Commit c17a8003 authored by Herbert Xu's avatar Herbert Xu Committed by Luis Henriques

tcp: Do not apply TSO segment limit to non-TSO packets

commit 843925f3 upstream.

Thomas Jarosch reported IPsec TCP stalls when a PMTU event occurs.

In fact the problem was completely unrelated to IPsec.  The bug is
also reproducible if you just disable TSO/GSO.

The problem is that when the MSS goes down, existing queued packet
on the TX queue that have not been transmitted yet all look like
TSO packets and get treated as such.

This then triggers a bug where tcp_mss_split_point tells us to
generate a zero-sized packet on the TX queue.  Once that happens
we're screwed because the zero-sized packet can never be removed
by ACKs.

Fixes: 1485348d ("tcp: Apply device TSO segment limit earlier")
Reported-by: default avatarThomas Jarosch <thomas.jarosch@intra2net.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>

Cheers,
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
[ luis: backported to 3.16: used davem's backport to 3.18 ]
Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
parent b2108a88
......@@ -1935,7 +1935,7 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now)))
break;
if (tso_segs == 1) {
if (tso_segs == 1 || !sk->sk_gso_max_segs) {
if (unlikely(!tcp_nagle_test(tp, skb, mss_now,
(tcp_skb_is_last(sk, skb) ?
nonagle : TCP_NAGLE_PUSH))))
......@@ -1971,7 +1971,7 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
}
limit = mss_now;
if (tso_segs > 1 && !tcp_urg_mode(tp))
if (tso_segs > 1 && sk->sk_gso_max_segs && !tcp_urg_mode(tp))
limit = tcp_mss_split_point(sk, skb, mss_now,
min_t(unsigned int,
cwnd_quota,
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment