From adb92db857ee2a0a2b925ccfbd560203c3f88aae Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ilpo=20J=C3=A4rvinen?= Date: Mon, 24 Nov 2008 21:13:50 -0800 Subject: [PATCH] tcp: Make SACK code to split only at mss boundaries MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Sadly enough, this adds possible divide though we try to avoid it by checking one mss as common case. Signed-off-by: Ilpo Järvinen Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 27 +++++++++++++++++++++++---- 1 file changed, 23 insertions(+), 4 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 3f26599ddc88..ca46eb9151f8 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -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; } -- 2.39.2