[RTEMS Project] #4679: Use priority inheritance for thread join

[RTEMS trac]

#4679: Use priority inheritance for thread join
------------------------------+-----------------------------
  Reporter:  Sebastian Huber  |      Owner:  Sebastian Huber
      Type:  enhancement      |     Status:  assigned
  Priority:  normal           |  Milestone:  6.1
 Component:  score            |    Version:  6
  Severity:  normal           |   Keywords:
Blocked By:                   |   Blocking:
------------------------------+-----------------------------
 Threads may join the thread termination of another thread using the
 `pthread_join()` or `rtems_task_delete()` directives. Currently, the
 thread join operation uses a special case priority boosting mechanism:
 {{{#!c
 static void _Thread_Raise_real_priority(
   Thread_Control   *the_thread,
   Priority_Control  priority
 )
 {
   Thread_queue_Context queue_context;

   _Thread_queue_Context_initialize( &queue_context );
   _Thread_queue_Context_clear_priority_updates( &queue_context );
   _Thread_Wait_acquire( the_thread, &queue_context );

   if ( priority < the_thread->Real_priority.priority ) {
     _Thread_Priority_change(
       the_thread,
       &the_thread->Real_priority,
       priority,
       PRIORITY_GROUP_LAST,
       &queue_context
     );
   }

   _Thread_Wait_release( the_thread, &queue_context );
   _Thread_Priority_update( &queue_context );
 }
 }}}
 The problem is that this approach is not transitive, it does not account
 for priority adjustments of the calling task while waiting for the join,
 clustered scheduling is not supported, and deadlocks are not detected. All
 these problems are fixed by using a priority inheritance thread queue for
 the join operation.

--
Ticket URL: <http://devel.rtems.org/ticket/4679>
RTEMS Project <http://www.rtems.org/>
RTEMS Project