x86: fix csum_ipv6_magic asm memory clobber

Just like ip_fast_csum, the assembly snippet in csum_ipv6_magic needs a
memory clobber, as it is only passed the address of the buffer, not a
memory reference to the buffer itself.

This caused failures in Hurd's pfinetv4 when we tried to compile it with
gcc-4.3 (bogus checksums).

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Acked-by: "David S. Miller" <davem@davemloft.net>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/arch/x86/include/asm/checksum_32.h b/arch/x86/include/asm/checksum_32.h
index 7c5ef8b14d92..46fc474fd819 100644
--- a/arch/x86/include/asm/checksum_32.h
+++ b/arch/x86/include/asm/checksum_32.h
@@ -161,7 +161,8 @@ static inline __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
             "adcl $0, %0        ;\n"
             : "=&r" (sum)
             : "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);
 }