score: Rework _Thread_Change_priority()

Move the writes to Thread_Control::current_priority and
Thread_Control::real_priority into _Thread_Change_priority() under the
protection of the thread lock.  Add a filter function to
_Thread_Change_priority() to enable specialized variants.

Avoid race conditions during a thread priority restore with the new
Thread_Control::priority_restore_hint for an important average case
optimizations used by priority inheritance mutexes.

Update #2273.

1 files changed, 32 insertions, 5 deletions

diff --git a/cpukit/score/src/threadsetpriority.c b/cpukit/score/src/threadsetpriority.c
index e1ff118c7e..f6a061a281 100644
--- a/cpukit/score/src/threadsetpriority.c
+++ b/cpukit/score/src/threadsetpriority.c
@@ -19,14 +19,41 @@
 #endif
 
 #include <rtems/score/threadimpl.h>
-#include <rtems/score/schedulerimpl.h>
 
-void _Thread_Set_priority(
+static bool _Thread_Set_priority_filter(
   Thread_Control   *the_thread,
-  Priority_Control  new_priority
+  Priority_Control *new_priority_ptr,
+  void             *arg
 )
 {
-  the_thread->current_priority = new_priority;
+  Priority_Control  current_priority;
+  Priority_Control  new_priority;
+  Priority_Control *old_priority_ptr;
+
+  current_priority = the_thread->current_priority;
+  new_priority = *new_priority_ptr;
+
+  old_priority_ptr = arg;
+  *old_priority_ptr = current_priority;
+
+  the_thread->real_priority = new_priority;
+
+  return _Thread_Priority_less_than( current_priority, new_priority )
+    || !_Thread_Owns_resources( the_thread );
+}
 
-  _Scheduler_Update_priority( the_thread, new_priority );
+void _Thread_Set_priority(
+  Thread_Control   *the_thread,
+  Priority_Control  new_priority,
+  Priority_Control *old_priority,
+  bool              prepend_it
+)
+{
+  _Thread_Change_priority(
+    the_thread,
+    new_priority,
+    old_priority,
+    _Thread_Set_priority_filter,
+    prepend_it
+  );
 }