score: Rework thread priority management

Add priority nodes which contribute to the overall thread priority.

The actual priority of a thread is now an aggregation of priority nodes.
The thread priority aggregation for the home scheduler instance of a
thread consists of at least one priority node, which is normally the
real priority of the thread.  The locking protocols (e.g. priority
ceiling and priority inheritance), rate-monotonic period objects and the
POSIX sporadic server add, change and remove priority nodes.

A thread changes its priority now immediately, e.g. priority changes are
not deferred until the thread releases its last resource.

Replace the _Thread_Change_priority() function with

 * _Thread_Priority_perform_actions(),
 * _Thread_Priority_add(),
 * _Thread_Priority_remove(),
 * _Thread_Priority_change(), and
 * _Thread_Priority_update().

Update #2412.
Update #2556.

1 files changed, 2 insertions, 19 deletions

diff --git a/cpukit/score/include/rtems/score/schedulernode.h b/cpukit/score/include/rtems/score/schedulernode.h
index 293887c4b7..9827d21e64 100644
--- a/cpukit/score/include/rtems/score/schedulernode.h
+++ b/cpukit/score/include/rtems/score/schedulernode.h
@@ -98,7 +98,7 @@ typedef enum {
 /**
  * @brief Scheduler node for per-thread data.
  */
-typedef struct {
+typedef struct Scheduler_Node {
 #if defined(RTEMS_SMP)
   /**
    * @brief Chain node for usage in various scheduler data structures.
@@ -144,24 +144,7 @@ typedef struct {
    * @brief Thread wait support block.
    */
   struct {
-    /**
-     * @brief Node for thread queues.
-     *
-     * Each scheduler node can be enqueued on a thread queue on behalf of the
-     * thread owning the scheduler node.  The scheduler node reflects the
-     * priority of the thread within the corresponding scheduler instance.
-     */
-    union {
-      /**
-       * @brief A node for chains.
-       */
-      Chain_Node Chain;
-
-      /**
-       * @brief A node for red-black trees.
-       */
-      RBTree_Node RBTree;
-    } Node;
+    Priority_Aggregation Priority;
   } Wait;
 
   /**