diff --git a/include/net/udp.h b/include/net/udp.h
index e82f3a8..67ea6fc 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -144,6 +144,17 @@
 	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)
 {