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/*
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* Mutex Handler
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*
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* DESCRIPTION:
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*
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* This package is the implementation of the Mutex Handler.
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* This handler provides synchronization and mutual exclusion capabilities.
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*
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* COPYRIGHT (c) 1989-1999.
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* On-Line Applications Research Corporation (OAR).
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*
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* The license and distribution terms for this file may be
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* found in the file LICENSE in this distribution or at
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* http://www.OARcorp.com/rtems/license.html.
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*
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* coremutexseize.c,v 1.7 2001/08/30 18:33:57 joel Exp
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*/
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#include <rtems/system.h>
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#include <rtems/score/isr.h>
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#include <rtems/score/coremutex.h>
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#include <rtems/score/states.h>
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#include <rtems/score/thread.h>
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#include <rtems/score/threadq.h>
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/*PAGE
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*
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* _CORE_mutex_Seize (interrupt blocking support)
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*
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* This routine blocks the caller thread after an attempt attempts to obtain
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* the specified mutex has failed.
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*
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* Input parameters:
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* the_mutex - pointer to mutex control block
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* timeout - number of ticks to wait (0 means forever)
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*/
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void _CORE_mutex_Seize_interrupt_blocking(
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CORE_mutex_Control *the_mutex,
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Watchdog_Interval timeout
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)
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{
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Thread_Control *executing;
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executing = _Thread_Executing;
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if ( _CORE_mutex_Is_inherit_priority( &the_mutex->Attributes ) ) {
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if ( the_mutex->holder->current_priority > executing->current_priority ) {
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_Thread_Change_priority(
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the_mutex->holder,
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executing->current_priority,
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FALSE
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);
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}
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}
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the_mutex->blocked_count++;
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_Thread_queue_Enqueue( &the_mutex->Wait_queue, timeout );
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if ( _Thread_Executing->Wait.return_code == CORE_MUTEX_STATUS_SUCCESSFUL ) {
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/*
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* if CORE_MUTEX_DISCIPLINES_PRIORITY_INHERIT then nothing to do
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* because this task is already the highest priority.
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*/
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if ( _CORE_mutex_Is_priority_ceiling( &the_mutex->Attributes ) ) {
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if (the_mutex->Attributes.priority_ceiling < executing->current_priority){
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_Thread_Change_priority(
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executing,
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the_mutex->Attributes.priority_ceiling,
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FALSE
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);
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}
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}
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}
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_Thread_Enable_dispatch();
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}
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#if !defined(USE_INLINES)
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int _CORE_mutex_Seize_interrupt_trylock(
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CORE_mutex_Control *the_mutex,
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ISR_Level *level_p
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)
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{
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Thread_Control *executing;
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ISR_Level level = *level_p;
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/* disabled when you get here */
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executing = _Thread_Executing;
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executing->Wait.return_code = CORE_MUTEX_STATUS_SUCCESSFUL;
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if ( !_CORE_mutex_Is_locked( the_mutex ) ) {
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the_mutex->lock = CORE_MUTEX_LOCKED;
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the_mutex->holder = executing;
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the_mutex->holder_id = executing->Object.id;
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the_mutex->nest_count = 1;
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if ( _CORE_mutex_Is_inherit_priority( &the_mutex->Attributes ) ||
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_CORE_mutex_Is_priority_ceiling( &the_mutex->Attributes ) )
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executing->resource_count++;
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if ( !_CORE_mutex_Is_priority_ceiling( &the_mutex->Attributes ) ) {
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_ISR_Enable( level );
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return 0;
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}
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/* else must be CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING */
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{
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Priority_Control ceiling;
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Priority_Control current;
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ceiling = the_mutex->Attributes.priority_ceiling;
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current = executing->current_priority;
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if ( current == ceiling ) {
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_ISR_Enable( level );
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return 0;
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}
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if ( current > ceiling ) {
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_Thread_Disable_dispatch();
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_ISR_Enable( level );
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_Thread_Change_priority(
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the_mutex->holder,
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the_mutex->Attributes.priority_ceiling,
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FALSE
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);
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_Thread_Enable_dispatch();
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return 0;
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}
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/* if ( current < ceiling ) */ {
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executing->Wait.return_code = CORE_MUTEX_STATUS_CEILING_VIOLATED;
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the_mutex->nest_count = 0; /* undo locking above */
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executing->resource_count--; /* undo locking above */
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_ISR_Enable( level );
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return 0;
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}
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}
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return 0;
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}
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if ( _Thread_Is_executing( the_mutex->holder ) ) {
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switch ( the_mutex->Attributes.lock_nesting_behavior ) {
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case CORE_MUTEX_NESTING_ACQUIRES:
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the_mutex->nest_count++;
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_ISR_Enable( level );
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return 0;
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case CORE_MUTEX_NESTING_IS_ERROR:
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executing->Wait.return_code = CORE_MUTEX_STATUS_NESTING_NOT_ALLOWED;
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_ISR_Enable( level );
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return 0;
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case CORE_MUTEX_NESTING_BLOCKS:
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break;
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}
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}
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return 1;
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}
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#endif
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