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Commit adb92db8 authored by Ilpo Järvinen's avatar Ilpo Järvinen Committed by David S. Miller
Browse files

tcp: Make SACK code to split only at mss boundaries 



Sadly enough, this adds possible divide though we try to avoid
it by checking one mss as common case.

Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e8bae275

net/ipv4/tcp_input.c

+23 −4
Original line number Diff line number Diff line
@@ -1248,20 +1248,39 @@ static int tcp_match_skb_to_sack(struct sock *sk, struct sk_buff *skb, 
{

	int in_sack, err;

	unsigned int pkt_len;

	unsigned int mss;



	in_sack = !after(start_seq, TCP_SKB_CB(skb)->seq) &&

		  !before(end_seq, TCP_SKB_CB(skb)->end_seq);



	if (tcp_skb_pcount(skb) > 1 && !in_sack &&

	    after(TCP_SKB_CB(skb)->end_seq, start_seq)) {



		mss = tcp_skb_mss(skb);

		in_sack = !after(start_seq, TCP_SKB_CB(skb)->seq);



		if (!in_sack)

		if (!in_sack) {

			pkt_len = start_seq - TCP_SKB_CB(skb)->seq;

		else

			if (pkt_len < mss)

				pkt_len = mss;

		} else {

			pkt_len = end_seq - TCP_SKB_CB(skb)->seq;

		err = tcp_fragment(sk, skb, pkt_len, skb_shinfo(skb)->gso_size);

			if (pkt_len < mss)

				return -EINVAL;

		}



		/* Round if necessary so that SACKs cover only full MSSes

		 * and/or the remaining small portion (if present)

		 */

		if (pkt_len > mss) {

			unsigned int new_len = (pkt_len / mss) * mss;

			if (!in_sack && new_len < pkt_len) {

				new_len += mss;

				if (new_len > skb->len)

					return 0;

			}

			pkt_len = new_len;

		}

		err = tcp_fragment(sk, skb, pkt_len, mss);

		if (err < 0)

			return err;

	}