- if (ip_conntrack_checksum && hooknum == NF_IP_PRE_ROUTING &&
- nf_ip_checksum(skb, hooknum, iph->ihl * 4, IPPROTO_UDP)) {
+ if (hooknum == NF_IP_PRE_ROUTING
+ && skb->ip_summed != CHECKSUM_UNNECESSARY
+ && csum_tcpudp_magic(iph->saddr, iph->daddr, udplen, IPPROTO_UDP,
+ skb->ip_summed == CHECKSUM_HW ? skb->csum
+ : skb_checksum(skb, iph->ihl*4, udplen, 0))) {