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=-6.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 8C748C433DF for ; Wed, 29 Jul 2020 12:24:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 65359206D8 for ; Wed, 29 Jul 2020 12:24:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="fjWLYLgV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726710AbgG2MYN (ORCPT ); Wed, 29 Jul 2020 08:24:13 -0400 Received: from fllv0016.ext.ti.com ([198.47.19.142]:60428 "EHLO fllv0016.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726476AbgG2MYK (ORCPT ); Wed, 29 Jul 2020 08:24:10 -0400 Received: from lelv0266.itg.ti.com ([10.180.67.225]) by fllv0016.ext.ti.com (8.15.2/8.15.2) with ESMTP id 06TCNX8e074308; Wed, 29 Jul 2020 07:23:33 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1596025413; bh=BO7ozKlRvMxchUxIZF8YK9YBjHx6pd/2cLcNf8dQg1Q=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=fjWLYLgVh/n6t7svV2jwlWZPIKgfYMd2fdomoKLxY+wghe8XoytW4D6w7Y0JinZ2P TyJku+p2lmkUMMPOJhi7yVN3J1wdJBTZ2oPD7K7WDvLT9rCM9eoH46B+pOMw6sdhNA XqaoM0iBW8t+Mm/5KhEeS0N3gXbcHOXqDCJhvOmo= Received: from DLEE111.ent.ti.com (dlee111.ent.ti.com [157.170.170.22]) by lelv0266.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 06TCNXRG007341 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 29 Jul 2020 07:23:33 -0500 Received: from DLEE108.ent.ti.com (157.170.170.38) by DLEE111.ent.ti.com (157.170.170.22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1979.3; Wed, 29 Jul 2020 07:23:32 -0500 Received: from fllv0039.itg.ti.com (10.64.41.19) by DLEE108.ent.ti.com (157.170.170.38) 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; Wed, 29 Jul 2020 07:23:32 -0500 Received: from [10.250.100.73] (ileax41-snat.itg.ti.com [10.172.224.153]) by fllv0039.itg.ti.com (8.15.2/8.15.2) with ESMTP id 06TCNSZA088346; Wed, 29 Jul 2020 07:23:29 -0500 Subject: Re: [PATCH v2 4/9] mlxsw: spectrum_ptp: Use generic helper function To: Petr Machata , Kurt Kanzenbach CC: Richard Cochran , Andrew Lunn , Vivien Didelot , Florian Fainelli , "David S. Miller" , Jakub Kicinski , Jiri Pirko , Ido Schimmel , Heiner Kallweit , Russell King , Ivan Khoronzhuk , Samuel Zou , References: <20200727090601.6500-1-kurt@linutronix.de> <20200727090601.6500-5-kurt@linutronix.de> <87a6zli04l.fsf@mellanox.com> <875za7sr7b.fsf@kurt> <87pn8fgxj3.fsf@mellanox.com> From: Grygorii Strashko Message-ID: <855a0345-62c9-17b0-54fb-e74b1ef9b8b9@ti.com> Date: Wed, 29 Jul 2020 15:23:27 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <87pn8fgxj3.fsf@mellanox.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 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 29/07/2020 00:06, Petr Machata wrote: > > Kurt Kanzenbach writes: > >> On Mon Jul 27 2020, Petr Machata wrote: >>> So this looks good, and works, but I'm wondering about one thing. >> >> Thanks for testing. >> >>> >>> Your code (and evidently most drivers as well) use a different check >>> than mlxsw, namely skb->len + ETH_HLEN < X. When I print_hex_dump() >>> skb_mac_header(skb), skb->len in mlxsw with some test packet, I get e.g. >>> this: >>> >>> 00000000259a4db7: 01 00 5e 00 01 81 00 02 c9 a4 e4 e1 08 00 45 00 ..^...........E. >>> 000000005f29f0eb: 00 48 0d c9 40 00 01 11 c8 59 c0 00 02 01 e0 00 .H..@....Y...... >>> 00000000f3663e9e: 01 81 01 3f 01 3f 00 34 9f d3 00 02 00 2c 00 00 ...?.?.4.....,.. >>> ^sp^^ ^dp^^ ^len^ ^cks^ ^len^ >>> 00000000b3914606: 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 02 ................ >>> 000000002e7828ea: c9 ff fe a4 e4 e1 00 01 09 fa 00 00 00 00 00 00 ................ >>> 000000000b98156e: 00 00 00 00 00 00 ...... >>> >>> Both UDP and PTP length fields indicate that the payload ends exactly at >>> the end of the dump. So apparently skb->len contains all the payload >>> bytes, including the Ethernet header. >>> >>> Is that the case for other drivers as well? Maybe mlxsw is just missing >>> some SKB magic in the driver. >> >> So I run some tests (on other hardware/drivers) and it seems like that >> the skb->len usually doesn't include the ETH_HLEN. Therefore, it is >> added to the check. >> >> Looking at the driver code: >> >> |static void mlxsw_sp_rx_sample_listener(struct sk_buff *skb, u8 local_port, >> | void *trap_ctx) >> |{ >> | [...] >> | /* The sample handler expects skb->data to point to the start of the >> | * Ethernet header. >> | */ >> | skb_push(skb, ETH_HLEN); >> | mlxsw_sp_sample_receive(mlxsw_sp, skb, local_port); >> |} >> >> Maybe that's the issue here? > > Correct, mlxsw pushes the header very soon. Given that both > ptp_classify_raw() and eth_type_trans() that are invoked later assume > the header, it is reasonable. I have shuffled the pushes around and have > a patch that both works and I think is correct. > > However, I find it odd that ptp_classify_raw() assumes that ->data > points at Ethernet, while ptp_parse_header() makes the contrary > assumption that ->len does not cover Ethernet. Those functions are > likely to be used just a couple calls away from each other, if not > outright next to each other. > > I suspect that ti/cpts.c and ti/am65-cpts.c (patches 5 and 6) actually > hit an issue in this. ptp_classify_raw() is called without a surrounding > _push / _pull (unlike DSA), which would imply skb->data points at > Ethernet header, and indeed, the way the "data" variable is used > confirms it. Both drivers, in all cases, will get ->data points at Ethernet header and ->len covers ETH_HLEN So, yes below check is incorrect, in general, and will be false always if other calculation are correct (only IPV4_HLEN(data + offset) can cause issues). if (skb->len + ETH_HLEN < offset + OFF_PTP_SEQUENCE_ID + sizeof(*seqid)) return 0; it might be good to update ptp_parse_header() documentation with expected state of skb. (At the same time the code adds ETH_HLEN to skb->len, but > maybe it is just a cut'n'paste.) But then ptp_parse_header() is called, > and that makes the assumption that skb->len does not cover the Ethernet > header. > >> I was also wondering about something else in that driver driver: The >> parsing code allows for ptp v1, but the message type was always fetched >> from offset 0 in the header. Is that indented? > > Yeah, I noticed that as well. That was a bug in the mlxsw code. Good > riddance :) > -- Best regards, grygorii