From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 16E8E3F9A0D for ; Wed, 27 May 2026 11:35:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779881709; cv=none; b=hLPPt6YFm1Sas9jMGsPM1eKGxQaE0pEHsWWXwCs+rq9rzEsNK1Yot5TzCxe4dpcR956XxO3ePFj3hVLwMFyV+uPUm1k/TF3zcNab1cL4kfaKvFHwMCy0LMipwKh6lxXORDjQjQQ8MlAusFh4YYDJtfgMy8eB27JLdDyUvaJbe58= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779881709; c=relaxed/simple; bh=Cf/O7ai47T7xHejiidVipezGVoG6fw2a4OZEQf2vEJE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=JeTQEdckZyK8CP9gJ5f+0UzOwdCwdd6E9URury7YXT3eLxPlVaxOZ6tufGHDunD7hWS6VQhgtBk7btnGo91gwyAnka4uZVbrnYYivAd8tjI4noAcevjiCEvzgQ5Uy2DECPzcm71GyFuYrD3Sjl0nopgiwMSXLkBocHUwd9NOEIg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kSu4/jF+; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="kSu4/jF+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4CAB31F000E9; Wed, 27 May 2026 11:35:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779881702; bh=eT1Y7QGO2h6bprGPxgQ1iGicUv7k2od6DP0H4fW9gpk=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=kSu4/jF+HAsVXCIT3Y2iv1Fa2Rgkwdkfla9kQ+vWvrbBH6r5skWGW2ncIun9FYQgi drVnuWEiWAtDwVt3MVe0Az/5A3fW5T+nERdvV95fRW9JwV0kp88WMtWlQZXgVZ44D9 KaoIgj+KFeyKLRfUb2mUERzRFqxYYX8NrEAmHpsR70qH6qY27EN/gPV8c9EyYIn926 l09Qsw1feZzyb+RrulT8hXtCRdvY6MO5QkAWhLBRc6sLRPEYOiBcPcu64DnaT99zQv 9I8rasfNKZzVdGPLzB1AzgVxoJKFpPrkIO43Immnwl+ArdkfzfuPJvWLzJEa1BkNT0 ntWhqzFT94Y+A== Message-ID: Date: Wed, 27 May 2026 21:34:58 +1000 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 v4 0/2] mptcp: pm: fix extra_subflows underflow for userspace PM Content-Language: fr To: Tao Cui , geliang@kernel.org Cc: mptcp@lists.linux.dev References: <20260522084658.1896374-1-cuitao@kylinos.cn> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Tao, On 22/05/2026 18:46, Tao Cui wrote: > This is v4 of the series that fixes extra_subflows u8 underflow bugs > in the MPTCP userspace path manager. > > extra_subflows is a u8 field in struct mptcp_pm_data. The userspace PM > increments it after __mptcp_subflow_connect() succeeds, but > __mptcp_subflow_connect() calls mptcp_pm_close_subflow() on failure to > roll back the pre-increment done by the kernel PM. Because the userspace > PM hasn't incremented yet at that point, this decrement is spurious and > causes extra_subflows to underflow from 0 to 255. > > Patch 1 fixes the underflow by aligning the userspace PM with the kernel > PM: increment extra_subflows before calling __mptcp_subflow_connect(), > so the existing error path in subflow.c correctly rolls it back on > failure. This also eliminates the race window described in v3 patch 2 > where the worker could decrement before the user thread increments. > > Patch 2 adds a selftest to validate that subflow creation failure with > an unreachable address does not corrupt the extra_subflows counter. Now in our tree: New patches for t/upstream-net and t/upstream: - 39532fa9ab3a: mptcp: pm: fix extra_subflows underflow on userspace PM subflow creation - f4c28694fcb2: selftests: mptcp: add test for extra_subflows underflow on userspace PM - Results: e4d7ed773e9a..a6fc1cc14ba0 (export-net) - Results: e10477e57c2f..c40ac68d9bc2 (export) Tests are now in progress: - export-net: https://github.com/multipath-tcp/mptcp_net-next/commit/a5802653c80bed89b89dfb2bcf7a1d27a9ccbb05/checks - export: https://github.com/multipath-tcp/mptcp_net-next/commit/c556587fb705370c99b07b8eae2f23e16e6bb145/checks Cheers, Matt -- Sponsored by the NGI0 Core fund.