--- tsan_interface_atomic.cc.jj	2012-11-23 17:20:49.000000000 +0100
+++ tsan_interface_atomic.cc	2012-11-23 19:06:05.917147568 +0100
@@ -199,15 +199,17 @@ static T AtomicFetchXor(ThreadState *thr
 template<typename T>
 static bool AtomicCAS(ThreadState *thr, uptr pc,
     volatile T *a, T *c, T v, morder mo, morder fmo) {
-  (void)fmo;
   if (IsReleaseOrder(mo))
     Release(thr, pc, (uptr)a);
   T cc = *c;
   T pr = __sync_val_compare_and_swap(a, cc, v);
-  if (IsAcquireOrder(mo))
-    Acquire(thr, pc, (uptr)a);
-  if (pr == cc)
+  if (pr == cc) {
+    if (IsAcquireOrder(mo))
+      Acquire(thr, pc, (uptr)a);
     return true;
+  }
+  if (IsAcquireOrder(fmo))
+    Acquire(thr, pc, (uptr)a);
   *c = pr;
   return false;
 }