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, 44 insertions, 59 deletions

diff --git a/cpukit/posix/src/pthread.c b/cpukit/posix/src/pthread.c
index a1394a5dee..9cd730b59f 100644
--- a/cpukit/posix/src/pthread.c
+++ b/cpukit/posix/src/pthread.c
@@ -82,85 +82,70 @@ pthread_attr_t _POSIX_Threads_Default_attributes = {
   #endif
 };
 
-static bool _POSIX_Threads_Sporadic_timer_filter(
-  Thread_Control   *the_thread,
-  Priority_Control *new_priority_p,
-  void             *arg
-)
+void _POSIX_Threads_Sporadic_timer( Watchdog_Control *watchdog )
 {
-  POSIX_API_Control *api;
-  Priority_Control   current_priority;
-  Priority_Control   new_priority;
+  POSIX_API_Control    *api;
+  Thread_Control       *the_thread;
+  Thread_queue_Context  queue_context;
 
-  api = arg;
-
-  new_priority = api->Sporadic.high_priority;
-  *new_priority_p = new_priority;
+  api = RTEMS_CONTAINER_OF( watchdog, POSIX_API_Control, Sporadic.Timer );
+  the_thread = api->thread;
 
-  current_priority = _Thread_Get_priority( the_thread );
-  the_thread->real_priority = new_priority;
+  _Thread_queue_Context_clear_priority_updates( &queue_context );
+  _Thread_Wait_acquire( the_thread, &queue_context );
+
+  if ( _Priority_Node_is_active( &api->Sporadic.Low_priority ) ) {
+    _Thread_Priority_add(
+      the_thread,
+      &the_thread->Real_priority,
+      &queue_context
+    );
+    _Thread_Priority_remove(
+      the_thread,
+      &api->Sporadic.Low_priority,
+      &queue_context
+    );
+    _Priority_Node_set_inactive( &api->Sporadic.Low_priority );
+  }
 
   _Watchdog_Per_CPU_remove_relative( &api->Sporadic.Timer );
   _POSIX_Threads_Sporadic_timer_insert( the_thread, api );
 
-  return _Thread_Priority_less_than( current_priority, new_priority )
-    || !_Thread_Owns_resources( the_thread );
-}
-
-static void _POSIX_Threads_Sporadic_timer( Watchdog_Control *watchdog )
-{
-  POSIX_API_Control *api;
-  Thread_Control    *the_thread;
-
-  api = RTEMS_CONTAINER_OF( watchdog, POSIX_API_Control, Sporadic.Timer );
-  the_thread = api->thread;
-
-  _Thread_Change_priority(
-    the_thread,
-    0,
-    api,
-    _POSIX_Threads_Sporadic_timer_filter,
-    true
-  );
+  _Thread_Wait_release( the_thread, &queue_context );
+  _Thread_Priority_update( &queue_context );
 }
 
-static bool _POSIX_Threads_Sporadic_budget_callout_filter(
-  Thread_Control   *the_thread,
-  Priority_Control *new_priority_p,
-  void             *arg
-)
+void _POSIX_Threads_Sporadic_budget_callout( Thread_Control *the_thread )
 {
-  POSIX_API_Control *api;
-  Priority_Control   current_priority;
-  Priority_Control   new_priority;
+  POSIX_API_Control    *api;
+  Thread_queue_Context  queue_context;
 
   api = the_thread->API_Extensions[ THREAD_API_POSIX ];
 
+  _Thread_queue_Context_clear_priority_updates( &queue_context );
+  _Thread_Wait_acquire( the_thread, &queue_context );
+
   /*
    *  This will prevent the thread from consuming its entire "budget"
    *  while at low priority.
    */
   the_thread->cpu_time_budget = UINT32_MAX;
 
-  new_priority = api->Sporadic.low_priority;
-  *new_priority_p = new_priority;
-
-  current_priority = _Thread_Get_priority( the_thread );
-  the_thread->real_priority = new_priority;
-
-  return _Thread_Priority_less_than( current_priority, new_priority )
-    || !_Thread_Owns_resources( the_thread );
-}
+  if ( !_Priority_Node_is_active( &api->Sporadic.Low_priority ) ) {
+    _Thread_Priority_add(
+      the_thread,
+      &api->Sporadic.Low_priority,
+      &queue_context
+    );
+    _Thread_Priority_remove(
+      the_thread,
+      &the_thread->Real_priority,
+      &queue_context
+    );
+  }
 
-void _POSIX_Threads_Sporadic_budget_callout( Thread_Control *the_thread )
-{
-  _Thread_Change_priority(
-    the_thread,
-    0,
-    NULL,
-    _POSIX_Threads_Sporadic_budget_callout_filter,
-    true
-  );
+  _Thread_Wait_release( the_thread, &queue_context );
+  _Thread_Priority_update( &queue_context );
 }
 
 /*