/* * Mutex Handler * * DESCRIPTION: * * This package is the implementation of the Mutex Handler. * This handler provides synchronization and mutual exclusion capabilities. * * COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994. * On-Line Applications Research Corporation (OAR). * All rights assigned to U.S. Government, 1994. * * This material may be reproduced by or for the U.S. Government pursuant * to the copyright license under the clause at DFARS 252.227-7013. This * notice must appear in all copies of this file and its derivatives. * * $Id$ */ #include #include #include #include #include #include /*PAGE * * _CORE_mutex_Initialize * * This routine initializes a mutex at create time and set the control * structure according to the values passed. * * Input parameters: * the_mutex - the mutex control block to initialize * the_class - the API class of the object * the_mutex_attributes - the mutex attributes specified at create time * initial_lock - mutex initial lock or unlocked status * proxy_extract_callout - MP specific extract callout * * Output parameters: NONE */ void _CORE_mutex_Initialize( CORE_mutex_Control *the_mutex, Objects_Classes the_class, CORE_mutex_Attributes *the_mutex_attributes, unsigned32 initial_lock, Thread_queue_Extract_callout proxy_extract_callout ) { /* Add this to the RTEMS environment later ????????? rtems_assert( initial_lock == CORE_MUTEX_LOCKED || initial_lock == CORE_MUTEX_UNLOCKED ); */ the_mutex->Attributes = *the_mutex_attributes; the_mutex->lock = initial_lock; if ( initial_lock == CORE_MUTEX_LOCKED ) { the_mutex->nest_count = 1; the_mutex->holder = _Thread_Executing; the_mutex->holder_id = _Thread_Executing->Object.id; _Thread_Executing->resource_count++; } else { the_mutex->nest_count = 0; the_mutex->holder = NULL; the_mutex->holder_id = 0; } _Thread_queue_Initialize( &the_mutex->Wait_queue, the_class, _CORE_mutex_Is_priority( the_mutex_attributes ) ? THREAD_QUEUE_DISCIPLINE_PRIORITY : THREAD_QUEUE_DISCIPLINE_FIFO, STATES_WAITING_FOR_MUTEX, proxy_extract_callout, CORE_MUTEX_TIMEOUT ); } /*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; 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 ); return; } if ( _Objects_Are_ids_equal( _Thread_Executing->Object.id, the_mutex->holder_id ) ) { if ( _CORE_mutex_Is_nesting_allowed( &the_mutex->Attributes ) ) the_mutex->nest_count++; else executing->Wait.return_code = CORE_MUTEX_STATUS_NESTING_NOT_ALLOWED; _ISR_Enable( level ); return; } 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 ); if ( _CORE_mutex_Is_inherit_priority( &the_mutex->Attributes ) && the_mutex->holder->current_priority > _Thread_Executing->current_priority ) { _Thread_Change_priority( the_mutex->holder, _Thread_Executing->current_priority ); } _Thread_queue_Enqueue( &the_mutex->Wait_queue, timeout ); } /* * _CORE_mutex_Surrender * * DESCRIPTION: * * This routine frees a unit to the mutex. If a task was blocked waiting for * a unit from this mutex, then that task will be readied and the unit * given to that task. Otherwise, the unit will be returned to the mutex. * * Input parameters: * the_mutex - the mutex to be flushed * id - id of parent mutex * api_mutex_mp_support - api dependent MP support actions * * Output parameters: * CORE_MUTEX_STATUS_SUCCESSFUL - if successful * core error code - if unsuccessful */ CORE_mutex_Status _CORE_mutex_Surrender( CORE_mutex_Control *the_mutex, Objects_Id id, CORE_mutex_API_mp_support_callout api_mutex_mp_support ) { Thread_Control *the_thread; if ( !_Objects_Are_ids_equal( _Thread_Executing->Object.id, the_mutex->holder_id ) ) return( CORE_MUTEX_STATUS_NOT_OWNER_OF_RESOURCE ); the_mutex->nest_count--; if ( the_mutex->nest_count != 0 ) return( CORE_MUTEX_STATUS_SUCCESSFUL ); _Thread_Executing->resource_count--; the_mutex->holder = NULL; the_mutex->holder_id = 0; /* * Whether or not someone is waiting for the mutex, an * inherited priority must be lowered if this is the last * mutex (i.e. resource) this task has. */ if ( _CORE_mutex_Is_inherit_priority( &the_mutex->Attributes ) && _Thread_Executing->resource_count == 0 && _Thread_Executing->real_priority != _Thread_Executing->current_priority ) { _Thread_Change_priority( _Thread_Executing, _Thread_Executing->real_priority ); } if ( ( the_thread = _Thread_queue_Dequeue( &the_mutex->Wait_queue ) ) ) { if ( !_Objects_Is_local_id( the_thread->Object.id ) ) { the_mutex->holder = NULL; the_mutex->holder_id = the_thread->Object.id; the_mutex->nest_count = 1; ( *api_mutex_mp_support)( the_thread, id ); } else { the_mutex->holder = the_thread; the_mutex->holder_id = the_thread->Object.id; the_thread->resource_count++; the_mutex->nest_count = 1; /* * No special action for priority inheritance because the_thread * is guaranteed to be the highest priority thread waiting for * the mutex. */ } } else the_mutex->lock = CORE_MUTEX_UNLOCKED; return( CORE_MUTEX_STATUS_SUCCESSFUL ); } /*PAGE * * _CORE_mutex_Flush * * This function a flushes the mutex's task wait queue. * * Input parameters: * the_mutex - the mutex to be flushed * remote_extract_callout - function to invoke remotely * status - status to pass to thread * * Output parameters: NONE */ void _CORE_mutex_Flush( CORE_mutex_Control *the_mutex, Thread_queue_Flush_callout remote_extract_callout, unsigned32 status ) { _Thread_queue_Flush( &the_mutex->Wait_queue, remote_extract_callout, status ); }