path: root/net/ipv4/tcp_timer.c
diff options
authorYuchung Cheng <ycheng@google.com>2013-10-29 10:09:05 -0700
committerDavid S. Miller <davem@davemloft.net>2013-10-29 22:50:41 -0400
commitc968601d174739cb1e7100c95e0eb3d2f7e91bc9 (patch)
treeba4605fa37ed4d0a8f47bd49c3cb53929285ebf3 /net/ipv4/tcp_timer.c
parentMerge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/jkirsher/net-next (diff)
tcp: temporarily disable Fast Open on SYN timeout
Fast Open currently has a fall back feature to address SYN-data being dropped but it requires the middle-box to pass on regular SYN retry after SYN-data. This is implemented in commit aab487435 ("net-tcp: Fast Open client - detecting SYN-data drops") However some NAT boxes will drop all subsequent packets after first SYN-data and blackholes the entire connections. An example is in commit 356d7d8 "netfilter: nf_conntrack: fix tcp_in_window for Fast Open". The sender should note such incidents and fall back to use the regular TCP handshake on subsequent attempts temporarily as well: after the second SYN timeouts the original Fast Open SYN is most likely lost. When such an event recurs Fast Open is disabled based on the number of recurrences exponentially. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to '')
1 files changed, 5 insertions, 1 deletions
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index af07b5b23ebf..64f0354c84c7 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -156,12 +156,16 @@ static bool retransmits_timed_out(struct sock *sk,
static int tcp_write_timeout(struct sock *sk)
struct inet_connection_sock *icsk = inet_csk(sk);
+ struct tcp_sock *tp = tcp_sk(sk);
int retry_until;
bool do_reset, syn_set = false;
if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
- if (icsk->icsk_retransmits)
+ if (icsk->icsk_retransmits) {
+ if (tp->syn_fastopen || tp->syn_data)
+ tcp_fastopen_cache_set(sk, 0, NULL, true);
+ }
retry_until = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
syn_set = true;
} else {