/*
* 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/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_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;
}
_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
);
}
