1.0.41.6: threads: Insert barriers as appear to be required.

[sbcl.git] / contrib / sb-concurrency / queue.lisp

diff --git a/contrib/sb-concurrency/queue.lisp b/contrib/sb-concurrency/queue.lisp
index fec6d0f..a902785 100644 (file)
--- a/contrib/sb-concurrency/queue.lisp
+++ b/contrib/sb-concurrency/queue.lisp
@@ -66,6 +66,7 @@ and secondary value."
             (tail (queue-tail queue))
             (first-node-prev (node-prev head))
             (val (node-value head)))
+       (barrier (:read))
        (when (eq head (queue-head queue))
          (cond ((not (eq val +dummy+))
                 (if (eq tail head)