s390/cmpxchg: add missing memory barrier to cmpxchg64

All cmpxchg functions imply a memory barrier.
cmpxch64 did not have one for 31 bit code, so add it.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/s390/include/asm/cmpxchg.h b/arch/s390/include/asm/cmpxchg.h
index 81d7908416cf..ebd31481f1d2 100644
--- a/arch/s390/include/asm/cmpxchg.h
+++ b/arch/s390/include/asm/cmpxchg.h
@@ -181,7 +181,7 @@ static inline unsigned long long __cmpxchg64(void *ptr,
                 "       cds     %0,%2,%1"
                 : "+&d" (rp_old), "=Q" (ptr)
                 : "d" (rp_new), "Q" (ptr)
-                : "cc");
+                : "memory", "cc");
         return rp_old.pair;
 }
 #define cmpxchg64(ptr, o, n)                                            \