holder,
executing->current_priority,
FALSE
);
}
}
the_mutex->blocked_count++;
_Thread_queue_Enqueue( &the_mutex->Wait_queue, timeout );
if ( _Thread_Executing->Wait.return_code == CORE_MUTEX_STATUS_SUCCESSFUL ) {
/*
* if CORE_MUTEX_DISCIPLINES_PRIORITY_INHERIT then nothing to do
* because this task is already the highest priority.
*/
if ( _CORE_mutex_Is_priority_ceiling( &the_mutex->Attributes ) ) {
if (the_mutex->Attributes.priority_ceiling < executing->current_priority){
_Thread_Change_priority(
executing,
the_mutex->Attributes.priority_ceiling,
FALSE
);
}
}
}
_Thread_Enable_dispatch();
}
#if !defined(RTEMS_INLINES)
int _CORE_mutex_Seize_interrupt_trylock(
CORE_mutex_Control *the_mutex,
ISR_Level *level_p
)
{
Thread_Control *executing;
ISR_Level level = *level_p;
/* disabled when you get here */
executing = _Thread_Executing;
executing->Wait.return_code = CORE_MUTEX_STATUS_SUCCESSFUL;
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;
if ( _CORE_mutex_Is_inherit_priority( &the_mutex->Attributes ) ||
_CORE_mutex_Is_priority_ceiling( &the_mutex->Attributes ) )
executing->resource_count++;
if ( !_CORE_mutex_Is_priority_ceiling( &the_mutex->Attributes ) ) {
_ISR_Enable( level );
return 0;
}
/* else must be CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING */
{
Priority_Control ceiling;
Priority_Control current;
ceiling = the_mutex->Attributes.priority_ceiling;
current = executing->current_priority;
if ( current == ceiling ) {
_ISR_Enable( level );
return 0;
}
if ( current > ceiling ) {
_Thread_Disable_dispatch();
_ISR_Enable( level );
_Thread_Change_priority(
the_mutex->holder,
the_mutex->Attributes.priority_ceiling,
FALSE
);
_Thread_Enable_dispatch();
return 0;
}
/* if ( current < ceiling ) */ {
executing->Wait.return_code = CORE_MUTEX_STATUS_CEILING_VIOLATED;
the_mutex->nest_count = 0; /* undo locking above */
executing->resource_count--; /* undo locking above */
_ISR_Enable( level );
return 0;
}
}
return 0;
}
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 0;
case CORE_MUTEX_NESTING_IS_ERROR:
executing->Wait.return_code = CORE_MUTEX_STATUS_NESTING_NOT_ALLOWED;
_ISR_Enable( level );
return 0;
case CORE_MUTEX_NESTING_BLOCKS:
break;
}
}
return 1;
}
#endif
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