Re: [PATCH AUTOSEL 6.14 20/54] mptcp: move the whole rx path under msk socket lock protection

[Matthieu Baerts <matttbe@kernel.org>]

Hi Paolo,

(MPTCP list only)

On 03/04/2025 21:01, Sasha Levin wrote:
> From: Paolo Abeni <pabeni@redhat.com>
> 
> [ Upstream commit bc68b0efa1bf923cef1294a631d8e7416c7e06e4 ]
> 
> After commit c2e6048fa1cf ("mptcp: fix race in release_cb") we can
> move the whole MPTCP rx path under the socket lock leveraging the
> release_cb.
> 
> We can drop a bunch of spin_lock pairs in the receive functions, use
> a single receive queue and invoke __mptcp_move_skbs only when subflows
> ask for it.
> 
> This will allow more cleanup in the next patch.
> 
> Some changes are worth specific mention:
> 
> The msk rcvbuf update now always happens under both the msk and the
> subflow socket lock: we can drop a bunch of ONCE annotation and
> consolidate the checks.
> 
> When the skbs move is delayed at msk release callback time, even the
> msk rcvbuf update is delayed; additionally take care of such action in
> __mptcp_move_skbs().
> 
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> Reviewed-by: Mat Martineau <martineau@kernel.org>
> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
> Link: https://patch.msgid.link/20250218-net-next-mptcp-rx-path-refactor-v1-3-4a47d90d7998@kernel.org
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> Signed-off-by: Sasha Levin <sashal@kernel.org>

It is not clear to me why this patch has been selected by AUTOSEL for up
to 6.6, this is clearly not a fix. Do you think we should ask the stable
team to drop this patch?

Having this patch in stable might help for future backports, but I don't
know if it depends on others.

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.