Re: FAILED: patch "[PATCH] mptcp: pm: only mark 'subflow' endp as available" failed to apply to 5.15-stable tree

[Matthieu Baerts <matttbe@kernel.org>]

Hi Greg,

On 26/08/2024 14:06, gregkh@linuxfoundation.org wrote:
> 
> The patch below does not apply to the 5.15-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.

Thank you for the notification!

(...)

> ------------------ original commit in Linus's tree ------------------
> 
> From 322ea3778965da72862cca2a0c50253aacf65fe6 Mon Sep 17 00:00:00 2001
> From: "Matthieu Baerts (NGI0)" <matttbe@kernel.org>
> Date: Mon, 19 Aug 2024 21:45:26 +0200
> Subject: [PATCH] mptcp: pm: only mark 'subflow' endp as available
> 
> Adding the following warning ...
> 
>   WARN_ON_ONCE(msk->pm.local_addr_used == 0)
> 
> ... before decrementing the local_addr_used counter helped to find a bug
> when running the "remove single address" subtest from the mptcp_join.sh
> selftests.
> 
> Removing a 'signal' endpoint will trigger the removal of all subflows
> linked to this endpoint via mptcp_pm_nl_rm_addr_or_subflow() with
> rm_type == MPTCP_MIB_RMSUBFLOW. This will decrement the local_addr_used
> counter, which is wrong in this case because this counter is linked to
> 'subflow' endpoints, and here it is a 'signal' endpoint that is being
> removed.
> 
> Now, the counter is decremented, only if the ID is being used outside
> of mptcp_pm_nl_rm_addr_or_subflow(), only for 'subflow' endpoints, and
> if the ID is not 0 -- local_addr_used is not taking into account these
> ones. This marking of the ID as being available, and the decrement is
> done no matter if a subflow using this ID is currently available,
> because the subflow could have been closed before.
> 
> Fixes: 06faa2271034 ("mptcp: remove multi addresses and subflows in PM")

Similar to my previous message linked to the backport of "mptcp: pm:
re-using ID of unused removed ADD_ADDR" where this patch depends on
86e39e04482b ("mptcp: keep track of local endpoint still available for
each msk"), I don't think we need to backport this patch to v5.15.

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