--- zzzz-none-000/linux-2.6.32.61/include/net/udp.h	2013-06-10 09:43:48.000000000 +0000
+++ ar10-7272-687/linux-2.6.32.61/include/net/udp.h	2017-01-26 13:51:06.000000000 +0000
@@ -111,6 +111,17 @@
 	return csum;
 }
 
+static inline __wsum udp_csum(struct sk_buff *skb)
+{
+	__wsum csum = csum_partial(skb_transport_header(skb),
+				   sizeof(struct udphdr), skb->csum);
+
+	for (skb = skb_shinfo(skb)->frag_list; skb; skb = skb->next) {
+		csum = csum_add(csum, skb->csum);
+	}
+	return csum;
+}
+
 /* hash routines shared between UDPv4/6 and UDP-Litev4/6 */
 static inline void udp_lib_hash(struct sock *sk)
 {