linux-kernel - Re: [PATCH RESEND net-next v2 1/5] tcp: fix stretch ACK bugs in BIC

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Date:   Mon, 16 Mar 2020 17:19:37 -0400
From:   Neal Cardwell <ncardwell@...gle.com>
To:     Pengcheng Yang <yangpc@...gsu.com>
Cc:     Eric Dumazet <edumazet@...gle.com>,
        David Miller <davem@...emloft.net>,
        Netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RESEND net-next v2 1/5] tcp: fix stretch ACK bugs in BIC

On Mon, Mar 16, 2020 at 2:36 AM Pengcheng Yang <yangpc@...gsu.com> wrote:
>
> Changes BIC to properly handle stretch ACKs in additive
> increase mode by passing in the count of ACKed packets
> to tcp_cong_avoid_ai().
>
> Signed-off-by: Pengcheng Yang <yangpc@...gsu.com>
> ---
>  net/ipv4/tcp_bic.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/net/ipv4/tcp_bic.c b/net/ipv4/tcp_bic.c
> index 645cc30..f5f588b 100644
> --- a/net/ipv4/tcp_bic.c
> +++ b/net/ipv4/tcp_bic.c
> @@ -145,12 +145,13 @@ static void bictcp_cong_avoid(struct sock *sk, u32 ack, u32 acked)
>         if (!tcp_is_cwnd_limited(sk))
>                 return;
>
> -       if (tcp_in_slow_start(tp))
> -               tcp_slow_start(tp, acked);
> -       else {
> -               bictcp_update(ca, tp->snd_cwnd);
> -               tcp_cong_avoid_ai(tp, ca->cnt, 1);
> +       if (tcp_in_slow_start(tp)) {
> +               acked = tcp_slow_start(tp, acked);
> +               if (!acked)
> +                       return;
>         }
> +       bictcp_update(ca, tp->snd_cwnd);
> +       tcp_cong_avoid_ai(tp, ca->cnt, acked);
>  }
>
>  /*
> --

Acked-by: Neal Cardwell <ncardwell@...gle.com>

thanks,
neal