- skb = make_writable(skb, 0, gfp);
- if (skb) {
- struct iphdr *nh = ip_hdr(skb);
- u32 *f = a->type == ODPAT_SET_NW_SRC ? &nh->saddr : &nh->daddr;
- u32 old = *f;
- u32 new = a->nw_addr;
-
- if (key->nw_proto == IPPROTO_TCP) {
- struct tcphdr *th = tcp_hdr(skb);
- update_csum(&th->check, skb, old, new, 1);
- } else if (key->nw_proto == IPPROTO_UDP) {
- struct udphdr *th = udp_hdr(skb);
- update_csum(&th->check, skb, old, new, 1);
- }
- update_csum(&nh->check, skb, old, new, 0);
- *f = new;
+static __sum16 *get_l4_checksum(struct sk_buff *skb, const struct odp_flow_key *key)
+{
+ int transport_len = skb->len - skb_transport_offset(skb);
+ if (key->nw_proto == IPPROTO_TCP) {
+ if (likely(transport_len >= sizeof(struct tcphdr)))
+ return &tcp_hdr(skb)->check;
+ } else if (key->nw_proto == IPPROTO_UDP) {
+ if (likely(transport_len >= sizeof(struct udphdr)))
+ return &udp_hdr(skb)->check;