Acked-by: Jon Maxwell <jmaxwel...@gmail.com>
Thanks for fixing that Eric.
On Fri, Sep 27, 2019 at 8:42 AM Eric Dumazet <eduma...@google.com> wrote:
>
> Yuchung Cheng and Marek Majkowski independently reported a weird
> behavior of TCP_USER_TIMEOUT option when used at connect() time.
>
> When the TCP_USER_TIMEOUT is reached, tcp_write_timeout()
> believes the flow should live, and the following condition
> in tcp_clamp_rto_to_user_timeout() programs one jiffie timers :
>
> remaining = icsk->icsk_user_timeout - elapsed;
> if (remaining <= 0)
> return 1; /* user timeout has passed; fire ASAP */
>
> This silly situation ends when the max syn rtx count is reached.
>
> This patch makes sure we honor both TCP_SYNCNT and TCP_USER_TIMEOUT,
> avoiding these spurious SYN packets.
>
> Fixes: b701a99e431d ("tcp: Add tcp_clamp_rto_to_user_timeout() helper to
> improve accuracy")
> Signed-off-by: Eric Dumazet <eduma...@google.com>
> Reported-by: Yuchung Cheng <ych...@google.com>
> Reported-by: Marek Majkowski <ma...@cloudflare.com>
> Cc: Jon Maxwell <jmaxwel...@gmail.com>
> Link: https://marc.info/?l=linux-netdev&m=156940118307949&w=2
> ---
> net/ipv4/tcp_timer.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
> index
> dbd9d2d0ee63aa46ad2dda417da6ec9409442b77..40de2d2364a1eca14c259d77ebed361d17829eb9
> 100644
> --- a/net/ipv4/tcp_timer.c
> +++ b/net/ipv4/tcp_timer.c
> @@ -210,7 +210,7 @@ static int tcp_write_timeout(struct sock *sk)
> struct inet_connection_sock *icsk = inet_csk(sk);
> struct tcp_sock *tp = tcp_sk(sk);
> struct net *net = sock_net(sk);
> - bool expired, do_reset;
> + bool expired = false, do_reset;
> int retry_until;
>
> if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
> @@ -242,9 +242,10 @@ static int tcp_write_timeout(struct sock *sk)
> if (tcp_out_of_resources(sk, do_reset))
> return 1;
> }
> + }
> + if (!expired)
> expired = retransmits_timed_out(sk, retry_until,
> icsk->icsk_user_timeout);
> - }
> tcp_fastopen_active_detect_blackhole(sk, expired);
>
> if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RTO_CB_FLAG))
> --
> 2.23.0.444.g18eeb5a265-goog
>
