diff options
| author | Enke Chen <enchen@paloaltonetworks.com> | 2021-01-15 14:30:58 -0800 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2021-01-18 19:59:17 -0800 |
| commit | 9d9b1ee0b2d1c9e02b2338c4a4b0a062d2d3edac (patch) | |
| tree | 2ea6293f10e4ca912540381678be42708f264e99 /net/ipv4/tcp_timer.c | |
| parent | b889c7c8c02ebb0b724e1b3998d7924122e49701 (diff) | |
tcp: fix TCP_USER_TIMEOUT with zero window
The TCP session does not terminate with TCP_USER_TIMEOUT when data
remain untransmitted due to zero window.
The number of unanswered zero-window probes (tcp_probes_out) is
reset to zero with incoming acks irrespective of the window size,
as described in tcp_probe_timer():
RFC 1122 4.2.2.17 requires the sender to stay open indefinitely
as long as the receiver continues to respond probes. We support
this by default and reset icsk_probes_out with incoming ACKs.
This counter, however, is the wrong one to be used in calculating the
duration that the window remains closed and data remain untransmitted.
Thanks to Jonathan Maxwell <jmaxwell37@gmail.com> for diagnosing the
actual issue.
In this patch a new timestamp is introduced for the socket in order to
track the elapsed time for the zero-window probes that have not been
answered with any non-zero window ack.
Fixes: 9721e709fa68 ("tcp: simplify window probe aborting on USER_TIMEOUT")
Reported-by: William McCall <william.mccall@gmail.com>
Co-developed-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Enke Chen <enchen@paloaltonetworks.com>
Reviewed-by: Yuchung Cheng <ycheng@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20210115223058.GA39267@localhost.localdomain
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/ipv4/tcp_timer.c')
| -rw-r--r-- | net/ipv4/tcp_timer.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index 6c62b9ea1320..454732ecc8f3 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -349,6 +349,7 @@ static void tcp_probe_timer(struct sock *sk) if (tp->packets_out || !skb) { icsk->icsk_probes_out = 0; + icsk->icsk_probes_tstamp = 0; return; } @@ -360,13 +361,12 @@ static void tcp_probe_timer(struct sock *sk) * corresponding system limit. We also implement similar policy when * we use RTO to probe window in tcp_retransmit_timer(). */ - if (icsk->icsk_user_timeout) { - u32 elapsed = tcp_model_timeout(sk, icsk->icsk_probes_out, - tcp_probe0_base(sk)); - - if (elapsed >= icsk->icsk_user_timeout) - goto abort; - } + if (!icsk->icsk_probes_tstamp) + icsk->icsk_probes_tstamp = tcp_jiffies32; + else if (icsk->icsk_user_timeout && + (s32)(tcp_jiffies32 - icsk->icsk_probes_tstamp) >= + msecs_to_jiffies(icsk->icsk_user_timeout)) + goto abort; max_probes = sock_net(sk)->ipv4.sysctl_tcp_retries2; if (sock_flag(sk, SOCK_DEAD)) { |