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Diffstat (limited to 'cpukit/score/src/coremutex.c')
| -rw-r--r-- | cpukit/score/src/coremutex.c | 269 |
1 files changed, 269 insertions, 0 deletions
diff --git a/cpukit/score/src/coremutex.c b/cpukit/score/src/coremutex.c new file mode 100644 index 0000000000..ea2b5773e1 --- /dev/null +++ b/cpukit/score/src/coremutex.c @@ -0,0 +1,269 @@ +/* + * 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 <rtems/system.h> +#include <rtems/core/isr.h> +#include <rtems/core/coremutex.h> +#include <rtems/core/states.h> +#include <rtems/core/thread.h> +#include <rtems/core/threadq.h> + +/*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 ( !wait ) { + _ISR_Enable( level ); + executing->Wait.return_code = CORE_MUTEX_STATUS_UNSATISFIED_NOWAIT; + 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; + } + + the_mutex->Wait_queue.sync = TRUE; + 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 + ); + +} |