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 9502F3B2A0 for ; Mon, 27 Oct 2025 12:17:54 +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=1761567474; cv=none; b=rPsaevceMIwBzrD0aUbWoiV8Ivm1ZFgcm+u4dM5/4qLhsD0kRwoRCteHSeV8v+Eseixd0otQTkQBzEoTTP8QseuWePFx7LNx9ICCoz9T3K5cZHYH0z/v8GcdshrDBAACyn5Clv+p/diCivL3eh/eGysSCM0TZb2V9EuQyWkdIxc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761567474; c=relaxed/simple; bh=zNQ08WTwtJw9sIv5R2cLFzJ1npBmiavxkcLNs1oJlcM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=jZHu+Er76ErfcOrLu29dOVKei8Pbm8G8dg2bc+AtnaHPIyjtJ6xY34aOOaNMEefiU/sNg3ToxALZQfGjCPnbCciAc9WbzGh3g/HFyyaXqc3PwQiUED2whB7FfIi4IvC+w5WLSkqYPkg6RfWHrg0tY0htC3E1zmKxvx8vx2Ow1iY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=U3abM8Wh; 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="U3abM8Wh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E0954C4CEF1; Mon, 27 Oct 2025 12:17:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761567474; bh=zNQ08WTwtJw9sIv5R2cLFzJ1npBmiavxkcLNs1oJlcM=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=U3abM8WhFz4hPYCgVCwhR61+pfr0tCb/S+8+HMpzH450aQU7rodeHpUBCUMoORbFy rR7A8X1WAVF+bQciqN8DGBZoj1MzKZPmsiWAm78jRHuqkqnKT+JXay0Ul0OBTjunF2 IMawDRRl0+bnIVXR7RH+9Ljny+Nmi/sxfJ6kf6WGTf7Lp4HYE7U9YCrdcX3ydC8Drm j8sTmtQsT+GknJvYniZDZ3y8qGDSQkbqk55cBo6+t8BizWH7eBA6gD7NFsi4qtuxjb CuVxWGCeo/miJbqcSOuuYNi3xQ883jWJLPzcsfUxVT8EpLUjxPm5stKgfd8qixckKD FBh1c6xSWbEBw== Message-ID: <938a5c96-baf2-46b6-ab3e-cd25d898009e@kernel.org> Date: Mon, 27 Oct 2025 13:17:50 +0100 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 mptcp-next 00/11] mptcp: introduce backlog processing Content-Language: en-GB, fr-BE To: Paolo Abeni , mptcp@lists.linux.dev Cc: Mat Martineau , Geliang Tang References: From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Paolo, On 22/10/2025 16:31, Paolo Abeni wrote: > This series includes RX path improvement built around backlog processing > > The main goals are improving the RX performances _and_ increase the > long term maintainability. > > Patches 2-4 prepare the stack for backlog processing, removing > assumptions that will not hold true anymore after backlog introduction. > > Patches 1 and 5 fixes long standing issues which are quite hard to > reproduce with the current implementation but the 2nd one will become > very apparent with backlog usage. > > Patches 6, 7 and 9 are more cleanups that will make the backlog patch a > little less huge. > > Patch 8 is a somewhat unrelated cleanup, included here before I forgot > about it. > > The real work is done by patch 10 and 11. Patch 10 introduces the helpers > needed to manipulate the msk-level backlog, and the data struct itself, > without any actual functional change. Patch 11 finally use the backlog > for RX skb processing. Note that MPTCP can't uset the sk_backlog, as > the mptcp release callback can also release and re-acquire the msk-level > spinlock and core backlog processing works under the assumption that > such event is not possible. > > A relevant point is memory accounts for skbs in the backlog. > > It's somewhat "original" due to MPTCP constraints. Such skbs use space > from the incoming subflow receive buffer, do not use explicitly any > forward allocated memory, as we can't update the msk fwd mem while > enqueuing, nor we want to acquire again the ssk socket lock while > processing the skbs. > > Instead the msk borrows memory from the subflow and reserve it for > the backlog - see patch 3 and 11 for the gory details. > > Note that even if the skbs can sit in the backlog for an unbounded time, > > --- > v5 -> v6: > - added patch 1/11 > - reworked widely patch 10 && 11 to avoid double accounts for backlog > skb and to address the fwd allocated memory criticality mentioned > in previous iterations. > > Paolo Abeni (11): > mptcp: drop bogus optimization in __mptcp_check_push() > mptcp: borrow forward memory from subflow > mptcp: cleanup fallback data fin reception > mptcp: cleanup fallback dummy mapping generation > mptcp: fix MSG_PEEK stream corruption > mptcp: ensure the kernel PM does not take action too late > mptcp: do not miss early first subflow close event notification. > mptcp: make mptcp_destroy_common() static > mptcp: drop the __mptcp_data_ready() helper > mptcp: introduce mptcp-level backlog > mptcp: leverage the backlog for RX packet processing Sorry for the delay to apply the patches. Now in our tree: New patches for t/upstream-net and t/upstream: - 3a771ce1a023: mptcp: drop bogus optimization in __mptcp_check_push() - b7ad5d80dff9: mptcp: fix MSG_PEEK stream corruption - Results: 2a626f21446a..1ce735a9c1d6 (export-net) - Results: 0d7b92893723..f23a9744c467 (export) Tests are now in progress: - export-net: https://github.com/multipath-tcp/mptcp_net-next/commit/294a632909acc62a7656edc52770f9f59332af39/checks - export: https://github.com/multipath-tcp/mptcp_net-next/commit/1035c9b6c98cf0d15998eb7ce53e5f81621e5116/checks New patches for t/upstream: - f0025b89c22c: mptcp: cleanup fallback data fin reception - 905fec8ceabc: mptcp: cleanup fallback dummy mapping generation - 8b29c30e82d2: mptcp: ensure the kernel PM does not take action too late - 439f10b1648b: mptcp: do not miss early first subflow close event notification - 00804e3abc8d: mptcp: make mptcp_destroy_common() static - 25c9415c554d: mptcp: drop the __mptcp_data_ready() helper - Results: f23a9744c467..eb31e166f63e (export) Tests are now in progress: - export: https://github.com/multipath-tcp/mptcp_net-next/commit/54c37fb023bf32f10f60fb90d27a8fa800de426f/checks Cheers, Matt -- Sponsored by the NGI0 Core fund.