score: Fix blocking message queue receive

In order to ensure FIFO fairness across schedulers, the thread queue
surrender operation must be used to dequeue a thread from the thread
queue.  The thread queue extract operation is intended for timeouts.

Add _Thread_queue_Resume() which may be used to make extracted or
surrendered threads ready again.

Remove the now unused _Thread_queue_Extract_critical() function.

Close #4509.

1 files changed, 12 insertions, 8 deletions

diff --git a/cpukit/score/src/coremsgseize.c b/cpukit/score/src/coremsgseize.c
index e44538ee17..148e9dbb3c 100644
--- a/cpukit/score/src/coremsgseize.c
+++ b/cpukit/score/src/coremsgseize.c
@@ -56,7 +56,8 @@ Status_Control _CORE_message_queue_Seize(
       return STATUS_SUCCESSFUL;
     #else
     {
-      Thread_Control   *the_thread;
+      Thread_queue_Heads *heads;
+      Thread_Control     *the_thread;
 
       /*
        *  There could be a thread waiting to send a message.  If there
@@ -65,11 +66,8 @@ Status_Control _CORE_message_queue_Seize(
        *  NOTE: If we note that the queue was not full before this receive,
        *  then we can avoid this dequeue.
        */
-      the_thread = _Thread_queue_First_locked(
-        &the_message_queue->Wait_queue,
-        the_message_queue->operations
-      );
-      if ( the_thread == NULL ) {
+      heads = the_message_queue->Wait_queue.Queue.heads;
+      if ( heads == NULL ) {
         _CORE_message_queue_Free_message_buffer(
           the_message_queue,
           the_message
@@ -78,6 +76,13 @@ Status_Control _CORE_message_queue_Seize(
         return STATUS_SUCCESSFUL;
       }
 
+      the_thread = ( *the_message_queue->operations->surrender )(
+        &the_message_queue->Wait_queue.Queue,
+        heads,
+        NULL,
+        queue_context
+      );
+
       /*
        *  There was a thread waiting to send a message.  This code
        *  puts the messages in the message queue on behalf of the
@@ -90,9 +95,8 @@ Status_Control _CORE_message_queue_Seize(
         (size_t) the_thread->Wait.option,
         (CORE_message_queue_Submit_types) the_thread->Wait.count
       );
-      _Thread_queue_Extract_critical(
+      _Thread_queue_Resume(
         &the_message_queue->Wait_queue.Queue,
-        the_message_queue->operations,
         the_thread,
         queue_context
       );