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tcp: Make SACK code to split only at mss boundaries

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

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ilpo Järvinen 2008-11-24 21:13:50 -08:00 • committed by David S. Miller
commit adb92db857
1 changed files with 23 additions and 4 deletions
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27
net/ipv4/tcp_input.c
View file

@ -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;
}