score: Fix SMP message handling

According to the C11 standard only atomic read-modify-write operations
guarantee that the last value written in modification order is read, see
"7.17.3 Order and consistency".  Thus we must use a read-modify-write in
_SMP_Inter_processor_interrupt_handler() to make sure we read an
up-to-date message.

1 files changed, 2 insertions, 14 deletions

diff --git a/cpukit/score/include/rtems/score/threadimpl.h b/cpukit/score/include/rtems/score/threadimpl.h
index 6bb78158e3..c878266c58 100644
--- a/cpukit/score/include/rtems/score/threadimpl.h
+++ b/cpukit/score/include/rtems/score/threadimpl.h
@@ -844,11 +844,7 @@ RTEMS_INLINE_ROUTINE void _Thread_Dispatch_update_heir(
 
   cpu_for_heir->heir = heir;
 
-  if ( cpu_for_heir == cpu_self ) {
-    cpu_self->dispatch_necessary = true;
-  } else {
-    _Per_CPU_Send_interrupt( cpu_for_heir );
-  }
+  _Thread_Dispatch_request( cpu_self, cpu_for_heir );
 }
 #endif
 
@@ -885,15 +881,7 @@ RTEMS_INLINE_ROUTINE void _Thread_Add_post_switch_action(
 
   action->handler = handler;
 
-#if defined(RTEMS_SMP)
-  if ( _Per_CPU_Get() == cpu_of_thread ) {
-    cpu_of_thread->dispatch_necessary = true;
-  } else {
-    _Per_CPU_Send_interrupt( cpu_of_thread );
-  }
-#else
-  cpu_of_thread->dispatch_necessary = true;
-#endif
+  _Thread_Dispatch_request( _Per_CPU_Get(), cpu_of_thread );
 
   _Chain_Append_if_is_off_chain_unprotected(
     &the_thread->Post_switch_actions.Chain,