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=-12.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 01CF9C433DB for ; Fri, 15 Jan 2021 19:37:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B505E23877 for ; Fri, 15 Jan 2021 19:37:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388076AbhAOTh6 (ORCPT ); Fri, 15 Jan 2021 14:37:58 -0500 Received: from fllv0015.ext.ti.com ([198.47.19.141]:38910 "EHLO fllv0015.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732952AbhAOTh4 (ORCPT ); Fri, 15 Jan 2021 14:37:56 -0500 Received: from fllv0034.itg.ti.com ([10.64.40.246]) by fllv0015.ext.ti.com (8.15.2/8.15.2) with ESMTP id 10FJZf0h011434; Fri, 15 Jan 2021 13:35:41 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1610739341; bh=DEQ6bZhEA+ydF3cpyj6mYz/unhwgY9HoC1Fw2uxZ3BI=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=V6ukNKUXlSvtX1cUdjJJCrMMZmmfyBLzJZdS/kUvx61LCXhNVb7XeIx8JoS3NSLRH LHLvJW16h8lKG6frO9n5FSjVe6zIAcGeJ58u6A6KjrKVuXSnvzkqf7LlQDhshruQEJ h7v4wL7tESf8ocwmTMTXQufofxCTidjIW/Wxgklw= Received: from DLEE109.ent.ti.com (dlee109.ent.ti.com [157.170.170.41]) by fllv0034.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 10FJZe0k105994 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Fri, 15 Jan 2021 13:35:41 -0600 Received: from DLEE107.ent.ti.com (157.170.170.37) by DLEE109.ent.ti.com (157.170.170.41) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1979.3; Fri, 15 Jan 2021 13:35:40 -0600 Received: from fllv0040.itg.ti.com (10.64.41.20) by DLEE107.ent.ti.com (157.170.170.37) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1979.3 via Frontend Transport; Fri, 15 Jan 2021 13:35:40 -0600 Received: from [10.250.100.73] (ileax41-snat.itg.ti.com [10.172.224.153]) by fllv0040.itg.ti.com (8.15.2/8.15.2) with ESMTP id 10FJZUTY024413; Fri, 15 Jan 2021 13:35:33 -0600 Subject: Re: [PATCH v4 net-next 01/11] net: switchdev: remove vid_begin -> vid_end range from VLAN objects To: Vladimir Oltean , "David S. Miller" , Jakub Kicinski , CC: Florian Fainelli , Andrew Lunn , Vivien Didelot , Kurt Kanzenbach , Hauke Mehrtens , Woojung Huh , Microchip Linux Driver Support , Sean Wang , Landen Chao , Claudiu Manoil , Alexandre Belloni , Linus Walleij , Vadym Kochan , Taras Chornyi , Jiri Pirko , Ido Schimmel , Ioana Ciornei , Ivan Vecera , Petr Machata References: <20210109000156.1246735-1-olteanv@gmail.com> <20210109000156.1246735-2-olteanv@gmail.com> From: Grygorii Strashko Message-ID: <75bd8b0d-d765-20f3-e407-28c2ef4ac52e@ti.com> Date: Fri, 15 Jan 2021 21:35:30 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210109000156.1246735-2-olteanv@gmail.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 09/01/2021 02:01, Vladimir Oltean wrote: > From: Vladimir Oltean > > The call path of a switchdev VLAN addition to the bridge looks something > like this today: > > nbp_vlan_init > | __br_vlan_set_default_pvid > | | | > | | br_afspec | > | | | | > | | v | > | | br_process_vlan_info | > | | | | > | | v | > | | br_vlan_info | > | | / \ / > | | / \ / > | | / \ / > | | / \ / > v v v v v > nbp_vlan_add br_vlan_add ------+ > | ^ ^ | | > | / | | | > | / / / | > \ br_vlan_get_master/ / v > \ ^ / / br_vlan_add_existing > \ | / / | > \ | / / / > \ | / / / > \ | / / / > \ | / / / > v | | v / > __vlan_add / > / | / > / | / > v | / > __vlan_vid_add | / > \ | / > v v v > br_switchdev_port_vlan_add > > The ranges UAPI was introduced to the bridge in commit bdced7ef7838 > ("bridge: support for multiple vlans and vlan ranges in setlink and > dellink requests") (Jan 10 2015). But the VLAN ranges (parsed in br_afspec) > have always been passed one by one, through struct bridge_vlan_info > tmp_vinfo, to br_vlan_info. So the range never went too far in depth. > > Then Scott Feldman introduced the switchdev_port_bridge_setlink function > in commit 47f8328bb1a4 ("switchdev: add new switchdev bridge setlink"). > That marked the introduction of the SWITCHDEV_OBJ_PORT_VLAN, which made > full use of the range. But switchdev_port_bridge_setlink was called like > this: > > br_setlink > -> br_afspec > -> switchdev_port_bridge_setlink > > Basically, the switchdev and the bridge code were not tightly integrated. > Then commit 41c498b9359e ("bridge: restore br_setlink back to original") > came, and switchdev drivers were required to implement > .ndo_bridge_setlink = switchdev_port_bridge_setlink for a while. > > In the meantime, commits such as 0944d6b5a2fa ("bridge: try switchdev op > first in __vlan_vid_add/del") finally made switchdev penetrate the > br_vlan_info() barrier and start to develop the call path we have today. > But remember, br_vlan_info() still receives VLANs one by one. > > Then Arkadi Sharshevsky refactored the switchdev API in 2017 in commit > 29ab586c3d83 ("net: switchdev: Remove bridge bypass support from > switchdev") so that drivers would not implement .ndo_bridge_setlink any > longer. The switchdev_port_bridge_setlink also got deleted. > This refactoring removed the parallel bridge_setlink implementation from > switchdev, and left the only switchdev VLAN objects to be the ones > offloaded from __vlan_vid_add (basically RX filtering) and __vlan_add > (the latter coming from commit 9c86ce2c1ae3 ("net: bridge: Notify about > bridge VLANs")). > > That is to say, today the switchdev VLAN object ranges are not used in > the kernel. Refactoring the above call path is a bit complicated, when > the bridge VLAN call path is already a bit complicated. > > Let's go off and finish the job of commit 29ab586c3d83 by deleting the > bogus iteration through the VLAN ranges from the drivers. Some aspects > of this feature never made too much sense in the first place. For > example, what is a range of VLANs all having the BRIDGE_VLAN_INFO_PVID > flag supposed to mean, when a port can obviously have a single pvid? > This particular configuration _is_ denied as of commit 6623c60dc28e > ("bridge: vlan: enforce no pvid flag in vlan ranges"), but from an API > perspective, the driver still has to play pretend, and only offload the > vlan->vid_end as pvid. And the addition of a switchdev VLAN object can > modify the flags of another, completely unrelated, switchdev VLAN > object! (a VLAN that is PVID will invalidate the PVID flag from whatever > other VLAN had previously been offloaded with switchdev and had that > flag. Yet switchdev never notifies about that change, drivers are > supposed to guess). > > Nonetheless, having a VLAN range in the API makes error handling look > scarier than it really is - unwinding on errors and all of that. > When in reality, no one really calls this API with more than one VLAN. > It is all unnecessary complexity. > > And despite appearing pretentious (two-phase transactional model and > all), the switchdev API is really sloppy because the VLAN addition and > removal operations are not paired with one another (you can add a VLAN > 100 times and delete it just once). The bridge notifies through > switchdev of a VLAN addition not only when the flags of an existing VLAN > change, but also when nothing changes. There are switchdev drivers out > there who don't like adding a VLAN that has already been added, and > those checks don't really belong at driver level. But the fact that the > API contains ranges is yet another factor that prevents this from being > addressed in the future. > > Of the existing switchdev pieces of hardware, it appears that only > Mellanox Spectrum supports offloading more than one VLAN at a time, > through mlxsw_sp_port_vlan_set. I have kept that code internal to the > driver, because there is some more bookkeeping that makes use of it, but > I deleted it from the switchdev API. But since the switchdev support for > ranges has already been de facto deleted by a Mellanox employee and > nobody noticed for 4 years, I'm going to assume it's not a biggie. > > Signed-off-by: Vladimir Oltean > Reviewed-by: Ido Schimmel # switchdev and mlxsw Reviewed-by: Grygorii Strashko # cpsw_switchdev -- Best regards, grygorii