checksum_fold
return checksum_fold(buf, sizeof(struct tcphdr) + payload_len, sum);
iph->check = checksum_fold(buf, sizeof(struct iphdr), 0);
iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
iph->check = checksum_fold(iph, sizeof(struct iphdr) + optlen, 0);
iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
return ~checksum_fold(NULL, 0, sum);
return checksum_fold(th, len, sum);
iph->check = checksum_fold(iph, sizeof(*iph), 0);