Thread_Control *_Thread_queue_Do_dequeue(
Thread_queue_Control *the_thread_queue,
const Thread_queue_Operations *operations
#if defined(RTEMS_MULTIPROCESSING)
,
Thread_queue_MP_callout mp_callout
#endif
)
{
Thread_queue_Context queue_context;
Thread_Control *the_thread;
_Thread_queue_Context_initialize( &queue_context );
_Thread_queue_Context_set_MP_callout( &queue_context, mp_callout );
_Thread_queue_Acquire( the_thread_queue, &queue_context );
the_thread = _Thread_queue_First_locked( the_thread_queue, operations );
if ( the_thread != NULL ) {
_Thread_queue_Extract_critical(
&the_thread_queue->Queue,
operations,
the_thread,
&queue_context
);
} else {
_Thread_queue_Release( the_thread_queue, &queue_context );
}
return the_thread;
}
void _Thread_queue_Flush(
Thread_queue_Control *the_thread_queue,
#if defined(RTEMS_MULTIPROCESSING)
Thread_queue_Flush_callout remote_extract_callout,
#else
Thread_queue_Flush_callout remote_extract_callout RTEMS_UNUSED,
#endif
uint32_t status
)
{
ISR_lock_Context lock_context;
Thread_Control *the_thread;
_Thread_queue_Acquire( the_thread_queue, &lock_context );
while ( (the_thread = _Thread_queue_First_locked( the_thread_queue ) ) ) {
#if defined(RTEMS_MULTIPROCESSING)
if ( _Objects_Is_local_id( the_thread->Object.id ) )
#endif
the_thread->Wait.return_code = status;
_Thread_queue_Extract_critical(
&the_thread_queue->Queue,
the_thread_queue->operations,
the_thread,
&lock_context
);
#if defined(RTEMS_MULTIPROCESSING)
if ( !_Objects_Is_local_id( the_thread->Object.id ) )
( *remote_extract_callout )( the_thread );
#endif
_Thread_queue_Acquire( the_thread_queue, &lock_context );
}
_Thread_queue_Release( the_thread_queue, &lock_context );
}
CORE_mutex_Status _CORE_mutex_Surrender(
CORE_mutex_Control *the_mutex,
#if defined(RTEMS_MULTIPROCESSING)
Objects_Id id,
CORE_mutex_API_mp_support_callout api_mutex_mp_support,
#else
Objects_Id id __attribute__((unused)),
CORE_mutex_API_mp_support_callout api_mutex_mp_support __attribute__((unused)),
#endif
ISR_lock_Context *lock_context
)
{
Thread_Control *the_thread;
Thread_Control *holder;
holder = the_mutex->holder;
/*
* The following code allows a thread (or ISR) other than the thread
* which acquired the mutex to release that mutex. This is only
* allowed when the mutex in quetion is FIFO or simple Priority
* discipline. But Priority Ceiling or Priority Inheritance mutexes
* must be released by the thread which acquired them.
*/
if ( the_mutex->Attributes.only_owner_release ) {
if ( !_Thread_Is_executing( holder ) ) {
_ISR_lock_ISR_enable( lock_context );
return CORE_MUTEX_STATUS_NOT_OWNER_OF_RESOURCE;
}
}
_Thread_queue_Acquire_critical( &the_mutex->Wait_queue, lock_context );
/* XXX already unlocked -- not right status */
if ( !the_mutex->nest_count ) {
_Thread_queue_Release( &the_mutex->Wait_queue, lock_context );
return CORE_MUTEX_STATUS_SUCCESSFUL;
}
the_mutex->nest_count--;
if ( the_mutex->nest_count != 0 ) {
/*
* All error checking is on the locking side, so if the lock was
* allowed to acquired multiple times, then we should just deal with
* that. The RTEMS_DEBUG is just a validation.
*/
#if defined(RTEMS_DEBUG)
switch ( the_mutex->Attributes.lock_nesting_behavior ) {
case CORE_MUTEX_NESTING_ACQUIRES:
_Thread_queue_Release( &the_mutex->Wait_queue, lock_context );
return CORE_MUTEX_STATUS_SUCCESSFUL;
#if defined(RTEMS_POSIX_API)
case CORE_MUTEX_NESTING_IS_ERROR:
/* should never occur */
_Thread_queue_Release( &the_mutex->Wait_queue, lock_context );
return CORE_MUTEX_STATUS_NESTING_NOT_ALLOWED;
#endif
case CORE_MUTEX_NESTING_BLOCKS:
/* Currently no API exercises this behavior. */
break;
}
#else
_Thread_queue_Release( &the_mutex->Wait_queue, lock_context );
/* must be CORE_MUTEX_NESTING_ACQUIRES or we wouldn't be here */
return CORE_MUTEX_STATUS_SUCCESSFUL;
#endif
}
/*
* Formally release the mutex before possibly transferring it to a
* blocked thread.
*/
if ( _CORE_mutex_Is_inherit_priority( &the_mutex->Attributes ) ||
_CORE_mutex_Is_priority_ceiling( &the_mutex->Attributes ) ) {
CORE_mutex_Status pop_status =
_CORE_mutex_Pop_priority( the_mutex, holder );
if ( pop_status != CORE_MUTEX_STATUS_SUCCESSFUL ) {
_Thread_queue_Release( &the_mutex->Wait_queue, lock_context );
return pop_status;
}
holder->resource_count--;
}
the_mutex->holder = NULL;
/*
* Now we check if another thread was waiting for this mutex. If so,
* transfer the mutex to that thread.
*/
if ( ( the_thread = _Thread_queue_First_locked( &the_mutex->Wait_queue ) ) ) {
/*
* We must extract the thread now since this will restore its default
* thread lock. This is necessary to avoid a deadlock in the
* _Thread_Change_priority() below due to a recursive thread queue lock
* acquire.
*/
_Thread_queue_Extract_locked( &the_mutex->Wait_queue, the_thread );
#if defined(RTEMS_MULTIPROCESSING)
_Thread_Dispatch_disable();
if ( _Objects_Is_local_id( the_thread->Object.id ) )
#endif
{
the_mutex->holder = the_thread;
the_mutex->nest_count = 1;
switch ( the_mutex->Attributes.discipline ) {
case CORE_MUTEX_DISCIPLINES_FIFO:
case CORE_MUTEX_DISCIPLINES_PRIORITY:
break;
case CORE_MUTEX_DISCIPLINES_PRIORITY_INHERIT:
_CORE_mutex_Push_priority( the_mutex, the_thread );
the_thread->resource_count++;
break;
case CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING:
_CORE_mutex_Push_priority( the_mutex, the_thread );
the_thread->resource_count++;
_Thread_Raise_priority(
the_thread,
the_mutex->Attributes.priority_ceiling
);
break;
}
}
_Thread_queue_Unblock_critical(
&the_mutex->Wait_queue,
the_thread,
lock_context
);
#if defined(RTEMS_MULTIPROCESSING)
if ( !_Objects_Is_local_id( the_thread->Object.id ) ) {
the_mutex->holder = NULL;
the_mutex->nest_count = 1;
( *api_mutex_mp_support)( the_thread, id );
}
_Thread_Dispatch_enable( _Per_CPU_Get() );
#endif
} else {
_Thread_queue_Release( &the_mutex->Wait_queue, lock_context );
}
/*
* 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 ( !_Thread_Owns_resources( holder ) ) {
/*
* Ensure that the holder resource count is visible to all other processors
* and that we read the latest priority restore hint.
*/
_Atomic_Fence( ATOMIC_ORDER_ACQ_REL );
if ( holder->priority_restore_hint ) {
Per_CPU_Control *cpu_self;
cpu_self = _Thread_Dispatch_disable();
_Thread_Restore_priority( holder );
_Thread_Dispatch_enable( cpu_self );
}
}
return CORE_MUTEX_STATUS_SUCCESSFUL;
}
void _CORE_RWLock_Obtain_for_reading(
CORE_RWLock_Control *the_rwlock,
Thread_Control *executing,
Objects_Id id,
bool wait,
Watchdog_Interval timeout,
CORE_RWLock_API_mp_support_callout api_rwlock_mp_support
)
{
ISR_lock_Context lock_context;
/*
* If unlocked, then OK to read.
* If locked for reading and no waiters, then OK to read.
* If any thread is waiting, then we wait.
*/
_Thread_queue_Acquire( &the_rwlock->Wait_queue, &lock_context );
switch ( the_rwlock->current_state ) {
case CORE_RWLOCK_UNLOCKED:
the_rwlock->current_state = CORE_RWLOCK_LOCKED_FOR_READING;
the_rwlock->number_of_readers += 1;
_Thread_queue_Release( &the_rwlock->Wait_queue, &lock_context );
executing->Wait.return_code = CORE_RWLOCK_SUCCESSFUL;
return;
case CORE_RWLOCK_LOCKED_FOR_READING: {
Thread_Control *waiter;
waiter = _Thread_queue_First_locked( &the_rwlock->Wait_queue );
if ( !waiter ) {
the_rwlock->number_of_readers += 1;
_Thread_queue_Release( &the_rwlock->Wait_queue, &lock_context );
executing->Wait.return_code = CORE_RWLOCK_SUCCESSFUL;
return;
}
break;
}
case CORE_RWLOCK_LOCKED_FOR_WRITING:
break;
}
/*
* If the thread is not willing to wait, then return immediately.
*/
if ( !wait ) {
_Thread_queue_Release( &the_rwlock->Wait_queue, &lock_context );
executing->Wait.return_code = CORE_RWLOCK_UNAVAILABLE;
return;
}
/*
* We need to wait to enter this critical section
*/
executing->Wait.id = id;
executing->Wait.option = CORE_RWLOCK_THREAD_WAITING_FOR_READ;
executing->Wait.return_code = CORE_RWLOCK_SUCCESSFUL;
_Thread_queue_Enqueue_critical(
&the_rwlock->Wait_queue,
executing,
STATES_WAITING_FOR_RWLOCK,
timeout,
CORE_RWLOCK_TIMEOUT,
&lock_context
);
/* return to API level so it can dispatch and we block */
}
