score: Add thread priority to scheduler nodes

The thread priority is manifest in two independent areas.  One area is
the user visible thread priority along with a potential thread queue.
The other is the scheduler.  Currently, a thread priority update via
_Thread_Change_priority() first updates the user visble thread priority
and the thread queue, then the scheduler is notified if necessary.  The
priority is passed to the scheduler via a local variable.  A generation
counter ensures that the scheduler discards out-of-date priorities.

This use of a local variable ties the update in these two areas close
together.  For later enhancements and the OMIP locking protocol
implementation we need more flexibility.  Add a thread priority
information block to Scheduler_Node and synchronize priority value
updates via a sequence lock on SMP configurations.

Update #2556.

1 files changed, 20 insertions, 8 deletions

diff --git a/cpukit/score/src/schedulerpriorityunblock.c b/cpukit/score/src/schedulerpriorityunblock.c
index a912ebfbe2..ba8501bc50 100644
--- a/cpukit/score/src/schedulerpriorityunblock.c
+++ b/cpukit/score/src/schedulerpriorityunblock.c
@@ -27,9 +27,24 @@ Scheduler_Void_or_thread _Scheduler_priority_Unblock (
   Thread_Control          *the_thread
 )
 {
-  Scheduler_priority_Context *context =
-    _Scheduler_priority_Get_context( scheduler );
-  Scheduler_priority_Node *node = _Scheduler_priority_Thread_get_node( the_thread );
+  Scheduler_priority_Context *context;
+  Scheduler_priority_Node    *node;
+  unsigned int                priority;
+  bool                        prepend_it;
+
+  context = _Scheduler_priority_Get_context( scheduler );
+  node = _Scheduler_priority_Thread_get_node( the_thread );
+  priority = _Scheduler_Node_get_priority( &node->Base, &prepend_it );
+  (void) prepend_it;
+
+  if ( priority != node->Ready_queue.current_priority ) {
+    _Scheduler_priority_Ready_queue_update(
+      &node->Ready_queue,
+      priority,
+      &context->Bit_map,
+      &context->Ready[ 0 ]
+    );
+  }
 
   _Scheduler_priority_Ready_queue_enqueue(
     &the_thread->Object.Node,
@@ -51,11 +66,8 @@ Scheduler_Void_or_thread _Scheduler_priority_Unblock (
    *    Even if the thread isn't preemptible, if the new heir is
    *    a pseudo-ISR system task, we need to do a context switch.
    */
-  if ( the_thread->current_priority < _Thread_Heir->current_priority ) {
-    _Scheduler_Update_heir(
-      the_thread,
-      the_thread->current_priority == PRIORITY_PSEUDO_ISR
-    );
+  if ( priority < _Thread_Heir->current_priority ) {
+    _Scheduler_Update_heir( the_thread, priority == PRIORITY_PSEUDO_ISR );
   }
 
   SCHEDULER_RETURN_VOID_OR_NULL;