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, 7 insertions, 5 deletions

diff --git a/cpukit/score/src/threadqextractpriority.c b/cpukit/score/src/threadqextractpriority.c
index 724652ae8a..2f2555be33 100644
--- a/cpukit/score/src/threadqextractpriority.c
+++ b/cpukit/score/src/threadqextractpriority.c
@@ -24,8 +24,9 @@
 #include <rtems/score/threadimpl.h>
 #include <rtems/score/watchdogimpl.h>
 
-bool _Thread_queue_Extract_priority_helper(
+void _Thread_queue_Extract_priority_helper(
   Thread_Control       *the_thread,
+  uint32_t              return_code,
   bool                  requeuing
 )
 {
@@ -44,7 +45,7 @@ bool _Thread_queue_Extract_priority_helper(
   _ISR_Disable( level );
   if ( !_States_Is_waiting_on_thread_queue( the_thread->current_state ) ) {
     _ISR_Enable( level );
-    return false;
+    return;
   }
 
   /*
@@ -86,9 +87,12 @@ bool _Thread_queue_Extract_priority_helper(
 
   if ( requeuing ) {
     _ISR_Enable( level );
-    return true;
+    return;
   }
 
+  the_thread->Wait.queue = NULL;
+  the_thread->Wait.return_code = return_code;
+
   if ( !_Watchdog_Is_active( &the_thread->Timer ) ) {
     _ISR_Enable( level );
   } else {
@@ -102,6 +106,4 @@ bool _Thread_queue_Extract_priority_helper(
   if ( !_Objects_Is_local_id( the_thread->Object.id ) )
     _Thread_MP_Free_proxy( the_thread );
 #endif
-
-  return true;
 }