summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorSebastian Huber <sebastian.huber@embedded-brains.de>2021-09-23 07:35:09 +0200
committerSebastian Huber <sebastian.huber@embedded-brains.de>2021-10-01 13:18:16 +0200
commit82e221671315e975036bb5bd80c370609f1381d0 (patch)
tree8afad37f1796fa8c2045d4365af673abab1e2586
parent18c8a270c296addff87f96b8c248f27eba31c24f (diff)
downloadrtems-82e221671315e975036bb5bd80c370609f1381d0.tar.bz2
score: Avoid dead code in thread queue surrender
For uniprocessor configurations, this patch removes dead code in the _Thread_queue_Surrender() and _Thread_queue_Surrender_priority_ceiling() functions. Dead code is removed from _Thread_queue_Surrender_sticky().
-rw-r--r--cpukit/score/src/threadqenqueue.c79
1 files changed, 67 insertions, 12 deletions
diff --git a/cpukit/score/src/threadqenqueue.c b/cpukit/score/src/threadqenqueue.c
index 4b138ba4d1..1b8b82eab9 100644
--- a/cpukit/score/src/threadqenqueue.c
+++ b/cpukit/score/src/threadqenqueue.c
@@ -544,6 +544,16 @@ static bool _Thread_queue_MP_set_callout(
}
#endif
+static void _Thread_queue_Force_ready_again( Thread_Control *the_thread )
+{
+ /*
+ * We must set the wait flags under protection of the current thread lock,
+ * otherwise a _Thread_Timeout() running on another processor may interfere.
+ */
+ _Thread_Wait_flags_set( the_thread, THREAD_QUEUE_READY_AGAIN );
+ _Thread_Wait_restore_default( the_thread );
+}
+
static bool _Thread_queue_Make_ready_again( Thread_Control *the_thread )
{
bool success;
@@ -570,6 +580,45 @@ static bool _Thread_queue_Make_ready_again( Thread_Control *the_thread )
return unblock;
}
+/*
+ * This function is used instead of _Thread_queue_Make_ready_again() in
+ * _Thread_queue_Surrender() and _Thread_queue_Surrender_priority_ceiling()
+ * since only the previous owner thread is allowed to surrender the thread
+ * queue.
+ *
+ * In uniprocessor configurations, there is only one executing thread (in this
+ * case the previous owner), so the new owner thread must be fully blocked.
+ *
+ * In SMP configurations, the new owner may execute on another processor in
+ * parallel, so we have to use _Thread_queue_Make_ready_again().
+ */
+static bool _Thread_queue_Make_new_owner_ready_again( Thread_Control *new_owner )
+{
+#if defined(RTEMS_SMP)
+ return _Thread_queue_Make_ready_again( new_owner );
+#else
+ _Assert( _Thread_Wait_flags_get( new_owner ) == THREAD_QUEUE_BLOCKED );
+ _Thread_queue_Force_ready_again( new_owner );
+ return false;
+#endif
+}
+
+static void _Thread_queue_Unblock_new_owner_and_remove_timer(
+ Thread_queue_Queue *queue,
+ Thread_Control *new_owner,
+ bool unblock
+)
+{
+#if defined(RTEMS_SMP)
+ if ( unblock ) {
+ _Thread_Remove_timer_and_unblock( new_owner, queue );
+ }
+#else
+ (void) unblock;
+ _Thread_Remove_timer_and_unblock( new_owner, queue );
+#endif
+}
+
bool _Thread_queue_Extract_locked(
Thread_queue_Queue *queue,
const Thread_queue_Operations *operations,
@@ -673,7 +722,7 @@ void _Thread_queue_Surrender(
_Thread_Resource_count_increment( new_owner );
}
- unblock = _Thread_queue_Make_ready_again( new_owner );
+ unblock = _Thread_queue_Make_new_owner_ready_again( new_owner );
cpu_self = _Thread_queue_Dispatch_disable( queue_context );
_Thread_queue_Queue_release(
@@ -682,10 +731,11 @@ void _Thread_queue_Surrender(
);
_Thread_Priority_update( queue_context );
-
- if ( unblock ) {
- _Thread_Remove_timer_and_unblock( new_owner, queue );
- }
+ _Thread_queue_Unblock_new_owner_and_remove_timer(
+ queue,
+ new_owner,
+ unblock
+ );
_Thread_Dispatch_enable( cpu_self );
}
@@ -771,7 +821,7 @@ Status_Control _Thread_queue_Surrender_priority_ceiling(
queue->owner = new_owner;
- unblock = _Thread_queue_Make_ready_again( new_owner );
+ unblock = _Thread_queue_Make_new_owner_ready_again( new_owner );
#if defined(RTEMS_MULTIPROCESSING)
if ( _Objects_Is_local_id( new_owner->Object.id ) )
@@ -790,10 +840,11 @@ Status_Control _Thread_queue_Surrender_priority_ceiling(
);
_Thread_Priority_update( queue_context );
-
- if ( unblock ) {
- _Thread_Remove_timer_and_unblock( new_owner, queue );
- }
+ _Thread_queue_Unblock_new_owner_and_remove_timer(
+ queue,
+ new_owner,
+ unblock
+ );
_Thread_Dispatch_direct( cpu_self );
return STATUS_SUCCESSFUL;
@@ -823,11 +874,15 @@ void _Thread_queue_Surrender_sticky(
queue->owner = new_owner;
/*
- * There is no need to check the unblock status, since in the corresponding
+ * There is no need to unblock the thread, since in the corresponding
* _Thread_queue_Enqueue_sticky() the thread is not blocked by the scheduler.
* Instead, the thread busy waits for a change of its thread wait flags.
+ * Timeouts cannot interfere since we hold the thread queue lock.
*/
- (void) _Thread_queue_Make_ready_again( new_owner );
+ _Assert(
+ _Thread_Wait_flags_get( new_owner ) == THREAD_QUEUE_INTEND_TO_BLOCK
+ );
+ _Thread_queue_Force_ready_again( new_owner );
cpu_self = _Thread_queue_Dispatch_disable( queue_context );
_Thread_queue_Queue_release(