csum_fold_helper
*csum = csum_fold_helper(*csum);
return csum_fold_helper(sum);
udph->check = (__u16)csum_fold_helper(udp_csum);
udph->check = (__u16)csum_fold_helper(udp_csum);
udph->check = (__u16)csum_fold_helper(udp_csum);
udph->check = (__u16)csum_fold_helper(udp_csum);