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 9C1902848AD for ; Tue, 11 Nov 2025 18:53:27 +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=1762887207; cv=none; b=EBTNaWsDtpnyNcAvTzLJu8/JpSj8WPQdYv+Vc6RgzrC7mldLGjYR4ERkp0Uc9AmK8LWnbNfs5nBM1jgg3Gqufj+oj34KT89H+16mQbLcfa0TjG80qMLOgRwJOwiptBE9b9T+W5qF8YJgh1osSRZRo4jP7zAs1Q076j/40k9s3RA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762887207; c=relaxed/simple; bh=b2AOTeQH5gUd5wNgHfaUUO5WBWWvvfHSU4csTs6tqd0=; h=Message-ID:Date:MIME-Version:Subject:From:To:Cc:References: In-Reply-To:Content-Type; b=VljyRJbiXYzsBX0G0LjTQBvXB/BO4EFS2JyosvZ4Ac+qgA0KS7rhBTab8OMlyTZB4SJomhldI4xYiMmVJjVijj5bCWJ8SaWnDKrA/+zSD3GLopTcUDfUVS/ugweMbSeIYuTyRj4QGgLJRT7KWS4+LDIb5itgQHTZMmN05yxf/Uk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZfUmz8BW; 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="ZfUmz8BW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7D212C4CEF5; Tue, 11 Nov 2025 18:53:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762887207; bh=b2AOTeQH5gUd5wNgHfaUUO5WBWWvvfHSU4csTs6tqd0=; h=Date:Subject:From:To:Cc:References:In-Reply-To:From; b=ZfUmz8BWkYYiS8UcQUBmxEhqqLzlhsQyVcs0kuTJ41CwYMr2X2cCD1l21lTgvA1pv yRpbV2XfX928nST4ZBUQcUqE3N5V2PTWqjAaVBpysuR/KiwNf+IXvAJ+YyYpEc+F2T zbipaxZkqWx4k+WMDESJxgZf7GsojCMkyTdJGWyEfPdqWSAtuHFL1gvZsFE0/sVbPV uHH1agjWdJmR+Xm9y1mQoEiSreBW+0JQpGqPUAImeRks+ktUvUsOxBWuF3LYiDlLjH skbRJGdPiffTmKFg8BN32A1Jv0ka4Jljr5JB91XF5DU5VhUnZZWBoE8LzETubKepLu 4X57dKD8vOOnQ== Message-ID: <127e3172-3a82-4286-a095-b8cf884df056@kernel.org> Date: Tue, 11 Nov 2025 19:53:24 +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 v3 mptcp-next 2/7] mptcp: avoid unneeded subflow-level drops. Content-Language: en-GB, fr-BE From: Matthieu Baerts To: Paolo Abeni , mptcp@lists.linux.dev Cc: Mat Martineau References: <6af807a4d56bcac85d0908e30251ffa6d28ea38f.1762504059.git.pabeni@redhat.com> Autocrypt: addr=matttbe@kernel.org; keydata= xsFNBFXj+ekBEADxVr99p2guPcqHFeI/JcFxls6KibzyZD5TQTyfuYlzEp7C7A9swoK5iCvf YBNdx5Xl74NLSgx6y/1NiMQGuKeu+2BmtnkiGxBNanfXcnl4L4Lzz+iXBvvbtCbynnnqDDqU c7SPFMpMesgpcu1xFt0F6bcxE+0ojRtSCZ5HDElKlHJNYtD1uwY4UYVGWUGCF/+cY1YLmtfb WdNb/SFo+Mp0HItfBC12qtDIXYvbfNUGVnA5jXeWMEyYhSNktLnpDL2gBUCsdbkov5VjiOX7 CRTkX0UgNWRjyFZwThaZADEvAOo12M5uSBk7h07yJ97gqvBtcx45IsJwfUJE4hy8qZqsA62A nTRflBvp647IXAiCcwWsEgE5AXKwA3aL6dcpVR17JXJ6nwHHnslVi8WesiqzUI9sbO/hXeXw TDSB+YhErbNOxvHqCzZEnGAAFf6ges26fRVyuU119AzO40sjdLV0l6LE7GshddyazWZf0iac nEhX9NKxGnuhMu5SXmo2poIQttJuYAvTVUNwQVEx/0yY5xmiuyqvXa+XT7NKJkOZSiAPlNt6 VffjgOP62S7M9wDShUghN3F7CPOrrRsOHWO/l6I/qJdUMW+MHSFYPfYiFXoLUZyPvNVCYSgs 3oQaFhHapq1f345XBtfG3fOYp1K2wTXd4ThFraTLl8PHxCn4ywARAQABzSRNYXR0aGlldSBC YWVydHMgPG1hdHR0YmVAa2VybmVsLm9yZz7CwZEEEwEIADsCGwMFCwkIBwIGFQoJCAsCBBYC AwECHgECF4AWIQToy4X3aHcFem4n93r2t4JPQmmgcwUCZUDpDAIZAQAKCRD2t4JPQmmgcz33 EACjROM3nj9FGclR5AlyPUbAq/txEX7E0EFQCDtdLPrjBcLAoaYJIQUV8IDCcPjZMJy2ADp7 /zSwYba2rE2C9vRgjXZJNt21mySvKnnkPbNQGkNRl3TZAinO1Ddq3fp2c/GmYaW1NWFSfOmw MvB5CJaN0UK5l0/drnaA6Hxsu62V5UnpvxWgexqDuo0wfpEeP1PEqMNzyiVPvJ8bJxgM8qoC cpXLp1Rq/jq7pbUycY8GeYw2j+FVZJHlhL0w0Zm9CFHThHxRAm1tsIPc+oTorx7haXP+nN0J iqBXVAxLK2KxrHtMygim50xk2QpUotWYfZpRRv8dMygEPIB3f1Vi5JMwP4M47NZNdpqVkHrm jvcNuLfDgf/vqUvuXs2eA2/BkIHcOuAAbsvreX1WX1rTHmx5ud3OhsWQQRVL2rt+0p1DpROI 3Ob8F78W5rKr4HYvjX2Inpy3WahAm7FzUY184OyfPO/2zadKCqg8n01mWA9PXxs84bFEV2mP VzC5j6K8U3RNA6cb9bpE5bzXut6T2gxj6j+7TsgMQFhbyH/tZgpDjWvAiPZHb3sV29t8XaOF BwzqiI2AEkiWMySiHwCCMsIH9WUH7r7vpwROko89Tk+InpEbiphPjd7qAkyJ+tNIEWd1+MlX ZPtOaFLVHhLQ3PLFLkrU3+Yi3tXqpvLE3gO3LM7BTQRV4/npARAA5+u/Sx1n9anIqcgHpA7l 5SUCP1e/qF7n5DK8LiM10gYglgY0XHOBi0S7vHppH8hrtpizx+7t5DBdPJgVtR6SilyK0/mp 9nWHDhc9rwU3KmHYgFFsnX58eEmZxz2qsIY8juFor5r7kpcM5dRR9aB+HjlOOJJgyDxcJTwM 1ey4L/79P72wuXRhMibN14SX6TZzf+/XIOrM6TsULVJEIv1+NdczQbs6pBTpEK/G2apME7vf mjTsZU26Ezn+LDMX16lHTmIJi7Hlh7eifCGGM+g/AlDV6aWKFS+sBbwy+YoS0Zc3Yz8zrdbi Kzn3kbKd+99//mysSVsHaekQYyVvO0KD2KPKBs1S/ImrBb6XecqxGy/y/3HWHdngGEY2v2IP Qox7mAPznyKyXEfG+0rrVseZSEssKmY01IsgwwbmN9ZcqUKYNhjv67WMX7tNwiVbSrGLZoqf Xlgw4aAdnIMQyTW8nE6hH/Iwqay4S2str4HZtWwyWLitk7N+e+vxuK5qto4AxtB7VdimvKUs x6kQO5F3YWcC3vCXCgPwyV8133+fIR2L81R1L1q3swaEuh95vWj6iskxeNWSTyFAVKYYVskG V+OTtB71P1XCnb6AJCW9cKpC25+zxQqD2Zy0dK3u2RuKErajKBa/YWzuSaKAOkneFxG3LJIv Hl7iqPF+JDCjB5sAEQEAAcLBXwQYAQIACQUCVeP56QIbDAAKCRD2t4JPQmmgc5VnD/9YgbCr HR1FbMbm7td54UrYvZV/i7m3dIQNXK2e+Cbv5PXf19ce3XluaE+wA8D+vnIW5mbAAiojt3Mb 6p0WJS3QzbObzHNgAp3zy/L4lXwc6WW5vnpWAzqXFHP8D9PTpqvBALbXqL06smP47JqbyQxj Xf7D2rrPeIqbYmVY9da1KzMOVf3gReazYa89zZSdVkMojfWsbq05zwYU+SCWS3NiyF6QghbW voxbFwX1i/0xRwJiX9NNbRj1huVKQuS4W7rbWA87TrVQPXUAdkyd7FRYICNW+0gddysIwPoa KrLfx3Ba6Rpx0JznbrVOtXlihjl4KV8mtOPjYDY9u+8x412xXnlGl6AC4HLu2F3ECkamY4G6 UxejX+E6vW6Xe4n7H+rEX5UFgPRdYkS1TA/X3nMen9bouxNsvIJv7C6adZmMHqu/2azX7S7I vrxxySzOw9GxjoVTuzWMKWpDGP8n71IFeOot8JuPZtJ8omz+DZel+WCNZMVdVNLPOd5frqOv mpz0VhFAlNTjU1Vy0CnuxX3AM51J8dpdNyG0S8rADh6C8AKCDOfUstpq28/6oTaQv7QZdge0 JY6dglzGKnCi/zsmp2+1w559frz4+IC7j/igvJGX4KDDKUs0mlld8J2u2sBXv7CGxdzQoHaz lzVbFe7fduHbABmYz9cefQpO7wDE/Q== Organization: NGI0 Core In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/11/2025 19:43, Matthieu Baerts wrote: > Hi Paolo, > > On 07/11/2025 09:32, Paolo Abeni wrote: >> The rcv window is shared among all the subflows. Currently, MPTCP sync >> the TCP-level rcv window with the MPTCP one at tcp_transmit_skb() time. >> >> The above means that incoming data may sporadically observe outdated >> TCP-level rcv window and being wrongly dropped by TCP. >> >> Address the issue checking for the edge condition before queuing the data >> at TCP level, and eventually syncing the rcv window as needed. >> >> Note that the issue is actually present from the very first MPTCP >> implementation, but backports older than the blamed commit below will range >> from impossible to useless. > > Thank you for this patch! > > It looks good to me: > > Reviewed-by: Matthieu Baerts (NGI0) > >> Before: >> nstat >/dev/null ;sleep 1; nstat -z TcpExtBeyondWindow >> TcpExtBeyondWindow 14 0.0 >> >> After: >> nstat >/dev/null ;sleep 1; nstat -z TcpExtBeyondWindow >> TcpExtBeyondWindow 0 0.0 > > Should we eventually track this MIB counter in mptcp_connect.sh? (This can be done in another patch later, we can also create a task to do it later if that's easier of course.) > >> Fixes: fa3fe2b15031 ("mptcp: track window announced to peer") > > While there are still discussions on patch 6/7, to ease things, I > suggest already applying only this patch in our tree (fixes for -net), > the only material for 'net' from what I understood. Done: New patches for t/upstream-net and t/upstream: - 9250eb1bd82b: mptcp: avoid unneeded subflow-level drops - Results: 7d372ea35141..25f5033b9887 (export-net) - Results: 3b1f54eb2ace..3dad323fd8af (export) Tests are now in progress: - export-net: https://github.com/multipath-tcp/mptcp_net-next/commit/ef271ef4961b23166a56d80c5136bb85b29826d8/checks - export: https://github.com/multipath-tcp/mptcp_net-next/commit/473f3b6a6838866eed83d85449df20f654ac4c1a/checks Cheers, Matt -- Sponsored by the NGI0 Core fund.