ipv6: update skb->csum when CE mark is propagated

[pandora-kernel.git] / include / net / inet_ecn.h

diff --git a/include/net/inet_ecn.h b/include/net/inet_ecn.h
index 2fa1469..18f2d10 100644 (file)
--- a/include/net/inet_ecn.h
+++ b/include/net/inet_ecn.h
@@ -109,11 +109,24 @@ static inline void ipv4_copy_dscp(unsigned int dscp, struct iphdr *inner)
 
 struct ipv6hdr;
 
-static inline int IP6_ECN_set_ce(struct ipv6hdr *iph)
+/* Note:
+ * IP_ECN_set_ce() has to tweak IPV4 checksum when setting CE,
+ * meaning both changes have no effect on skb->csum if/when CHECKSUM_COMPLETE
+ * In IPv6 case, no checksum compensates the change in IPv6 header,
+ * so we have to update skb->csum.
+ */
+static inline int IP6_ECN_set_ce(struct sk_buff *skb, struct ipv6hdr *iph)
 {
+       __be32 from, to;
+
        if (INET_ECN_is_not_ect(ipv6_get_dsfield(iph)))
                return 0;
-       *(__be32*)iph |= htonl(INET_ECN_CE << 20);
+
+       from = *(__be32 *)iph;
+       to = from | htonl(INET_ECN_CE << 20);
+       *(__be32 *)iph = to;
+       if (skb->ip_summed == CHECKSUM_COMPLETE)
+               skb->csum = csum_add(csum_sub(skb->csum, from), to);
        return 1;
 }
 
@@ -138,7 +151,7 @@ static inline int INET_ECN_set_ce(struct sk_buff *skb)
 
        case cpu_to_be16(ETH_P_IPV6):
                if (skb->network_header + sizeof(struct ipv6hdr) <= skb->tail)
-                       return IP6_ECN_set_ce(ipv6_hdr(skb));
+                       return IP6_ECN_set_ce(skb, ipv6_hdr(skb));
                break;
        }