From: Bob Breuer <breuerr@mc.net>
Date: Fri, 2 Feb 2007 20:52:15 +0000 (-0800)
Subject: [PATCH] SPARC32: Fix over-optimization by GCC near ip_fast_csum.
X-Git-Tag: v2.6.19.3~12
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=594fb7bd8f3b317c531af7d00fb0967fb67e968d;p=thirdparty%2Fkernel%2Fstable.git

[PATCH] SPARC32: Fix over-optimization by GCC near ip_fast_csum.

In some cases such as:
	iph->check = 0;
	iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
GCC may optimize out the previous store.

Observed as a failure of NFS over udp (bad checksums on ip fragments)
when compiled with GCC 3.4.2.

Signed-off-by: Bob Breuer <breuerr@mc.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---

diff --git a/include/asm-sparc/checksum.h b/include/asm-sparc/checksum.h
index 286158108974b..acde719e00174 100644
--- a/include/asm-sparc/checksum.h
+++ b/include/asm-sparc/checksum.h
@@ -159,7 +159,7 @@ static inline unsigned short ip_fast_csum(const unsigned char *iph,
 			     "xnor\t%%g0, %0, %0"
 			     : "=r" (sum), "=&r" (iph)
 			     : "r" (ihl), "1" (iph)
-			     : "g2", "g3", "g4", "cc");
+			     : "g2", "g3", "g4", "cc", "memory");
 	return sum;
 }