linux-kernel - Re: [PATCH] tcp: Use REXMIT

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Date:   Fri, 17 Jan 2020 09:28:41 -0500
From:   Neal Cardwell <ncardwell@...gle.com>
To:     Pengcheng Yang <yangpc@...gsu.com>
Cc:     Eric Dumazet <edumazet@...gle.com>,
        David Miller <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] tcp: Use REXMIT_NEW instead of 2

On Fri, Jan 17, 2020 at 5:04 AM Pengcheng Yang <yangpc@...gsu.com> wrote:
>
> Use REXMIT_NEW instead of the confusing 2 in tcp_xmit_recovery()
>
> Signed-off-by: Pengcheng Yang <yangpc@...gsu.com>
> ---
>  net/ipv4/tcp_input.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
> index 5347ab2..de07439 100644
> --- a/net/ipv4/tcp_input.c
> +++ b/net/ipv4/tcp_input.c
> @@ -3554,7 +3554,7 @@ static void tcp_xmit_recovery(struct sock *sk, int rexmit)
>         if (rexmit == REXMIT_NONE || sk->sk_state == TCP_SYN_SENT)
>                 return;
>
> -       if (unlikely(rexmit == 2)) {
> +       if (unlikely(rexmit == REXMIT_NEW)) {
>                 __tcp_push_pending_frames(sk, tcp_current_mss(sk),
>                                           TCP_NAGLE_OFF);
>                 if (after(tp->snd_nxt, tp->high_seq))
> --

This change was already made recently in the net-next branch (see
below). To avoid duplicate work like this, please submit improvement
patches like this as patches against the very latest net-next branch
(or net branch, for bug fixes).

thanks,
neal

--

commit d0e8bcafc8aff5553beffe55046795f9bab9fe7b
Author: Mao Wenan <maowenan@...wei.com>
Date:   Thu Jan 2 22:02:27 2020 +0800

    tcp: use REXMIT_NEW instead of magic number

    REXMIT_NEW is a macro for "FRTO-style
    transmit of unsent/new packets", this patch
    makes it more readable.

    Signed-off-by: Mao Wenan <maowenan@...wei.com>
    Acked-by: Neal Cardwell <ncardwell@...gle.com>
    Signed-off-by: David S. Miller <davem@...emloft.net>

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 88b987ca9ebb..1d1e3493965f 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3550,7 +3550,7 @@ static void tcp_xmit_recovery(struct sock *sk, int rexmit)
        if (rexmit == REXMIT_NONE || sk->sk_state == TCP_SYN_SENT)
                return;

-       if (unlikely(rexmit == 2)) {
+       if (unlikely(rexmit == REXMIT_NEW)) {
                __tcp_push_pending_frames(sk, tcp_current_mss(sk),
                                          TCP_NAGLE_OFF);
                if (after(tp->snd_nxt, tp->high_seq))