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From: Matthieu Baerts <matttbe@kernel.org>
To: Tao Cui <cuitao@kylinos.cn>, geliang@kernel.org
Cc: mptcp@lists.linux.dev
Subject: Re: [PATCH mptcp-next] mptcp: pm: add WARN_ON_ONCE guards on extra_subflows underflow
Date: Wed, 26 Aug 2026 15:52:33 +0200	[thread overview]
Message-ID: <5eeb6f1e-3444-4737-a310-dfc0b6b644cd@kernel.org> (raw)
In-Reply-To: <20260522085049.1896537-1-cuitao@kylinos.cn>

Hi Tao,

On 22/05/2026 10:50, Tao Cui wrote:
> extra_subflows is a u8 counter that can underflow if a decrement races
> with or precedes an increment. While the recently fixed userspace PM
> subflow creation path eliminated the primary cause, add defensive
> WARN_ON_ONCE guards at both decrement sites to catch any remaining edge
> cases rather than silently wrapping to 255.

FYI, Clashiko found some existing issues linked to this patch:

https://github.com/multipath-tcp/mptcp_net-next/issues/629

I don't know if it impacts your case, but just to avoid having multiple
people looking at it, do you plan to address Clashiko's comments?

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


  parent reply	other threads:[~2026-08-26 13:52 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-22  8:50 [PATCH mptcp-next] mptcp: pm: add WARN_ON_ONCE guards on extra_subflows underflow Tao Cui
2026-05-22 10:31 ` MPTCP CI
2026-05-27 11:40 ` Matthieu Baerts
2026-08-26 13:52 ` Matthieu Baerts [this message]
2026-08-28  8:33   ` [PATCH net-next 01/11] " Tao Cui
2026-08-28  9:14     ` Matthieu Baerts

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