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, 17 insertions, 4 deletions

diff --git a/cpukit/score/src/threadqextract.c b/cpukit/score/src/threadqextract.c
index 9563f44a1d..0a9c9d4932 100644
--- a/cpukit/score/src/threadqextract.c
+++ b/cpukit/score/src/threadqextract.c
@@ -21,9 +21,10 @@
 
 #include <rtems/score/threadqimpl.h>
 
-bool _Thread_queue_Extract(
+void _Thread_queue_Extract_with_return_code(
   Thread_queue_Control *the_thread_queue,
-  Thread_Control       *the_thread
+  Thread_Control       *the_thread,
+  uint32_t              return_code
 )
 {
   /*
@@ -31,8 +32,20 @@ bool _Thread_queue_Extract(
    * is a macro and the underlying methods do not have the same signature.
    */
   if  ( the_thread_queue->discipline == THREAD_QUEUE_DISCIPLINE_PRIORITY )
-    return _Thread_queue_Extract_priority( the_thread );
+    return _Thread_queue_Extract_priority( the_thread, return_code );
   else /* must be THREAD_QUEUE_DISCIPLINE_FIFO */
-    return _Thread_queue_Extract_fifo( the_thread );
+    return _Thread_queue_Extract_fifo( the_thread, return_code );
+
+}
 
+void _Thread_queue_Extract(
+  Thread_queue_Control *the_thread_queue,
+  Thread_Control       *the_thread
+)
+{
+  _Thread_queue_Extract_with_return_code(
+    the_thread_queue,
+    the_thread,
+    the_thread->Wait.return_code
+  );
 }