diff options
| author | Yuchung Cheng <ycheng@google.com> | 2015-11-18 18:17:30 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-11-20 10:51:12 -0500 |
| commit | 0e45f4da5981895e885dd72fe912a3f8e32bae73 (patch) | |
| tree | f3396ee4df16edd93595e8fc878cfad1421b67bb /net/ipv4/tcp_timer.c | |
| parent | 0db19b850468a24b70d8471f5ebe71f0a035bbab (diff) | |
| download | lwn-0e45f4da5981895e885dd72fe912a3f8e32bae73.tar.gz lwn-0e45f4da5981895e885dd72fe912a3f8e32bae73.zip | |
tcp: disable Fast Open on timeouts after handshake
Some middle-boxes black-hole the data after the Fast Open handshake
(https://www.ietf.org/proceedings/94/slides/slides-94-tcpm-13.pdf).
The exact reason is unknown. The work-around is to disable Fast Open
temporarily after multiple recurring timeouts with few or no data
delivered in the established state.
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Christoph Paasch <cpaasch@apple.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_timer.c')
| -rw-r--r-- | net/ipv4/tcp_timer.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index c9c716a483e4..448603a81966 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -176,6 +176,18 @@ static int tcp_write_timeout(struct sock *sk) syn_set = true; } else { if (retransmits_timed_out(sk, sysctl_tcp_retries1, 0, 0)) { + /* Some middle-boxes may black-hole Fast Open _after_ + * the handshake. Therefore we conservatively disable + * Fast Open on this path on recurring timeouts with + * few or zero bytes acked after Fast Open. + */ + if (tp->syn_data_acked && + tp->bytes_acked <= tp->rx_opt.mss_clamp) { + tcp_fastopen_cache_set(sk, 0, NULL, true, 0); + if (icsk->icsk_retransmits == sysctl_tcp_retries1) + NET_INC_STATS_BH(sock_net(sk), + LINUX_MIB_TCPFASTOPENACTIVEFAIL); + } /* Black hole detection */ tcp_mtu_probing(icsk, sk); |