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 73B632F0C69 for ; Thu, 10 Jul 2025 17:41:07 +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=1752169267; cv=none; b=hqysUQ1D0HWJfOG6DA6Sm6wJJoFWCYQ48bUYjcycmJth+niyisnKjqre+O8ufECQRHAOZDSdV6Ivo8xjckhrC3VRC3SX++k5ItzScpMNhs0veuL33DnLBEr7NfnTzIi8QvI7V52vgNs1JGmJ2EXjABXVhYBXmVc2CCATupjEhIc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752169267; c=relaxed/simple; bh=DU/8cCiAoy6NNwwEpARrxq+mWERWbXYzsigUker0jTQ=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=fjLKLgOB1BO+bMzR7swQLeNWuEGZgAvLi515LIVUozPmfDw3eb81+w+Y5Q0VNmrrXd7uzgdyvzS1ktJB74OTZtOKW4rtjJx13teHY3Lr0SvRc2t/CubiBIh3Q8dMxYkVmO+7lcVH24UDzEFG03eipndMpVS6YoaOrfIQVw/Mb4I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IHUGPlKC; 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="IHUGPlKC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6F42EC4CEE3; Thu, 10 Jul 2025 17:41:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752169267; bh=DU/8cCiAoy6NNwwEpARrxq+mWERWbXYzsigUker0jTQ=; h=Date:Subject:To:References:From:In-Reply-To:From; b=IHUGPlKCO40eFK7giseZBp01yoS6gnXilV6wQyKk7l8uh5TsWEfgJzPxnZbO+42aP 3xOaGC1O8CDhfPx2nL/fKtYwDWgXdvLlCarp87hSpt+3SdewqZ6mQNWvPiDiTPXUS5 Lz+7toAfry3XKftlA9c6JwgulXXvDoZK2O1zYw7xI2403KaKtSOpbfJwrJaZIoOKL4 y7xBemETtlptlRozZwhumU7qiGd6f0amRryNUJ43F8MCaL5rE2Il5YZmlMVHx33kJ7 Gxo8kCtcIw2lsKONGHm5qAHmF6n+37yFtZZdZsZ4qkIoT7FhVZbzhMtn9ec+8j3/5L 9Rr/+cW/ZWfdw== Message-ID: Date: Thu, 10 Jul 2025 19:41:04 +0200 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 v3 mptcp-net 0/5] mptcp: fix fallback-related races Content-Language: en-GB, fr-BE To: Paolo Abeni , mptcp@lists.linux.dev References: From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Paolo, On 09/07/2025 17:12, Paolo Abeni wrote: > This series contains 3 fixes somewhat related to various races we have > while handling fallback and 2 small follow-up likely more suited for > net-next. > > The root cause of the issues addressed here is that the check for > "we can fallback to tcp now" and the related action are not atomic. That > also applies to fallback due to MP_FAIL - where the window race is even > wider. > > Address the issue introducing an additional spinlock to bundle together > all the relevant events, as per patch 1 and 2. > > Note that mptcp_disconnect() unconditionally > clears the fallback status (zeroing msk->flags) but don't tuch the > `allows_infinite_fallback` flag. Such issue is addressed in patch 3. > > Patch 4 cleans up a bit the fallback code, introducing specific MIB for > each FB reason, and patch 5 drops the, hopefully now redundant > pr_fallback(). > --- > v2 -> v3: > - mptcp_do_fallback -> mptcp_try_fallback > - refactored patch 3/5 > - changed mibs names, increment fail only when the protocol mandate it > - fix W=1 warn in patch 5/5 Thank you for the new version! It looks good to me, I just a few small questions, not really blocking the series, and I can eventually do the small modifications when applying the patches if you prefer. > > Paolo Abeni (5): > mptcp: make fallback action and fallback decision atomic > mptcp: plug races between subflow fail and subflow creation > mptcp: reset fallback status gracefully at disconnect() time > mptcp: track fallbacks accurately via mibs > mptcp: remove pr_fallback() > > net/mptcp/ctrl.c | 4 +- > net/mptcp/mib.c | 5 +++ > net/mptcp/mib.h | 7 ++++ > net/mptcp/options.c | 6 ++- > net/mptcp/pm.c | 8 +++- > net/mptcp/protocol.c | 97 ++++++++++++++++++++++++++++++++++---------- > net/mptcp/protocol.h | 35 ++++++++-------- > net/mptcp/subflow.c | 40 ++++++++++-------- > 8 files changed, 140 insertions(+), 62 deletions(-) > Cheers, Matt -- Sponsored by the NGI0 Core fund.