score: Fix CPU time used by executing threads

The CPU time used of a thread was previously maintained per-processor
mostly during _Thread_Dispatch().  However, on SMP configurations the
actual processor of a thread is difficult to figure out since thread
dispatching is a highly asynchronous process (e.g. via inter-processor
interrupts).  Only the intended processor of a thread is known to the
scheduler easily.  Do the CPU usage accounting during thread heir
updates in the context of the scheduler operations.  Provide the
function _Thread_Get_CPU_time_used() to get the CPU usage of a thread
using proper locks to get a consistent value.

Close #2627.

1 files changed, 19 insertions, 13 deletions

diff --git a/cpukit/score/include/rtems/score/schedulerimpl.h b/cpukit/score/include/rtems/score/schedulerimpl.h
index d50c36a7b9..a41b7ea62f 100644
--- a/cpukit/score/include/rtems/score/schedulerimpl.h
+++ b/cpukit/score/include/rtems/score/schedulerimpl.h
@@ -627,19 +627,6 @@ bool _Scheduler_Set_affinity(
 
 #endif /* defined(__RTEMS_HAVE_SYS_CPUSET_H__) */
 
-RTEMS_INLINE_ROUTINE void _Scheduler_Update_heir(
-  Thread_Control *new_heir,
-  bool            force_dispatch
-)
-{
-  Thread_Control *heir = _Thread_Heir;
-
-  if ( heir != new_heir && ( heir->is_preemptible || force_dispatch ) ) {
-    _Thread_Heir = new_heir;
-    _Thread_Dispatch_necessary = true;
-  }
-}
-
 RTEMS_INLINE_ROUTINE void _Scheduler_Generic_block(
   const Scheduler_Control *scheduler,
   Thread_Control          *the_thread,
@@ -1356,6 +1343,25 @@ RTEMS_INLINE_ROUTINE bool _Scheduler_Ask_blocked_node_for_help(
 
 ISR_LOCK_DECLARE( extern, _Scheduler_Lock )
 
+RTEMS_INLINE_ROUTINE void _Scheduler_Update_heir(
+  Thread_Control *new_heir,
+  bool            force_dispatch
+)
+{
+  Thread_Control *heir = _Thread_Heir;
+
+  if ( heir != new_heir && ( heir->is_preemptible || force_dispatch ) ) {
+#if defined(RTEMS_SMP)
+    /* We need this state only for _Thread_Get_CPU_time_used() */
+    _Scheduler_Thread_change_state( heir, THREAD_SCHEDULER_BLOCKED );
+    _Scheduler_Thread_change_state( new_heir, THREAD_SCHEDULER_SCHEDULED );
+#endif
+    _Thread_Update_CPU_time_used( heir, _Thread_Get_CPU( heir ) );
+    _Thread_Heir = new_heir;
+    _Thread_Dispatch_necessary = true;
+  }
+}
+
 /**
  * @brief Acquires the scheduler instance of the thread.
  *