xtensa: Fix checksum header file

We need to add a "memory" dependency (barrier) in assembly macros
that access (read or write) memory. Otherwise, the compiler might
ill-optimize the order of memory accesses.

Signed-off-by: Chris Zankel <chris@zankel.net>

1 files changed, 4 insertions, 2 deletions

diff --git a/arch/xtensa/include/asm/checksum.h b/arch/xtensa/include/asm/checksum.h
index f84d3f00774..e4d831a3077 100644
--- a/arch/xtensa/include/asm/checksum.h
+++ b/arch/xtensa/include/asm/checksum.h
@@ -113,7 +113,8 @@ static __inline__ __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
            are modified, we must also specify them as outputs, or gcc
            will assume they contain their original values. */
                 : "=r" (sum), "=r" (iph), "=r" (ihl), "=&r" (tmp), "=&r" (endaddr)
-                : "1" (iph), "2" (ihl));
+                : "1" (iph), "2" (ihl)
+                : "memory");
 
         return  csum_fold(sum);
 }
@@ -227,7 +228,8 @@ static __inline__ __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
                 "1:\t"
                 : "=r" (sum), "=&r" (__dummy)
                 : "r" (saddr), "r" (daddr),
-                  "r" (htonl(len)), "r" (htonl(proto)), "0" (sum));
+                  "r" (htonl(len)), "r" (htonl(proto)), "0" (sum)
+                : "memory");
 
         return csum_fold(sum);
 }