score: PR2172: _Thread_queue_Extract()

Add _Thread_queue_Extract_with_return_code().  On SMP this sequence in
_Thread_queue_Process_timeout() was broken:

[...]
      /*
       * After we enable interrupts here, a lot may happen in the
       * meantime, e.g. nested interrupts may release the resource that
       * times out here.  So we enter _Thread_queue_Extract()
       * speculatively.  Inside this function we check the actual status
       * under ISR disable protection.  This ensures that exactly one
       * executing context performs the extract operation (other parties
       * may call _Thread_queue_Dequeue()).  If this context won, then
       * we have a timeout.
       *
       * We can use the_thread_queue pointer here even if
       * the_thread->Wait.queue is already set to NULL since the extract
       * operation will only use the thread queue discipline to select
       * the right extract operation.  The timeout status is set during
       * thread queue initialization.
       */
      we_did_it = _Thread_queue_Extract( the_thread_queue, the_thread );
      if ( we_did_it ) {
        the_thread->Wait.return_code = the_thread_queue->timeout_status;
      }
[...]

In case _Thread_queue_Extract() successfully extracted a thread, then
this thread may start execution on a remote processor immediately and
read the the_thread->Wait.return_code before we update it here with the
timeout status.  Thus it observes a successful operation even if it
timed out.

1 files changed, 5 insertions, 1 deletions

diff --git a/cpukit/score/src/threadqrequeue.c b/cpukit/score/src/threadqrequeue.c
index 4eed7b3afe..ee15b3dec7 100644
--- a/cpukit/score/src/threadqrequeue.c
+++ b/cpukit/score/src/threadqrequeue.c
@@ -45,7 +45,11 @@ void _Thread_queue_Requeue(
     _ISR_Disable( level );
     if ( _States_Is_waiting_on_thread_queue( the_thread->current_state ) ) {
       _Thread_queue_Enter_critical_section( tq );
-      _Thread_queue_Extract_priority_helper( the_thread, true );
+      _Thread_queue_Extract_priority_helper(
+        the_thread,
+        the_thread->Wait.return_code,
+        true
+      );
       (void) _Thread_queue_Enqueue_priority( tq, the_thread, &level_ignored );
     }
     _ISR_Enable( level );