csum_replace4
csum_replace4(ptr, from, to);
csum_replace4(sum, from, to);
csum_replace4(&iph->check, *oldip, newip);
csum_replace4(&iph->check, *oldip, *newip);
csum_replace4(&iph->check, addr, new_addr);
csum_replace4(&iph->check, addr, new_addr);
csum_replace4(&iph->check, iph->saddr, target->src.u3.ip);
csum_replace4(&iph->check, iph->daddr, target->dst.u3.ip);
csum_replace4(sum, (__force __be32)fsum, (__force __be32)tsum);
csum_replace4(&nh->check, *addr, new_addr);
csum_replace4(&iph->check, addr, new_addr);