netdev - Re: mptcp splat

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Message-ID: <2ee8745cfa411fa2c397af8b1323f77e1bd00d29.camel@redhat.com>
Date: Fri, 29 Mar 2024 17:34:07 +0100
From: Paolo Abeni <pabeni@...hat.com>
To: Alexei Starovoitov <alexei.starovoitov@...il.com>, Matthieu Baerts
	 <matttbe@...nel.org>
Cc: Martin KaFai Lau <martin.lau@...ux.dev>, Network Development
 <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>, MPTCP Upstream
 <mptcp@...ts.linux.dev>, Mat Martineau <martineau@...nel.org>, Jakub
 Kicinski <kuba@...nel.org>, Martin KaFai Lau <martin.lau@...nel.org>,
 Geliang Tang <geliang@...nel.org>
Subject: Re: mptcp splat

On Fri, 2024-03-29 at 09:26 -0700, Alexei Starovoitov wrote:
> On Thu, Mar 28, 2024 at 10:35 AM Matthieu Baerts <matttbe@...nel.org> wrote:
> > 
> > Hi Martin,
> > 
> > On 27/03/2024 23:16, Martin KaFai Lau wrote:
> > 
> > (...)
> > 
> > > Unrelated, is there a way to tell if a tcp_sock is a subflow?
> > 
> > Yes, you can use "sk_is_mptcp(sk)". Please note that this 'sk' *has* to
> > be a tcp_sock, this is not checked by the helper.
> > 
> > That's what is used with bpf_mptcp_sock_from_subflow()
> > 
> > https://elixir.bootlin.com/linux/latest/source/net/mptcp/bpf.c#L15
> > 
> > > bpf prog
> > > can use it to decide if it wants to setsockopt on a subflow or not.
> > I think it is important to keep the possibility to set socket options
> > per subflow. If the original issue discussed here is limited to
> > set_rcvlowat(), best to address it there.
> 
> 
> All makes sense to me.
> 
> Paolo,
> could you send an official patch?

Sure, thank you for reminding me. This was falling off my radar. I'll
send it after some testing.

Thanks!

Paolo