X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=rts%2Fparallel%2FWSDeque.c;fp=rts%2Fparallel%2FWSDeque.c;h=f77ff0987db10702af3c2a56e70c3156fdebc48b;hb=a67183b75f1527edd88b071b879c2d07e8ac7653;hp=4ae9417fdbbb3ce012fa6a1b709136e8ff4382dc;hpb=2af2966da98c9c0da9e33c6aead9e1f86f94a362;p=ghc-hetmet.git

diff --git a/rts/parallel/WSDeque.c b/rts/parallel/WSDeque.c
index 4ae9417..f77ff09 100644
--- a/rts/parallel/WSDeque.c
+++ b/rts/parallel/WSDeque.c
@@ -186,8 +186,11 @@ stealWSDeque_ (WSDeque *q)
 // Can't do this on someone else's spark pool:
 // ASSERT_WSDEQUE_INVARIANTS(q); 
     
-    b = q->bottom;
+    // NB. these loads must be ordered, otherwise there is a race
+    // between steal and pop.
     t = q->top;
+    load_load_barrier();
+    b = q->bottom;
     
     // NB. b and t are unsigned; we need a signed value for the test
     // below, because it is possible that t > b during a