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[/] [openrisc/] [trunk/] [rtos/] [rtems/] [c/] [src/] [exec/] [score/] [src/] [coremutexseize.c] - Blame information for rev 773

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1 30 unneback 
/*
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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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 *  $Id: coremutexseize.c,v 1.2 2001-09-27 11:59:34 chris 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
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 *
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 *  This routine attempts to allocate a mutex to the calling thread.
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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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 *    id        - id of object to wait on
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 *    wait      - TRUE if wait is allowed, FALSE otherwise
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 *    timeout   - number of ticks to wait (0 means forever)
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 *
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 *  Output parameters:  NONE
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 *
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 *  INTERRUPT LATENCY:
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 *    available
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 *    wait
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 */
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void _CORE_mutex_Seize(
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  CORE_mutex_Control  *the_mutex,
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  Objects_Id           id,
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  boolean              wait,
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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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  ISR_Level       level;
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  executing = _Thread_Executing;
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  switch ( the_mutex->Attributes.discipline ) {
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    case CORE_MUTEX_DISCIPLINES_FIFO:
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    case CORE_MUTEX_DISCIPLINES_PRIORITY:
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    case CORE_MUTEX_DISCIPLINES_PRIORITY_INHERIT:
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      break;
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    case CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING:
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      if ( executing->current_priority <
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                              the_mutex->Attributes.priority_ceiling) {
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        executing->Wait.return_code = CORE_MUTEX_STATUS_CEILING_VIOLATED;
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        return;
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      }
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  }
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  executing->Wait.return_code = CORE_MUTEX_STATUS_SUCCESSFUL;
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  _ISR_Disable( level );
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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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    executing->resource_count++;
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    _ISR_Enable( level );
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    switch ( the_mutex->Attributes.discipline ) {
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      case CORE_MUTEX_DISCIPLINES_FIFO:
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      case CORE_MUTEX_DISCIPLINES_PRIORITY:
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      case CORE_MUTEX_DISCIPLINES_PRIORITY_INHERIT:
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        /* already the highest priority */
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        break;
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      case CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING:
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      if ( the_mutex->Attributes.priority_ceiling <
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                                           executing->current_priority ) {
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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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      }
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    }
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    executing->Wait.return_code = CORE_MUTEX_STATUS_SUCCESSFUL;
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    return;
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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;
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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;
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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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  if ( !wait ) {
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    _ISR_Enable( level );
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    executing->Wait.return_code = CORE_MUTEX_STATUS_UNSATISFIED_NOWAIT;
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    return;
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  }
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  _Thread_queue_Enter_critical_section( &the_mutex->Wait_queue );
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  executing->Wait.queue = &the_mutex->Wait_queue;
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  executing->Wait.id    = id;
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  _ISR_Enable( level );
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  switch ( the_mutex->Attributes.discipline ) {
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    case CORE_MUTEX_DISCIPLINES_FIFO:
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    case CORE_MUTEX_DISCIPLINES_PRIORITY:
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    case CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING:
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      break;
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    case CORE_MUTEX_DISCIPLINES_PRIORITY_INHERIT:
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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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      break;
137 
  }
138 
 
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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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    switch ( the_mutex->Attributes.discipline ) {
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      case CORE_MUTEX_DISCIPLINES_FIFO:
144 
      case CORE_MUTEX_DISCIPLINES_PRIORITY:
145 
      case CORE_MUTEX_DISCIPLINES_PRIORITY_INHERIT:
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        break;
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      case CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING:
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        if ( the_mutex->Attributes.priority_ceiling <
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                                           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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        break;
157 
    }
158 
  }
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}
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