netdev - Re: [PATCH net-next 01/11] tcp: add tcp_rcvbuf

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Message-ID: <CANn89iK3n=iCQ5z3ScMvSR5_J=oxaXhrS=JF2fzALuAfeZHoEA@mail.gmail.com>
Date: Wed, 14 May 2025 08:38:36 -0700
From: Eric Dumazet <edumazet@...gle.com>
To: David Ahern <dsahern@...nel.org>
Cc: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, Neal Cardwell <ncardwell@...gle.com>, 
	Simon Horman <horms@...nel.org>, Kuniyuki Iwashima <kuniyu@...zon.com>, Rick Jones <jonesrick@...gle.com>, 
	Wei Wang <weiwan@...gle.com>, netdev@...r.kernel.org, eric.dumazet@...il.com
Subject: Re: [PATCH net-next 01/11] tcp: add tcp_rcvbuf_grow() tracepoint

On Wed, May 14, 2025 at 8:30 AM David Ahern <dsahern@...nel.org> wrote:
>
> On 5/13/25 1:39 PM, Eric Dumazet wrote:
> > diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
> > index a35018e2d0ba27b14d0b59d3728f7181b1a51161..88beb6d0f7b5981e65937a6727a1111fd341335b 100644
> > --- a/net/ipv4/tcp_input.c
> > +++ b/net/ipv4/tcp_input.c
> > @@ -769,6 +769,8 @@ void tcp_rcv_space_adjust(struct sock *sk)
> >       if (copied <= tp->rcvq_space.space)
> >               goto new_measure;
> >
> > +     trace_tcp_rcvbuf_grow(sk, time);
>
> tracepoints typically take on the name of the function. Patch 2 moves a
> lot of logic from tcp_rcv_space_adjust to tcp_rcvbuf_grow but does not
> move this tracepoint into it. For sake of consistency, why not do that -
> and add this patch after the code move?

Prior value is needed in the tracepoint, but in patch 2, I call
tcp_rcvbuf_grow() after it is overwritten.

I was planning to add a call to this tracepoint from
tcp_data_queue_ofo(), with 'time==0', in the third patch.

But I found this quite noisy and not useful, so I removed it from the OFO case.