lkml.org 
[lkml]   [2020]   [Jan]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 2/3] tcp: Reduce SYN resend delay if a suspicous ACK is received
On Fri, Jan 31, 2020 at 4:25 AM <sjpark@amazon.com> wrote:

> Signed-off-by: SeongJae Park <sjpark@amazon.de>
> ---
> net/ipv4/tcp_input.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
> index 2a976f57f7e7..b168e29e1ad1 100644
> --- a/net/ipv4/tcp_input.c
> +++ b/net/ipv4/tcp_input.c
> @@ -5893,8 +5893,12 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
> * the segment and return)"
> */
> if (!after(TCP_SKB_CB(skb)->ack_seq, tp->snd_una) ||
> - after(TCP_SKB_CB(skb)->ack_seq, tp->snd_nxt))
> + after(TCP_SKB_CB(skb)->ack_seq, tp->snd_nxt)) {
> + /* Previous FIN/ACK or RST/ACK might be ignore. */
> + inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
> + TCP_ATO_MIN, TCP_RTO_MAX);

This is not what I suggested.

I suggested implementing a strategy where only the _first_ retransmit
would be done earlier.

So you need to look at the current counter of retransmit attempts,
then reset the timer if this SYN_SENT
socket never resent a SYN.

We do not want to trigger packet storms, if for some reason the remote
peer constantly sends
us the same packet.

Thanks.

> goto reset_and_undo;
> + }
>
> if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr &&
> !between(tp->rx_opt.rcv_tsecr, tp->retrans_stamp,
> --
> 2.17.1
>

\
 
 \ /
  Last update: 2020-01-31 16:02    [W:0.072 / U:0.256 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site