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, 6 deletions

diff --git a/cpukit/score/src/threadqprocesstimeout.c b/cpukit/score/src/threadqprocesstimeout.c
index feb09210e5..616901900d 100644
--- a/cpukit/score/src/threadqprocesstimeout.c
+++ b/cpukit/score/src/threadqprocesstimeout.c
@@ -51,8 +51,6 @@ void _Thread_queue_Process_timeout(
       }
       _ISR_Enable( level );
     } else {
-      bool we_did_it;
-
       _ISR_Enable( level );
 
       /*
@@ -70,10 +68,11 @@ void _Thread_queue_Process_timeout(
        * 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;
-      }
+      _Thread_queue_Extract_with_return_code(
+        the_thread_queue,
+        the_thread,
+        the_thread_queue->timeout_status
+      );
     }
   } else {
     _ISR_Enable( level );