ip_vs_checksum_complete
__sum16 ip_vs_checksum_complete(struct sk_buff *skb, int offset);
if (!skb_csum_unnecessary(skb) && ip_vs_checksum_complete(skb, ihl)) {
icmph->checksum = ip_vs_checksum_complete(skb, icmp_offset);
if (!skb_csum_unnecessary(skb) && ip_vs_checksum_complete(skb, ihl)) {