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=-3.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 726DDC43603 for ; Fri, 6 Dec 2019 15:06:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3980B24659 for ; Fri, 6 Dec 2019 15:06:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=dlink.ru header.i=@dlink.ru header.b="lHbMNkR+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726480AbfLFPG1 (ORCPT ); Fri, 6 Dec 2019 10:06:27 -0500 Received: from fd.dlink.ru ([178.170.168.18]:43908 "EHLO fd.dlink.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726244AbfLFPG0 (ORCPT ); Fri, 6 Dec 2019 10:06:26 -0500 Received: by fd.dlink.ru (Postfix, from userid 5000) id 46DE61B214D6; Fri, 6 Dec 2019 18:06:22 +0300 (MSK) DKIM-Filter: OpenDKIM Filter v2.11.0 fd.dlink.ru 46DE61B214D6 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dlink.ru; s=mail; t=1575644783; bh=TNURWtYg5VbgmOVt3Zu3a5GrkMmxUJgdKkf+0OlgfLQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=lHbMNkR+fWnv0r2T339Yr8QNbkjw+56435jESnAW0VZswNTpRQnSVj+ZlsqIe6Qd2 HFxFiBh+Odu+eYudoZNs+eXtT3GqmfNsm5+yv+vgUEx//zGosjtjUPM2YGryvMuBxR bXMODReAz4v6JrvN0JHsgxpD9ugyYCAPg4RyeQGQ= Received: from mail.rzn.dlink.ru (mail.rzn.dlink.ru [178.170.168.13]) by fd.dlink.ru (Postfix) with ESMTP id 00AD41B21308; Fri, 6 Dec 2019 18:06:09 +0300 (MSK) DKIM-Filter: OpenDKIM Filter v2.11.0 fd.dlink.ru 00AD41B21308 Received: from mail.rzn.dlink.ru (localhost [127.0.0.1]) by mail.rzn.dlink.ru (Postfix) with ESMTP id 8D5981B20228; Fri, 6 Dec 2019 18:06:09 +0300 (MSK) Received: from mail.rzn.dlink.ru (localhost [127.0.0.1]) by mail.rzn.dlink.ru (Postfix) with ESMTPA; Fri, 6 Dec 2019 18:06:09 +0300 (MSK) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Date: Fri, 06 Dec 2019 18:06:09 +0300 From: Alexander Lobakin To: "David S. Miller" Cc: Florian Fainelli , Muciri Gatimu , Shashidhar Lakkavalli , John Crispin , Andrew Lunn , Vivien Didelot , Stanislav Fomichev , Daniel Borkmann , Song Liu , Alexei Starovoitov , Matteo Croce , Jakub Sitnicki , Eric Dumazet , Paul Blakey , Yoshiki Komachi , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net] net: dsa: fix flow dissection on Tx path In-Reply-To: <5d3d0907-4f99-ccda-82f4-12e514c5edb2@gmail.com> References: <20191205100235.14195-1-alobakin@dlink.ru> <5d3d0907-4f99-ccda-82f4-12e514c5edb2@gmail.com> User-Agent: Roundcube Webmail/1.4.0 Message-ID: <71305dd0f15bd065f9b1eedd4f61123e@dlink.ru> X-Sender: alobakin@dlink.ru Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Florian Fainelli wrote 06.12.2019 06:28: > On 12/5/2019 2:02 AM, Alexander Lobakin wrote: >> Commit 43e665287f93 ("net-next: dsa: fix flow dissection") added an >> ability to override protocol and network offset during flow dissection >> for DSA-enabled devices (i.e. controllers shipped as switch CPU ports) >> in order to fix skb hashing for RPS on Rx path. >> >> However, skb_hash() and added part of code can be invoked not only on >> Rx, but also on Tx path if we have a multi-queued device and: >> - kernel is running on UP system or >> - XPS is not configured. >> >> The call stack in this two cases will be like: dev_queue_xmit() -> >> __dev_queue_xmit() -> netdev_core_pick_tx() -> netdev_pick_tx() -> >> skb_tx_hash() -> skb_get_hash(). >> >> The problem is that skbs queued for Tx have both network offset and >> correct protocol already set up even after inserting a CPU tag by DSA >> tagger, so calling tag_ops->flow_dissect() on this path actually only >> breaks flow dissection and hashing. >> >> This can be observed by adding debug prints just before and right >> after >> tag_ops->flow_dissect() call to the related block of code: >> >> Before the patch: >> >> Rx path (RPS): >> >> [ 19.240001] Rx: proto: 0x00f8, nhoff: 0 /* ETH_P_XDSA */ >> [ 19.244271] tag_ops->flow_dissect() >> [ 19.247811] Rx: proto: 0x0800, nhoff: 8 /* ETH_P_IP */ >> >> [ 19.215435] Rx: proto: 0x00f8, nhoff: 0 /* ETH_P_XDSA */ >> [ 19.219746] tag_ops->flow_dissect() >> [ 19.223241] Rx: proto: 0x0806, nhoff: 8 /* ETH_P_ARP */ >> >> [ 18.654057] Rx: proto: 0x00f8, nhoff: 0 /* ETH_P_XDSA */ >> [ 18.658332] tag_ops->flow_dissect() >> [ 18.661826] Rx: proto: 0x8100, nhoff: 8 /* ETH_P_8021Q */ >> >> Tx path (UP system): >> >> [ 18.759560] Tx: proto: 0x0800, nhoff: 26 /* ETH_P_IP */ >> [ 18.763933] tag_ops->flow_dissect() >> [ 18.767485] Tx: proto: 0x920b, nhoff: 34 /* junk */ >> >> [ 22.800020] Tx: proto: 0x0806, nhoff: 26 /* ETH_P_ARP */ >> [ 22.804392] tag_ops->flow_dissect() >> [ 22.807921] Tx: proto: 0x920b, nhoff: 34 /* junk */ >> >> [ 16.898342] Tx: proto: 0x86dd, nhoff: 26 /* ETH_P_IPV6 */ >> [ 16.902705] tag_ops->flow_dissect() >> [ 16.906227] Tx: proto: 0x920b, nhoff: 34 /* junk */ >> >> After: >> >> Rx path (RPS): >> >> [ 16.520993] Rx: proto: 0x00f8, nhoff: 0 /* ETH_P_XDSA */ >> [ 16.525260] tag_ops->flow_dissect() >> [ 16.528808] Rx: proto: 0x0800, nhoff: 8 /* ETH_P_IP */ >> >> [ 15.484807] Rx: proto: 0x00f8, nhoff: 0 /* ETH_P_XDSA */ >> [ 15.490417] tag_ops->flow_dissect() >> [ 15.495223] Rx: proto: 0x0806, nhoff: 8 /* ETH_P_ARP */ >> >> [ 17.134621] Rx: proto: 0x00f8, nhoff: 0 /* ETH_P_XDSA */ >> [ 17.138895] tag_ops->flow_dissect() >> [ 17.142388] Rx: proto: 0x8100, nhoff: 8 /* ETH_P_8021Q */ >> >> Tx path (UP system): >> >> [ 15.499558] Tx: proto: 0x0800, nhoff: 26 /* ETH_P_IP */ >> >> [ 20.664689] Tx: proto: 0x0806, nhoff: 26 /* ETH_P_ARP */ >> >> [ 18.565782] Tx: proto: 0x86dd, nhoff: 26 /* ETH_P_IPV6 */ >> >> In order to fix that we can add the check 'proto == htons(ETH_P_XDSA)' >> to prevent code from calling tag_ops->flow_dissect() on Tx. >> I also decided to initialize 'offset' variable so tagger callbacks can >> now safely leave it untouched without provoking a chaos. >> >> Fixes: 43e665287f93 ("net-next: dsa: fix flow dissection") >> Signed-off-by: Alexander Lobakin > > Reviewed-by: Florian Fainelli So Dave, you can pick it up into your fixes tree if I understand correctly. There will be further work on DSA Rx path, but it's a subject for next Linux release cycles essentially. Regards, ᚷ ᛖ ᚢ ᚦ ᚠ ᚱ