From patchwork Mon May 20 08:16:40 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthieu Baerts X-Patchwork-Id: 13668125 X-Patchwork-Delegate: kuba@kernel.org 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 1C13A1CD20; Mon, 20 May 2024 08:17:08 +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=1716193029; cv=none; b=I6K2NsE8mF9BIEjvvWz8S7yAzzenVmjINe+yH0/rJhnRUPrl+wjKwby5qAKVzX5So6Ex0xz58lsc3NGsBWq2WQqQfcbo+u/OCMegu7sAvn1//RBb0LsjKzhBByoA1FOsoHWe2DGnsPk2gjuxaBnij6o0E3XMpsqHMOXDU2mHgik= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716193029; c=relaxed/simple; bh=ypvHqt2ffZwH1g8JlbofDCv9yboiuwJHzR7LWZNKd+E=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=aryjOQ9Yu/HlCGderBXeaIVLPLc7Zub0ZuSDedYrwEN3M+8Y/02g007lZvCQ8uWS3qgUCe+RJd2MPnWGPgkq5D657uEgKCzDR1OkN6ng0Fgyy6NpHAsdL40N4ra0sWt/jTAGgWoT+pCLhES7+q9d195hdvE8kCV/bTI7Tvfvr3g= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qDByjCIU; 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="qDByjCIU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E10E1C32789; Mon, 20 May 2024 08:17:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1716193028; bh=ypvHqt2ffZwH1g8JlbofDCv9yboiuwJHzR7LWZNKd+E=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=qDByjCIUbE3VQPYSTLOsc5/m81cIewKVi/BdaSB/onZnBL76JIXXH2/91oKu6agDe YQe0QyAhVGLp4L4ko+ztAfGznFthHRycvo5CYvL6oslP77DfAXn35kycD7di1gQrbo jx/gyxY56bi/TbBMfLMKRZeDGvMXUpgp7qPSBVwP+ulj+Vh5JqjfEs5Ko5KUaiPe00 Ge5JqphKOmZZH/KUoARRqr65sDrMmLSKId6Uhs/Yntc4Ox1o3/E0+II/PhTWCPzuhr ktEdkqxGgSTDak4McedKpX+3DodVtIDXzdTnIm0YS7cLWm42pnj0/sfsb8eDu8t8Xe rZ0hJO0J0zEHA== From: "Matthieu Baerts (NGI0)" Date: Mon, 20 May 2024 10:16:40 +0200 Subject: [PATCH net 1/3] doc: mptcp: add missing 'available_schedulers' entry Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20240520-upstream-net-20240520-mptcp-doc-v1-1-e3ad294382cb@kernel.org> References: <20240520-upstream-net-20240520-mptcp-doc-v1-0-e3ad294382cb@kernel.org> In-Reply-To: <20240520-upstream-net-20240520-mptcp-doc-v1-0-e3ad294382cb@kernel.org> To: mptcp@lists.linux.dev, Mat Martineau , Geliang Tang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Jonathan Corbet , Gregory Detal Cc: netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, "Matthieu Baerts (NGI0)" X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=988; i=matttbe@kernel.org; h=from:subject:message-id; bh=ypvHqt2ffZwH1g8JlbofDCv9yboiuwJHzR7LWZNKd+E=; b=owEBbQKS/ZANAwAIAfa3gk9CaaBzAcsmYgBmSwb+NBJUXiInrG2pnMi0PXYho+FsHl1vTXe0U lglvYxs5iCJAjMEAAEIAB0WIQToy4X3aHcFem4n93r2t4JPQmmgcwUCZksG/gAKCRD2t4JPQmmg c29ZD/0egHdO5nzQbogETrEz70f9W4t6nMXYznkP3a4mWjjnuKQqJ6wc3pOS2JEYa3Qbkc0PQRa Ps3Lg++2gHP8NSkIilMwH4OszC+cJjKkCcMfG4jAVorInSlaoG0L+TP+hXgNp8egiCzcJgWT8uC xRdkSzFsw11F1FTtotPqnc3dCT5J9lkJKFjfB0rKFCNjs6rvzzINRYjKtErwHBOR4P+SObisn02 /yCRxpYMeG2NmlKFwf/B1gKCMo0eibL2/X77ySRekPgcfnjfS+kTLom5tTsPO2HATHXbuOlUCfD eJ8PID+G8hKFUanZ6+9v+DbcSgP7TRxZTrwpE9qbh+ZEhEtVuopnE6NxezAOeYXVHD2y6bZWSwt PHdvTJL9V4ki4P/M1XqJNTwvO7oKjcAJpm3zZ+J6Aco4xiYFdE+KDTux+xdCqClt0MERam5uIZe vjQmMCcgD4Xwo7J2J/lbRZvCcORMl7RBjlPuhCbzp5XFVfjpoLWviHz7h4l9ZNxaJ97pcUiCWTC ifPSfCrdUbMcjOh5zLE1Fmo89UGzHQmdDzI013oPZDvCHcJ+XgXx+LKm7YGhdjGQD62w594jLHk Q4Oiuah6sjj3TrXLFOSV4kMnGmd0Vx5G52DCxykBn985agcFHYYOhJKNOo0R3ZxpXeGoFxnGsxf QiJNyQr2cLpNSkQ== X-Developer-Key: i=matttbe@kernel.org; a=openpgp; fpr=E8CB85F76877057A6E27F77AF6B7824F4269A073 X-Patchwork-Delegate: kuba@kernel.org This sysctl knob has been added recently, but the documentation has not been updated. This knob is used to show the available schedulers choices that are registered, similar to 'net.ipv4.tcp_available_congestion_control'. Fixes: 73c900aa3660 ("mptcp: add net.mptcp.available_schedulers") Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) --- Documentation/networking/mptcp-sysctl.rst | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/Documentation/networking/mptcp-sysctl.rst b/Documentation/networking/mptcp-sysctl.rst index 69975ce25a02..102a45e7bfa8 100644 --- a/Documentation/networking/mptcp-sysctl.rst +++ b/Documentation/networking/mptcp-sysctl.rst @@ -93,3 +93,7 @@ scheduler - STRING sysctl. Default: "default" + +available_schedulers - STRING + Shows the available schedulers choices that are registered. More packet + schedulers may be available, but not loaded. From patchwork Mon May 20 08:16:41 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthieu Baerts X-Patchwork-Id: 13668126 X-Patchwork-Delegate: kuba@kernel.org 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 29D38225CE; Mon, 20 May 2024 08:17:11 +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=1716193032; cv=none; b=cDEO5Pm/v90JZ5OrBfdfi6xNUDXBemdHFn3sK7mRvMVrwYT3vEudOVBUT8OxsNBq15MR6/M2NMRXFhIpBnkEfkLJMa+Y3fYuC/fR+wq8AkpePGfjgz74oINqFpMTyUBoD0tZIEtCl9tudEWVTgTFuH5f7lE6BczjnRCyNKBOHf8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716193032; c=relaxed/simple; bh=l9P1LJpRFXGmNv34bk5f33fH/TJc9InrPPq2VO+kELI=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=J6G5cBS9JXOD7HfzlA85R9QMQqQIEsL2i8jlWWmtNSj62s1/PZypNSZCiB42RK2ARxygZk9CRtJt/fyMzLTpY66G0S1YHmCwAZrA5wXA5t9vnHhEFfgP8XJRvz8roZuUQh8umWyx61DtubBPguN3lFv+EItrXBDvJpk3ApoJb3o= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fTTfvIhL; 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="fTTfvIhL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0BB83C2BD10; Mon, 20 May 2024 08:17:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1716193031; bh=l9P1LJpRFXGmNv34bk5f33fH/TJc9InrPPq2VO+kELI=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=fTTfvIhLPVwBqDSExH+smCvWBQH0pQ2ZlJg56HxsmlZXIFGUw5JaLYry6Lt3966le tWNOBfLKmsoY570J0dlh+IyeG+n+sVfxv9/nHMDC9ucFZexXX89h7izo3fw/bFjvtw iUlQgZsiB8bH7DaVXxwRRvu7lUTV/loNkwAGAya0gxj5J5tGEC0WEOzrMgEV/3/ZCM Eq7bRzSk2AJHR00oia7UjqcnEiqQkJ3ZGe0sbvbGyB0XGQD3qsfw8OEk4rtPvaelCE 7QTzLTF1Vouq7YY41E5Hhd7YZb9WDjNBYkrpCqvmYZgl7E9al/8Pl4sVXMgjtBiVc1 2k612T0J+dtIw== From: "Matthieu Baerts (NGI0)" Date: Mon, 20 May 2024 10:16:41 +0200 Subject: [PATCH net 2/3] doc: mptcp: alphabetical order Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20240520-upstream-net-20240520-mptcp-doc-v1-2-e3ad294382cb@kernel.org> References: <20240520-upstream-net-20240520-mptcp-doc-v1-0-e3ad294382cb@kernel.org> In-Reply-To: <20240520-upstream-net-20240520-mptcp-doc-v1-0-e3ad294382cb@kernel.org> To: mptcp@lists.linux.dev, Mat Martineau , Geliang Tang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Jonathan Corbet , Gregory Detal Cc: netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, "Matthieu Baerts (NGI0)" X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=4118; i=matttbe@kernel.org; h=from:subject:message-id; bh=l9P1LJpRFXGmNv34bk5f33fH/TJc9InrPPq2VO+kELI=; b=owEBbQKS/ZANAwAIAfa3gk9CaaBzAcsmYgBmSwb+39t4mSMK2P+yWtgxNepqakoh7IQVVPGdm HF2XiuK0+CJAjMEAAEIAB0WIQToy4X3aHcFem4n93r2t4JPQmmgcwUCZksG/gAKCRD2t4JPQmmg cxirEAClGi5n9IQf0isntmYkTaN13mXZU6bfNyWgnHjLgND25t5QMztWDoJuTQjWzFyQD+rzDfG LDK5acAAhFV6bL9riNbZrUGpAwOP07ybywpYEgpVvohZ6j1KsDGT159JgvsmBNi9VLoZh6tqgeY 5+Hncx7aocVHIvxb2PQlVuJVqjqfPcG+NK3XlmgfrTl9RTRTgTWAoOgLwBD+3oraKPDkDZ2OjCH i8Pyx9sjMnsnQXv/TvQm2dQH7YglVbx2jKEyVlDlDz05eK2MQutTtiijpt717eqyBJDt8DkJYYK thyD3krOUXybWRzhVSuqSlTSShk+BPBRgjyl1MJzt+uDUmEKSQ+hYSFzaJUcwt24sDOknU/Jrq2 IqhYhcBVtYArwqrVgGpPrhL7geOqFE3+XNq53pcKJXKPfRIPGGqbIIgaS18k6PUdvpszN9naYAU yBxuy/i8dxcPemxOvY05vejLcjrK2AiQSuIStFgVYp9AWV5nl4qGjJy+yK4bC0rq9mNphM+lx5H WIHzfOaINpeGk9ycHsGGEvDw6Z+BrQviHUOORePyD2W7VYInJ5C97sUCjRpp0ZFsbrKhoCQSmN/ 8o58GxVSNclwHNNoT/NAsWTEFPTSRjp23i69Pum3RU2QdX++UvIHRVclHU7TUUrQ1O5cAq5+HZs 67uH4fEZPm01jlQ== X-Developer-Key: i=matttbe@kernel.org; a=openpgp; fpr=E8CB85F76877057A6E27F77AF6B7824F4269A073 X-Patchwork-Delegate: kuba@kernel.org Similar to what is done in other 'sysctl' pages: it looks clearer from a readability perspective. This might cause troubles in the short/mid-term with the backports, but by not putting new entries at the end, this can help to reduce conflicts in case of backports in the long term. We don't change the information here too often, so it looks OK to do that. Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) --- Documentation/networking/mptcp-sysctl.rst | 78 +++++++++++++++---------------- 1 file changed, 39 insertions(+), 39 deletions(-) diff --git a/Documentation/networking/mptcp-sysctl.rst b/Documentation/networking/mptcp-sysctl.rst index 102a45e7bfa8..fd514bba8c43 100644 --- a/Documentation/networking/mptcp-sysctl.rst +++ b/Documentation/networking/mptcp-sysctl.rst @@ -7,14 +7,6 @@ MPTCP Sysfs variables /proc/sys/net/mptcp/* Variables =============================== -enabled - BOOLEAN - Control whether MPTCP sockets can be created. - - MPTCP sockets can be created if the value is 1. This is a - per-namespace sysctl. - - Default: 1 (enabled) - add_addr_timeout - INTEGER (seconds) Set the timeout after which an ADD_ADDR control message will be resent to an MPTCP peer that has not acknowledged a previous @@ -25,25 +17,6 @@ add_addr_timeout - INTEGER (seconds) Default: 120 -close_timeout - INTEGER (seconds) - Set the make-after-break timeout: in absence of any close or - shutdown syscall, MPTCP sockets will maintain the status - unchanged for such time, after the last subflow removal, before - moving to TCP_CLOSE. - - The default value matches TCP_TIMEWAIT_LEN. This is a per-namespace - sysctl. - - Default: 60 - -checksum_enabled - BOOLEAN - Control whether DSS checksum can be enabled. - - DSS checksum can be enabled if the value is nonzero. This is a - per-namespace sysctl. - - Default: 0 - allow_join_initial_addr_port - BOOLEAN Allow peers to send join requests to the IP address and port number used by the initial subflow if the value is 1. This controls a flag that is @@ -57,6 +30,37 @@ allow_join_initial_addr_port - BOOLEAN Default: 1 +available_schedulers - STRING + Shows the available schedulers choices that are registered. More packet + schedulers may be available, but not loaded. + +checksum_enabled - BOOLEAN + Control whether DSS checksum can be enabled. + + DSS checksum can be enabled if the value is nonzero. This is a + per-namespace sysctl. + + Default: 0 + +close_timeout - INTEGER (seconds) + Set the make-after-break timeout: in absence of any close or + shutdown syscall, MPTCP sockets will maintain the status + unchanged for such time, after the last subflow removal, before + moving to TCP_CLOSE. + + The default value matches TCP_TIMEWAIT_LEN. This is a per-namespace + sysctl. + + Default: 60 + +enabled - BOOLEAN + Control whether MPTCP sockets can be created. + + MPTCP sockets can be created if the value is 1. This is a + per-namespace sysctl. + + Default: 1 (enabled) + pm_type - INTEGER Set the default path manager type to use for each new MPTCP socket. In-kernel path management will control subflow @@ -74,6 +78,14 @@ pm_type - INTEGER Default: 0 +scheduler - STRING + Select the scheduler of your choice. + + Support for selection of different schedulers. This is a per-namespace + sysctl. + + Default: "default" + stale_loss_cnt - INTEGER The number of MPTCP-level retransmission intervals with no traffic and pending outstanding data on a given subflow required to declare it stale. @@ -85,15 +97,3 @@ stale_loss_cnt - INTEGER This is a per-namespace sysctl. Default: 4 - -scheduler - STRING - Select the scheduler of your choice. - - Support for selection of different schedulers. This is a per-namespace - sysctl. - - Default: "default" - -available_schedulers - STRING - Shows the available schedulers choices that are registered. More packet - schedulers may be available, but not loaded. From patchwork Mon May 20 08:16:42 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthieu Baerts X-Patchwork-Id: 13668127 X-Patchwork-Delegate: kuba@kernel.org 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 ED96D28DC3; Mon, 20 May 2024 08:17:14 +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=1716193035; cv=none; b=Jn23H0eSPF5JgrlwfmNUiQxNKrFzYiWeG3lbxWyxFyygpIRCoqUySU7CxwTXvISQMx/qMPyByIp7JHa6JSDuNNQWi6CaWuwb5p4ihqs1yaluCOkPraifeYDV6qro2UdnYs7l2v9Y39Lc6vFPeKQ2xUGvmOYlXf4VwGQAlHUcDas= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716193035; c=relaxed/simple; bh=QgCL0TznUXYUq/InihcUj2cppYGX07y3mYRc9yDHdIA=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=gfBbK/aHAV5S6k5tcIKqG1BweF9fRJRTJOwvlKSVPIg1nlpXDyvG0ViqYvxyyTgNh/PfzeZkygT4Qj3CnQt2GRl8tp7PTrlMP+htkfPC+EsNeSm+M1dmLLtchwdunFNuxL4w9ul7K6BHqpfNV3BxYFLJtqIbiGfQEzpN1eEDORI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=X8fERONQ; 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="X8fERONQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2AA46C4AF0B; Mon, 20 May 2024 08:17:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1716193034; bh=QgCL0TznUXYUq/InihcUj2cppYGX07y3mYRc9yDHdIA=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=X8fERONQU3Uz5bCnaNXlqPsawbcy1UeDMdPAa1z+PpjLQNdoiTd7++vMvbLYkx6re 1DYYVlLnHe1kKFWxso6nYrbPosxeubNIb/17SuasXUjKXFpS/hkyXbgpFkgSGm6Dy/ 6jodx4jRrJz52QAFZ+AKgCfzOecj6ddtwfkjJtHVzIuR069nx4jerEOOcWeDHdLI15 /6uCMdkB5yqnxLfjATOiFIz1MEqf2+feL40swrDkhNzzs4ebEH/LOQdr7hShH3/xcy P/vENJuXRr0rGkD8kZ1/qLBG54tD8Cww+x87lvOK8yHtV8zVa2y+IqPGVTSWXt9CLb RBRLn/zwUWBKA== From: "Matthieu Baerts (NGI0)" Date: Mon, 20 May 2024 10:16:42 +0200 Subject: [PATCH net 3/3] doc: new 'mptcp' page in 'networking' Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20240520-upstream-net-20240520-mptcp-doc-v1-3-e3ad294382cb@kernel.org> References: <20240520-upstream-net-20240520-mptcp-doc-v1-0-e3ad294382cb@kernel.org> In-Reply-To: <20240520-upstream-net-20240520-mptcp-doc-v1-0-e3ad294382cb@kernel.org> To: mptcp@lists.linux.dev, Mat Martineau , Geliang Tang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Jonathan Corbet , Gregory Detal Cc: netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, "Matthieu Baerts (NGI0)" X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=8560; i=matttbe@kernel.org; h=from:subject:message-id; bh=QgCL0TznUXYUq/InihcUj2cppYGX07y3mYRc9yDHdIA=; b=owEBbQKS/ZANAwAIAfa3gk9CaaBzAcsmYgBmSwb+/gJu3bhoPOLt27/fXN3OcVOaYl6zdpE5G wwQnPYy8/GJAjMEAAEIAB0WIQToy4X3aHcFem4n93r2t4JPQmmgcwUCZksG/gAKCRD2t4JPQmmg c4PaD/9yuEGMPjHoR7ggq7H+t+dBACiDAgrzA8Vq9wzuTLrt59IilXQ8j1cBEuo07Xn0YvBjCq7 v2oywkVeml6qg9X+H3PKIoD9KqP2MmxBxjaKZTkFIYi7UP22YZAunwTf7P51Nip1kQ6BDqGpWq9 TSAzMa9QfnuvMzgcqhqcalr4WSp96vKrprYP422tuKW76XqMrPNFbhRM7L/6LtnTyWvihvCSb6g 8NJmCqmitesvXX8rxMtQy0IqG/dy6U1os/HfdWzKHmfzNRvv8/NpMnvLl2YjHvnCWWZzWjuuaZ4 nF0lTJy/Q91b7uS9MffY53ISbcTItNY9qnRak9PT/O5rK2FKL0PmwSfj5nBEk6saKM4LnkevE6S U3hIZSStLiKlNUKEo0C+hCdjSu7tPjSfrLSo2f3xONXnsNkVvx5xL6Z+GMCGpG8RiiydXiJ/che QhHxk5HbEIKhCvrzsKmKX3rT1uL3S/ZEQKkNvgOVPQoIxLmkgsinDs17nq9qdJkDMfkcMfecVSa QHZ6FoelwC1PUiY+ybnMTt/i4RmdtTRVWGTdRmBmgR9tR/PDOI9cNizEjW42koFX1fkL6P/rjy6 Imsnj675QsXpF2qMgz9w3gWQqhFNxe72w2/v81vhFOSyNFt/LRnw1qQTugYChhw8akN3dCzVO5u kp5dNHXn4Ua84Gg== X-Developer-Key: i=matttbe@kernel.org; a=openpgp; fpr=E8CB85F76877057A6E27F77AF6B7824F4269A073 X-Patchwork-Delegate: kuba@kernel.org A general documentation about MPTCP was missing since its introduction in v5.6. Most of what is there comes from our recently updated mptcp.dev website, with additional links to resources from the kernel documentation. This is a first version, mainly targeting app developers and users. Link: https://www.mptcp.dev Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) --- Documentation/networking/index.rst | 1 + Documentation/networking/mptcp.rst | 156 +++++++++++++++++++++++++++++++++++++ MAINTAINERS | 2 +- 3 files changed, 158 insertions(+), 1 deletion(-) diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst index 7664c0bfe461..a6443851a142 100644 --- a/Documentation/networking/index.rst +++ b/Documentation/networking/index.rst @@ -72,6 +72,7 @@ Contents: mac80211-injection mctp mpls-sysctl + mptcp mptcp-sysctl multiqueue multi-pf-netdev diff --git a/Documentation/networking/mptcp.rst b/Documentation/networking/mptcp.rst new file mode 100644 index 000000000000..d31c6b7157fc --- /dev/null +++ b/Documentation/networking/mptcp.rst @@ -0,0 +1,156 @@ +.. SPDX-License-Identifier: GPL-2.0 + +===================== +Multipath TCP (MPTCP) +===================== + +Introduction +============ + +Multipath TCP or MPTCP is an extension to the standard TCP and is described in +`RFC 8684 (MPTCPv1) `_. It allows a +device to make use of multiple interfaces at once to send and receive TCP +packets over a single MPTCP connection. MPTCP can aggregate the bandwidth of +multiple interfaces or prefer the one with the lowest latency, it also allows a +fail-over if one path is down, and the traffic is seamlessly reinjected on other +paths. + +For more details about Multipath TCP in the Linux kernel, please see the +official website: `mptcp.dev `. + + +Use cases +========= + +Thanks to MPTCP, being able to use multiple paths in parallel or simultaneously +brings new use-cases, compared to TCP: + +- Seamless handovers: switching from one path to another while preserving + established connections, e.g. to be used in mobility use-cases, like on + smartphones. +- Best network selection: using the "best" available path depending on some + conditions, e.g. latency, losses, cost, bandwidth, etc. +- Network aggregation: using multiple paths at the same time to have a higher + throughput, e.g. to combine fixed and mobile networks to send files faster. + + +Concepts +======== + +Technically, when a new socket is created with the ``IPPROTO_MPTCP`` protocol +(Linux-specific), a *subflow* (or *path*) is created. This *subflow* consists of +a regular TCP connection that is used to transmit data through one interface. +Additional *subflows* can be negotiated later between the hosts. For the remote +host to be able to detect the use of MPTCP, a new field is added to the TCP +*option* field of the underlying TCP *subflow*. This field contains, amongst +other things, a ``MP_CAPABLE`` option that tells the other host to use MPTCP if +it is supported. If the remote host or any middlebox in between does not support +it, the returned ``SYN+ACK`` packet will not contain MPTCP options in the TCP +*option* field. In that case, the connection will be "downgraded" to plain TCP, +and it will continue with a single path. + +This behavior is made possible by two internal components: the path manager, and +the packet scheduler. + +Path Manager +------------ + +The Path Manager is in charge of *subflows*, from creation to deletion, and also +address announcements. Typically, it is the client side that initiates subflows, +and the server side that announces additional addresses via the ``ADD_ADDR`` and +``REMOVE_ADDR`` options. + +Path managers are controlled by the ``net.mptcp.pm_type`` sysctl knob -- see +mptcp-sysctl.rst. There are two types: the in-kernel one (type ``0``) where the +same rules are applied for all the connections (see: ``ip mptcp``) ; and the +userspace one (type ``1``), controlled by a userspace daemon (i.e. `mptcpd +`_) where different rules can be applied for each +connection. The path managers can be controlled via a Netlink API, see +netlink_spec/mptcp_pm.rst. + +To be able to use multiple IP addresses on a host to create multiple *subflows* +(paths), the default in-kernel MPTCP path-manager needs to know which IP +addresses can be used. This can be configured with ``ip mptcp endpoint`` for +example. + +Packet Scheduler +---------------- + +The Packet Scheduler is in charge of selecting which available *subflow(s)* to +use to send the next data packet. It can decide to maximize the use of the +available bandwidth, only to pick the path with the lower latency, or any other +policy depending on the configuration. + +Packet schedulers are controlled by the ``net.mptcp.scheduler`` sysctl knob -- +see mptcp-sysctl.rst. + + +Sockets API +=========== + +Creating MPTCP sockets +---------------------- + +On Linux, MPTCP can be used by selecting MPTCP instead of TCP when creating the +``socket``: + +.. code-block:: C + + int sd = socket(AF_INET(6), SOCK_STREAM, IPPROTO_MPTCP); + +Note that ``IPPROTO_MPTCP`` is defined as ``262``. + +If MPTCP is not supported, ``errno`` will be set to: + +- ``EINVAL``: (*Invalid argument*): MPTCP is not available, on kernels < 5.6. +- ``EPROTONOSUPPORT`` (*Protocol not supported*): MPTCP has not been compiled, + on kernels >= v5.6. +- ``ENOPROTOOPT`` (*Protocol not available*): MPTCP has been disabled using + ``net.mptcp.enabled`` sysctl knob, see mptcp-sysctl.rst. + +MPTCP is then opt-in: applications need to explicitly request it. Note that +applications can be forced to use MPTCP with different techniques, e.g. +``LD_PRELOAD`` (see ``mptcpize``), eBPF (see ``mptcpify``), SystemTAP, +``GODEBUG`` (``GODEBUG=multipathtcp=1``), etc. + +Switching to ``IPPROTO_MPTCP`` instead of ``IPPROTO_TCP`` should be as +transparent as possible for the userspace applications. + +Socket options +-------------- + +MPTCP supports most socket options handled by TCP. It is possible some less +common options are not supported, but contributions are welcome. + +Generally, the same value is propagated to all subflows, including the ones +created after the calls to ``setsockopt()``. eBPF can be used to set different +values per subflow. + +There are some MPTCP specific socket options at the ``SOL_MPTCP`` (284) level to +retrieve info. They fill the ``optval`` buffer of the ``getsockopt()`` system +call: + +- ``MPTCP_INFO``: Uses ``struct mptcp_info``. +- ``MPTCP_TCPINFO``: Uses ``struct mptcp_subflow_data``, followed by an array of + ``struct tcp_info``. +- ``MPTCP_SUBFLOW_ADDRS``: Uses ``struct mptcp_subflow_data``, followed by an + array of ``mptcp_subflow_addrs``. +- ``MPTCP_FULL_INFO``: Uses ``struct mptcp_full_info``, with one pointer to an + array of ``struct mptcp_subflow_info`` (including the + ``struct mptcp_subflow_addrs``), and one pointer to an array of + ``struct tcp_info``, followed by the content of ``struct mptcp_info``. + +Note that at the TCP level, ``TCP_IS_MPTCP`` socket option can be used to know +if MPTCP is currently being used: the value will be set to 1 if it is. + + +Design choices +============== + +A new socket type has been added for MPTCP for the userspace-facing socket. The +kernel is in charge of creating subflow sockets: they are TCP sockets where the +behavior is modified using TCP-ULP. + +MPTCP listen sockets will create "plain" *accepted* TCP sockets if the +connection request from the client didn't ask for MPTCP, making the performance +impact minimal when MPTCP is enabled by default. diff --git a/MAINTAINERS b/MAINTAINERS index 3fdc3b09c171..4f4a59820e90 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -15673,7 +15673,7 @@ B: https://github.com/multipath-tcp/mptcp_net-next/issues T: git https://github.com/multipath-tcp/mptcp_net-next.git export-net T: git https://github.com/multipath-tcp/mptcp_net-next.git export F: Documentation/netlink/specs/mptcp_pm.yaml -F: Documentation/networking/mptcp-sysctl.rst +F: Documentation/networking/mptcp*.rst F: include/net/mptcp.h F: include/trace/events/mptcp.h F: include/uapi/linux/mptcp*.h