linux-kernel - Re: [PATCH] net: remove release/lock_sock in tcp_splice

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Message-ID: <CAL+tcoAiOwWEsbkqSJ3kpwLxd8seBBUOAODeBideFdQYV7LfWg@mail.gmail.com>
Date: Thu, 15 Aug 2024 18:55:13 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: Paolo Abeni <pabeni@...hat.com>
Cc: sunyiqi <sunyiqixm@...il.com>, edumazet@...gle.com, davem@...emloft.net, 
	dsahern@...nel.org, kuba@...nel.org, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: remove release/lock_sock in tcp_splice_read

Hello Paolo,

On Thu, Aug 15, 2024 at 6:40 PM Paolo Abeni <pabeni@...hat.com> wrote:
[...]
> > -             release_sock(sk);
> > -             lock_sock(sk);
>
> This is needed to flush the sk backlog.
>
> Somewhat related, I think we could replace the pair with sk_flush_backlog().
>

Do you think we could do this like the following commit:

commit d41a69f1d390fa3f2546498103cdcd78b30676ff
Author: Eric Dumazet <edumazet@...gle.com>
Date:   Fri Apr 29 14:16:53 2016 -0700

    tcp: make tcp_sendmsg() aware of socket backlog

    Large sendmsg()/write() hold socket lock for the duration of the call,
    unless sk->sk_sndbuf limit is hit. This is bad because incoming packets
    are parked into socket backlog for a long time.

?

Then we can avoid taking the lock too long which results in too many
packets in the backlog.

Thanks,
Jason