[NET]: ipvs checksum annotations.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ip_vs.h

@@ -990,12 +990,18 @@ extern void ip_vs_nat_icmp(struct sk_buff *skb, struct ip_vs_protocol *pp,
 
 extern __sum16 ip_vs_checksum_complete(struct sk_buff *skb, int offset);
 
-static inline u16 ip_vs_check_diff(u32 old, u32 new, u16 oldsum)
+static inline __wsum ip_vs_check_diff4(__be32 old, __be32 new, __wsum oldsum)
 {
-	u32 diff[2] = { old, new };
+	__be32 diff[2] = { ~old, new };
 
-	return csum_fold(csum_partial((char *) diff, sizeof(diff),
-				      oldsum ^ 0xFFFF));
+	return csum_partial((char *) diff, sizeof(diff), oldsum);
+}
+
+static inline __wsum ip_vs_check_diff2(__be16 old, __be16 new, __wsum oldsum)
+{
+	__be16 diff[2] = { ~old, new };
+
+	return csum_partial((char *) diff, sizeof(diff), oldsum);
 }
 
 #endif /* __KERNEL__ */

net/ipv4/ipvs/ip_vs_proto_tcp.c

@@ -116,9 +116,9 @@ tcp_fast_csum_update(struct tcphdr *tcph, __be32 oldip, __be32 newip,
 		     __be16 oldport, __be16 newport)
 {
 	tcph->check =
-		ip_vs_check_diff(~oldip, newip,
-				 ip_vs_check_diff(oldport ^ htons(0xFFFF),
-						  newport, tcph->check));
+		csum_fold(ip_vs_check_diff4(oldip, newip,
+				 ip_vs_check_diff2(oldport, newport,
+						~csum_unfold(tcph->check))));
 }
 
 

net/ipv4/ipvs/ip_vs_proto_udp.c

@@ -121,9 +121,9 @@ udp_fast_csum_update(struct udphdr *uhdr, __be32 oldip, __be32 newip,
 		     __be16 oldport, __be16 newport)
 {
 	uhdr->check =
-		ip_vs_check_diff(~oldip, newip,
-				 ip_vs_check_diff(oldport ^ htons(0xFFFF),
-						  newport, uhdr->check));
+		csum_fold(ip_vs_check_diff4(oldip, newip,
+				 ip_vs_check_diff2(oldport, newport,
+					~csum_unfold(uhdr->check))));
 	if (!uhdr->check)
 		uhdr->check = CSUM_MANGLED_0;
 }