Index: support.S
===================================================================
--- support.S	(revision 224216)
+++ support.S	(working copy)
@@ -404,6 +404,11 @@ fs_nofault_begin:
  * int32_t casuword32(volatile int32_t *p, int32_t e, int32_t s)
  */
 ENTRY(casuword32)
+	/*
+	 * XXX include a memory barrier in case this is used with release
+	 * semantics.
+	 */
+	membar	#LoadStore | #StoreStore
 	casa	[%o0] ASI_AIUP, %o1, %o2
 	retl
 	 mov	%o2, %o0
@@ -413,6 +418,11 @@ END(casuword32)
  * int64_t casuword64(volatile int64_t *p, int64_t e, int64_t s)
  */
 ENTRY(casuword64)
+	/*
+	 * XXX include a memory barrier in case this is used with release
+	 * semantics.
+	 */
+	membar	#LoadStore | #StoreStore
 	casxa	[%o0] ASI_AIUP, %o1, %o2
 	retl
 	 mov	%o2, %o0