+struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int features)
+{
+ struct sk_buff *segs = ERR_PTR(-EINVAL);
+ struct tcphdr *th;
+ unsigned thlen;
+ unsigned int seq;
+ unsigned int delta;
+ unsigned int oldlen;
+ unsigned int len;
+
+ if (!pskb_may_pull(skb, sizeof(*th)))
+ goto out;
+
+ th = skb->h.th;
+ thlen = th->doff * 4;
+ if (thlen < sizeof(*th))
+ goto out;
+
+ if (!pskb_may_pull(skb, thlen))
+ goto out;
+
+ oldlen = (u16)~skb->len;
+ __skb_pull(skb, thlen);
+
+ if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
+ /* Packet is from an untrusted source, reset gso_segs. */
+ int type = skb_shinfo(skb)->gso_type;
+ int mss;
+
+ if (unlikely(type &
+ ~(SKB_GSO_TCPV4 |
+ SKB_GSO_DODGY |
+ SKB_GSO_TCP_ECN |
+ SKB_GSO_TCPV6 |
+ 0) ||
+ !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))))
+ goto out;
+
+ mss = skb_shinfo(skb)->gso_size;
+ skb_shinfo(skb)->gso_segs = (skb->len + mss - 1) / mss;
+
+ segs = NULL;
+ goto out;
+ }
+
+ segs = skb_segment(skb, features);
+ if (IS_ERR(segs))
+ goto out;
+
+ len = skb_shinfo(skb)->gso_size;
+ delta = htonl(oldlen + (thlen + len));
+
+ skb = segs;
+ th = skb->h.th;
+ seq = ntohl(th->seq);
+
+ do {
+ th->fin = th->psh = 0;
+
+ th->check = ~csum_fold(th->check + delta);
+ if (skb->ip_summed != CHECKSUM_HW)
+ th->check = csum_fold(csum_partial(skb->h.raw, thlen,
+ skb->csum));
+
+ seq += len;
+ skb = skb->next;
+ th = skb->h.th;
+
+ th->seq = htonl(seq);
+ th->cwr = 0;
+ } while (skb->next);
+
+ delta = htonl(oldlen + (skb->tail - skb->h.raw) + skb->data_len);
+ th->check = ~csum_fold(th->check + delta);
+ if (skb->ip_summed != CHECKSUM_HW)
+ th->check = csum_fold(csum_partial(skb->h.raw, thlen,
+ skb->csum));
+
+out:
+ return segs;
+}
+EXPORT_SYMBOL(tcp_tso_segment);
+