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counter ensures that the scheduler discards out-of-date priorities.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, 3 insertions, 1 deletions

diff --git a/cpukit/score/src/schedulercbsunblock.c b/cpukit/score/src/schedulercbsunblock.c
index 3f5bd33623..70db651080 100644
--- a/cpukit/score/src/schedulercbsunblock.c
+++ b/cpukit/score/src/schedulercbsunblock.c
@@ -34,11 +34,13 @@ Scheduler_Void_or_thread _Scheduler_CBS_Unblock(
   Scheduler_CBS_Node    *node;
   Scheduler_CBS_Server  *serv_info;
   Priority_Control       priority;
+  bool                   prepend_it;
 
   context = _Scheduler_EDF_Get_context( scheduler );
   node = _Scheduler_CBS_Thread_get_node( the_thread );
   serv_info = node->cbs_server;
-  priority = node->Base.current_priority;
+  priority = _Scheduler_Node_get_priority( &node->Base.Base, &prepend_it );
+  (void) prepend_it;
 
   /*
    * Late unblock rule for deadline-driven tasks. The remaining time to