score: Simplify _Thread_Change_priority()

The function to change a thread priority was too complex.  Simplify it
with a new scheduler operation.  This increases the average case
performance due to the simplified logic.  The interrupt disabled
critical section is a bit prolonged since now the extract, update and
enqueue steps are executed atomically.  This should however not impact
the worst-case interrupt latency since at least for the Deterministic
Priority Scheduler this sequence can be carried out with a wee bit of
instructions and no loops.

Add _Scheduler_Change_priority() to replace the sequence of
  - _Thread_Set_transient(),
  - _Scheduler_Extract(),
  - _Scheduler_Enqueue(), and
  - _Scheduler_Enqueue_first().

Delete STATES_TRANSIENT, _States_Is_transient() and
_Thread_Set_transient() since this state is now superfluous.

With this change it is possible to get rid of the
SCHEDULER_SMP_NODE_IN_THE_AIR state.  This considerably simplifies the
implementation of the new SMP locking protocols.

1 files changed, 25 insertions, 0 deletions

diff --git a/cpukit/score/include/rtems/score/scheduleredfimpl.h b/cpukit/score/include/rtems/score/scheduleredfimpl.h
index 8c4cd2c4bd..d424370a45 100644
--- a/cpukit/score/include/rtems/score/scheduleredfimpl.h
+++ b/cpukit/score/include/rtems/score/scheduleredfimpl.h
@@ -44,6 +44,31 @@ RTEMS_INLINE_ROUTINE Scheduler_EDF_Node *_Scheduler_EDF_Node_get(
   return (Scheduler_EDF_Node *) _Scheduler_Node_get( the_thread );
 }
 
+RTEMS_INLINE_ROUTINE void _Scheduler_EDF_Enqueue(
+  const Scheduler_Control *scheduler,
+  Thread_Control          *the_thread
+)
+{
+  Scheduler_EDF_Context *context =
+    _Scheduler_EDF_Get_context( scheduler );
+  Scheduler_EDF_Node *node = _Scheduler_EDF_Node_get( the_thread );
+
+  _RBTree_Insert( &context->Ready, &node->Node );
+  node->queue_state = SCHEDULER_EDF_QUEUE_STATE_YES;
+}
+
+RTEMS_INLINE_ROUTINE void _Scheduler_EDF_Extract(
+  const Scheduler_Control *scheduler,
+  Thread_Control          *the_thread
+)
+{
+  Scheduler_EDF_Context *context =
+    _Scheduler_EDF_Get_context( scheduler );
+  Scheduler_EDF_Node *node = _Scheduler_EDF_Node_get( the_thread );
+
+  _RBTree_Extract( &context->Ready, &node->Node );
+}
+
 RTEMS_INLINE_ROUTINE void _Scheduler_EDF_Schedule_body(
   const Scheduler_Control *scheduler,
   Thread_Control          *the_thread,