From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 01143C3A59B for ; Sat, 17 Aug 2019 13:30:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C1CA321019 for ; Sat, 17 Aug 2019 13:30:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="C/sLbIgb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726239AbfHQNax (ORCPT ); Sat, 17 Aug 2019 09:30:53 -0400 Received: from new3-smtp.messagingengine.com ([66.111.4.229]:33691 "EHLO new3-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726191AbfHQNav (ORCPT ); Sat, 17 Aug 2019 09:30:51 -0400 Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailnew.nyi.internal (Postfix) with ESMTP id DF77E20F1; Sat, 17 Aug 2019 09:30:50 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute3.internal (MEProxy); Sat, 17 Aug 2019 09:30:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:date:from :in-reply-to:message-id:mime-version:references:subject:to :x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm3; bh=KKvSdMyusgRmxi3WBUEpj2mLncKCa9vRS/3USrrgzDs=; b=C/sLbIgb wb6MP1levbcxsVmV152NGSYkS79UarkC/JxowAy78E33uXOGZHYtUpoSWwvBOFV1 efaSwuSKwW88RLgV/6/FlsKDRkc8akxHK5FGdYGaxEp3XA0wxxWv00SZ6h5u7WE+ nLN0m8PQYCuHtzAutpnat6jWrXLrf+qHicSpv3mPKlB7U25HJ8ij6xU9fc7gkMnk 6VtabGSdfJ8mbQqwXONnGhqaFFkbktvhTZdGkltt7PBDU6iRzgxvdiRzMgrtq06D oNo5uk4Y0aPmBNIhmQ8Mx0jxQQiNJ8xEP7MrknST1yjmDYBxN3AevZe3akz7ZjD+ Lvam+eiFC2nS2g== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduvddrudefhedgieeiucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucenucfjughrpefhvffufffkofgjfhgggfestdekre dtredttdenucfhrhhomhepkfguohcuufgthhhimhhmvghluceoihguohhstghhsehiugho shgthhdrohhrgheqnecukfhppeejledrudejjedrvddurddukedtnecurfgrrhgrmhepmh grihhlfhhrohhmpehiughoshgthhesihguohhstghhrdhorhhgnecuvehluhhsthgvrhfu ihiivgepke X-ME-Proxy: Received: from splinter.mtl.com (unknown [79.177.21.180]) by mail.messagingengine.com (Postfix) with ESMTPA id 064A780059; Sat, 17 Aug 2019 09:30:46 -0400 (EDT) From: Ido Schimmel To: netdev@vger.kernel.org Cc: davem@davemloft.net, nhorman@tuxdriver.com, jiri@mellanox.com, toke@redhat.com, dsahern@gmail.com, roopa@cumulusnetworks.com, nikolay@cumulusnetworks.com, jakub.kicinski@netronome.com, andy@greyhouse.net, f.fainelli@gmail.com, andrew@lunn.ch, vivien.didelot@gmail.com, mlxsw@mellanox.com, Ido Schimmel Subject: [PATCH net-next v3 10/16] Documentation: Add devlink-trap documentation Date: Sat, 17 Aug 2019 16:28:19 +0300 Message-Id: <20190817132825.29790-11-idosch@idosch.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190817132825.29790-1-idosch@idosch.org> References: <20190817132825.29790-1-idosch@idosch.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Ido Schimmel Add initial documentation of the devlink-trap mechanism, explaining the background, motivation and the semantics of the interface. Signed-off-by: Ido Schimmel Acked-by: Jiri Pirko --- Documentation/networking/devlink-trap.rst | 187 ++++++++++++++++++++++ Documentation/networking/index.rst | 1 + include/net/devlink.h | 6 + 3 files changed, 194 insertions(+) create mode 100644 Documentation/networking/devlink-trap.rst diff --git a/Documentation/networking/devlink-trap.rst b/Documentation/networking/devlink-trap.rst new file mode 100644 index 000000000000..dbc7a3e00fd8 --- /dev/null +++ b/Documentation/networking/devlink-trap.rst @@ -0,0 +1,187 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============ +Devlink Trap +============ + +Background +========== + +Devices capable of offloading the kernel's datapath and perform functions such +as bridging and routing must also be able to send specific packets to the +kernel (i.e., the CPU) for processing. + +For example, a device acting as a multicast-aware bridge must be able to send +IGMP membership reports to the kernel for processing by the bridge module. +Without processing such packets, the bridge module could never populate its +MDB. + +As another example, consider a device acting as router which has received an IP +packet with a TTL of 1. Upon routing the packet the device must send it to the +kernel so that it will route it as well and generate an ICMP Time Exceeded +error datagram. Without letting the kernel route such packets itself, utilities +such as ``traceroute`` could never work. + +The fundamental ability of sending certain packets to the kernel for processing +is called "packet trapping". + +Overview +======== + +The ``devlink-trap`` mechanism allows capable device drivers to register their +supported packet traps with ``devlink`` and report trapped packets to +``devlink`` for further analysis. + +Upon receiving trapped packets, ``devlink`` will perform a per-trap packets and +bytes accounting and potentially report the packet to user space via a netlink +event along with all the provided metadata (e.g., trap reason, timestamp, input +port). This is especially useful for drop traps (see :ref:`Trap-Types`) +as it allows users to obtain further visibility into packet drops that would +otherwise be invisible. + +The following diagram provides a general overview of ``devlink-trap``:: + + Netlink event: Packet w/ metadata + Or a summary of recent drops + ^ + | + Userspace | + +---------------------------------------------------+ + Kernel | + | + +-------+--------+ + | | + | drop_monitor | + | | + +-------^--------+ + | + | + | + +----+----+ + | | Kernel's Rx path + | devlink | (non-drop traps) + | | + +----^----+ ^ + | | + +-----------+ + | + +-------+-------+ + | | + | Device driver | + | | + +-------^-------+ + Kernel | + +---------------------------------------------------+ + Hardware | + | Trapped packet + | + +--+---+ + | | + | ASIC | + | | + +------+ + +.. _Trap-Types: + +Trap Types +========== + +The ``devlink-trap`` mechanism supports the following packet trap types: + + * ``drop``: Trapped packets were dropped by the underlying device. Packets + are only processed by ``devlink`` and not injected to the kernel's Rx path. + The trap action (see :ref:`Trap-Actions`) can be changed. + * ``exception``: Trapped packets were not forwarded as intended by the + underlying device due to an exception (e.g., TTL error, missing neighbour + entry) and trapped to the control plane for resolution. Packets are + processed by ``devlink`` and injected to the kernel's Rx path. Changing the + action of such traps is not allowed, as it can easily break the control + plane. + +.. _Trap-Actions: + +Trap Actions +============ + +The ``devlink-trap`` mechanism supports the following packet trap actions: + + * ``trap``: The sole copy of the packet is sent to the CPU. + * ``drop``: The packet is dropped by the underlying device and a copy is not + sent to the CPU. + +Generic Packet Traps +==================== + +Generic packet traps are used to describe traps that trap well-defined packets +or packets that are trapped due to well-defined conditions (e.g., TTL error). +Such traps can be shared by multiple device drivers and their description must +be added to the following table: + +.. list-table:: List of Generic Packet Traps + :widths: 5 5 90 + + * - Name + - Type + - Description + * - ``source_mac_is_multicast`` + - ``drop`` + - Traps incoming packets that the device decided to drop because of a + multicast source MAC + * - ``vlan_tag_mismatch`` + - ``drop`` + - Traps incoming packets that the device decided to drop in case of VLAN + tag mismatch: The ingress bridge port is not configured with a PVID and + the packet is untagged or prio-tagged + * - ``ingress_vlan_filter`` + - ``drop`` + - Traps incoming packets that the device decided to drop in case they are + tagged with a VLAN that is not configured on the ingress bridge port + * - ``ingress_spanning_tree_filter`` + - ``drop`` + - Traps incoming packets that the device decided to drop in case the STP + state of the ingress bridge port is not "forwarding" + * - ``port_list_is_empty`` + - ``drop`` + - Traps packets that the device decided to drop in case they need to be + flooded and the flood list is empty + * - ``port_loopback_filter`` + - ``drop`` + - Traps packets that the device decided to drop in case after layer 2 + forwarding the only port from which they should be transmitted through + is the port from which they were received + * - ``blackhole_route`` + - ``drop`` + - Traps packets that the device decided to drop in case they hit a + blackhole route + * - ``ttl_value_is_too_small`` + - ``exception`` + - Traps unicast packets that should be forwarded by the device whose TTL + was decremented to 0 or less + * - ``tail_drop`` + - ``drop`` + - Traps packets that the device decided to drop because they could not be + enqueued to a transmission queue which is full + +Generic Packet Trap Groups +========================== + +Generic packet trap groups are used to aggregate logically related packet +traps. These groups allow the user to batch operations such as setting the trap +action of all member traps. In addition, ``devlink-trap`` can report aggregated +per-group packets and bytes statistics, in case per-trap statistics are too +narrow. The description of these groups must be added to the following table: + +.. list-table:: List of Generic Packet Trap Groups + :widths: 10 90 + + * - Name + - Description + * - ``l2_drops`` + - Contains packet traps for packets that were dropped by the device during + layer 2 forwarding (i.e., bridge) + * - ``l3_drops`` + - Contains packet traps for packets that were dropped by the device or hit + an exception (e.g., TTL error) during layer 3 forwarding + * - ``buffer_drops`` + - Contains packet traps for packets that were dropped by the device due to + an enqueue decision diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst index a46fca264bee..86a814e4d450 100644 --- a/Documentation/networking/index.rst +++ b/Documentation/networking/index.rst @@ -14,6 +14,7 @@ Contents: device_drivers/index dsa/index devlink-info-versions + devlink-trap ieee802154 kapi z8530book diff --git a/include/net/devlink.h b/include/net/devlink.h index fb02e0e89f9d..7f43c48f54cd 100644 --- a/include/net/devlink.h +++ b/include/net/devlink.h @@ -540,6 +540,9 @@ struct devlink_trap { u32 metadata_cap; }; +/* All traps must be documented in + * Documentation/networking/devlink-trap.rst + */ enum devlink_trap_generic_id { DEVLINK_TRAP_GENERIC_ID_SMAC_MC, DEVLINK_TRAP_GENERIC_ID_VLAN_TAG_MISMATCH, @@ -556,6 +559,9 @@ enum devlink_trap_generic_id { DEVLINK_TRAP_GENERIC_ID_MAX = __DEVLINK_TRAP_GENERIC_ID_MAX - 1, }; +/* All trap groups must be documented in + * Documentation/networking/devlink-trap.rst + */ enum devlink_trap_group_generic_id { DEVLINK_TRAP_GROUP_GENERIC_ID_L2_DROPS, DEVLINK_TRAP_GROUP_GENERIC_ID_L3_DROPS, -- 2.21.0