From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D938830FC04 for ; Wed, 5 Nov 2025 11:22:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762341744; cv=none; b=nhpaEdVCgGq2ImzhmCPR2+NVomsESyaCJ5Xrh7VBMnKsLvIbMHBphQFQV89iBHpX+/cwZi3glgDrS01KGpb4ZhLlDkvmZDZ97oM4lXe16pjoq7hcWyAt9N1D8J1rXX9cV5ckwd+o0S1slDPrAnMvmd1ga7lX8UY6DIhp2g7uk3k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762341744; c=relaxed/simple; bh=uiSHxtgQYFF8G8QPouMD5eHvOXPj2CHUZnPoyjddPJU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Zz0uf9SRHdiy8dIP5z/aU6tyhaBxaFar2jJdJy1JULraKPY2OAzge5QC5a+8spHBDq2XoU+kcfgIxCAwLx2hfeDDkmfnn6mydmioEUM9cWa0b4+Qd7MmV5nlF6kNOIHlm9+vV6TSnIWab7R/WWZWORo5slknq48sPl/arbajLgI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BBoaAYic; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="BBoaAYic" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 580CEC4CEF8; Wed, 5 Nov 2025 11:22:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762341744; bh=uiSHxtgQYFF8G8QPouMD5eHvOXPj2CHUZnPoyjddPJU=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=BBoaAYiceZD3Z3P76EUHdImCF8f3LTT55/qTCVgYUXanOa8mRhrjlc0weo+IiYyUQ E69IhAMcIHvg/62cAcztklggdb+VKa2vMzv3n3tQw/mpG72OAw3jQ8Ap7BtHYBx+Gi v+S+BrzpfBaTOoF2CwoNID5uZe0+erqXoGDJ0n6NS/h5XUaC++yIqau32m0XNjsOpr NMf1qFwZe7uyH0HpoCw1U05Of1zvP4hGaD4UyVxi7gBqtVf+eEPqBXGi8tqQf8ZzBg 6AC97pn93BI8gB7Mqqwtu6ImgL9UkJCcROpCKERPAg9cOQN5gkOqPTd5b7GDpvo8Y/ J+ed8RIAFjrag== Message-ID: Date: Wed, 5 Nov 2025 12:22:20 +0100 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH, mptcp-net] mptcp: fix address removal logic in mptcp_pm_nl_rm_addr Content-Language: en-GB, fr-BE To: GangYan Cc: Gang Yan , mptcp@lists.linux.dev References: <20251104123416.395362-1-gang.yan@linux.dev> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Gang, On 05/11/2025 03:13, GangYan wrote: >> On Tue, Nov 04, 2025 at 03:34:38PM +0100, Matthieu Baerts wrote: >> Hi Gang, >> >> On 04/11/2025 13:34, Gang Yan wrote: >>> From: Gang Yan >>> >>> Fix inverted WARN_ON_ONCE condition that prevented normal address >>> removal counter updates. The current code only executes decrement >>> logic when the counter is already 0 (abnormal state), while >>> normal removals (counter > 0) are ignored. >> >> Good catch! >> >> For fixes, we need a Fixes tag: >> >> Fixes: 636113918508 ("mptcp: pm: remove '_nl' from >> mptcp_pm_nl_rm_addr_received") >> >> Apart from that, it looks good to me: >> >> Reviewed-by: Matthieu Baerts (NGI0) >> >> How did you find out about this? I'm surprised out test suite didn't >> spot it. By chance, do you have a test that can be used to reproduce >> this issue? > > I've been looking into the work_pending-related issue described in > #ISSUE 440 and have designed several potentially affected scenarios > based on mptcp_join tests. Except for the case where endpoints are > deleted one by one and then re-added via ADD_ADDR (which fails), all > other related tests have passed. (I'll share some conclusions in the > corresponding discussion later.) > > By tracing the relevant code, I found that the value of > 'add_addr_accepted' here does not decrease, which subsequently blocks > further ADD_ADDR operations. We can verify the value of > 'add_addr_accepted' in 'delete re-add signal' test, which can be found > in mptcp_join.sh, using either 'ss' or 'mptcp_diag'. The reason this > test didn't fail previously is that when the 'add_addr_accepted_limit' > was set to 3, the test's add_addr operations never reached the limit, > so no overflow occurred. OK, so the WARN_ON_ONCE() is not shown because add_addr_accepted is never decremented, but it should have been decremented (not below the limit). > I lean toward using 'ss' to obtain the token and then retrieving the > 'add_addr_accepted' value via 'mptcp_diag', because when the value is > zero, ss does not display it. Moreover, using 'mptcp_diag' minimizes > potential inconsistencies caused by different versions of iproute2, > making maintenance easier. WDYT? I think you can use 'ss', because it is already used in this test, see chk_mptcp_info(). I suggest applying the fix now, the test can be added later. Cheers, Matt -- Sponsored by the NGI0 Core fund.