Re: [PATCH mptcp-next v5 05/16] bpf: drop duplicate check_app_limited in tcp_bpf_push

[Geliang Tang <geliang@kernel.org>]

Hi Matt,

Thanks for the review.

On Sun, 2026-09-13 at 20:18 +0200, Matthieu Baerts wrote:
> Hi Geliang,
> 
> Thank you for sharing this!
> 
> On 13/09/2026 12:14, Geliang Tang wrote:
> > From: Geliang Tang <tanggeliang@kylinos.cn>
> > 
> > When the sendpage->MSG_SPLICE_PAGES migration series replaced
> > do_tcp_sendpages() with direct tcp_sendmsg_locked() calls, callers
> > that had used do_tcp_sendpages() kept an explicit
> > tcp_rate_check_app_limited(sk) that was originally needed to cover
> > do_tcp_sendpages() (which did not call tcp_rate_check_app_limited()
> > itself). After the inlining, tcp_sendmsg_locked() always provides
> > the check, and the outer call became redundant.
> > 
> > The site changed here, tcp_bpf_push(), is a MSG_SPLICE_PAGES loop
> > that holds the socket lock and only iterates when size > 0;
> > tcp_sendmsg_locked() is invoked on every iteration with state
> > identical to what the outer call sees, so dropping the outer call
> > is safe and behavior-preserving.
> If it is not related to MPTCP, could you please send this patch to
> netdev/bpf directly?
> 
> Also, should this be seen as a fix? From what I understand, some
> behaviours have changed, and it is only recently that this call is no
> longer needed.

I just sent this patch to netdev/bpf, along with another TLS one.

Thanks,
-Geliang

> 
> Cheers,
> Matt