--- a/hotspot/src/os_cpu/bsd_zero/vm/atomic_bsd_zero.inline.hpp	Tue Jan 06 19:30:28 2015 -0500
+++ b/hotspot/src/os_cpu/bsd_zero/vm/atomic_bsd_zero.inline.hpp	Wed Jan 07 16:43:04 2015 +0100
@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2003, 2014, Oracle and/or its affiliates. All rights reserved.
- * Copyright 2007, 2008, 2011 Red Hat, Inc.
+ * Copyright 2007, 2008, 2011, 2015, Red Hat, Inc.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -237,7 +237,13 @@
   // operation.  Note that some platforms only support this with the
   // limitation that the only valid value to store is the immediate
   // constant 1.  There is a test for this in JNI_CreateJavaVM().
-  return __sync_lock_test_and_set (dest, exchange_value);
+  jint result = __sync_lock_test_and_set (dest, exchange_value);
+  // All atomic operations are expected to be full memory barriers
+  // (see atomic.hpp). However, __sync_lock_test_and_set is not
+  // a full memory barrier, but an acquire barrier. Hence, this added
+  // barrier.
+  __sync_synchronize();
+  return result;
 #endif // M68K
 #endif // ARM
 }
@@ -250,7 +256,9 @@
 #ifdef M68K
   return m68k_lock_test_and_set(dest, exchange_value);
 #else
-  return __sync_lock_test_and_set (dest, exchange_value);
+  intptr_t result = __sync_lock_test_and_set (dest, exchange_value);
+  __sync_synchronize();
+  return result;
 #endif // M68K
 #endif // ARM
 }

--- a/hotspot/src/os_cpu/linux_zero/vm/atomic_linux_zero.inline.hpp	Tue Jan 06 19:30:28 2015 -0500
+++ b/hotspot/src/os_cpu/linux_zero/vm/atomic_linux_zero.inline.hpp	Wed Jan 07 16:43:04 2015 +0100
@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2003, 2014, Oracle and/or its affiliates. All rights reserved.
- * Copyright 2007, 2008, 2011 Red Hat, Inc.
+ * Copyright 2007, 2008, 2011, 2015, Red Hat, Inc.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -231,7 +231,13 @@
   // operation.  Note that some platforms only support this with the
   // limitation that the only valid value to store is the immediate
   // constant 1.  There is a test for this in JNI_CreateJavaVM().
-  return __sync_lock_test_and_set (dest, exchange_value);
+  jint result = __sync_lock_test_and_set (dest, exchange_value);
+  // All atomic operations are expected to be full memory barriers
+  // (see atomic.hpp). However, __sync_lock_test_and_set is not
+  // a full memory barrier, but an acquire barrier. Hence, this added
+  // barrier.
+  __sync_synchronize();
+  return result;
 #endif // M68K
 #endif // ARM
 }
@@ -244,7 +250,9 @@
 #ifdef M68K
   return m68k_lock_test_and_set(dest, exchange_value);
 #else
-  return __sync_lock_test_and_set (dest, exchange_value);
+  intptr_t result = __sync_lock_test_and_set (dest, exchange_value);
+  __sync_synchronize();
+  return result;
 #endif // M68K
 #endif // ARM
 }