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=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 AF843C43603 for ; Thu, 5 Dec 2019 10:03:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 46CD724652 for ; Thu, 5 Dec 2019 10:03:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=dlink.ru header.i=@dlink.ru header.b="HNhL63xC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729220AbfLEKDs (ORCPT ); Thu, 5 Dec 2019 05:03:48 -0500 Received: from fd.dlink.ru ([178.170.168.18]:38436 "EHLO fd.dlink.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726239AbfLEKDr (ORCPT ); Thu, 5 Dec 2019 05:03:47 -0500 Received: by fd.dlink.ru (Postfix, from userid 5000) id 0DCFD1B214D6; Thu, 5 Dec 2019 13:03:43 +0300 (MSK) DKIM-Filter: OpenDKIM Filter v2.11.0 fd.dlink.ru 0DCFD1B214D6 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dlink.ru; s=mail; t=1575540224; bh=yI7KF/bM4Qa4hyw06HNlRSt7/ikY+NEJAJCnnl7lFyY=; h=From:To:Cc:Subject:Date; b=HNhL63xCyq243WuhJA1bkWHqxknokV8KgpHTlCqpuj+wcYHSLqeU/yApJ6+XKsdAO Wycy6lRs3et8dSpMHkLzzruDRj6O6CsfGMyJzfniIROvtEgCllYi+CmUFks1JsqRvs TwpwZnQ4knnIjGAmVmZDBk8T5lpZlvWDle7S0jkw= Received: from mail.rzn.dlink.ru (mail.rzn.dlink.ru [178.170.168.13]) by fd.dlink.ru (Postfix) with ESMTP id 403331B20144; Thu, 5 Dec 2019 13:03:26 +0300 (MSK) DKIM-Filter: OpenDKIM Filter v2.11.0 fd.dlink.ru 403331B20144 Received: from mail.rzn.dlink.ru (localhost [127.0.0.1]) by mail.rzn.dlink.ru (Postfix) with ESMTP id 005F01B219AA; Thu, 5 Dec 2019 13:03:24 +0300 (MSK) Received: from localhost.localdomain (unknown [196.196.203.126]) by mail.rzn.dlink.ru (Postfix) with ESMTPA; Thu, 5 Dec 2019 13:03:24 +0300 (MSK) From: Alexander Lobakin To: "David S. Miller" Cc: Muciri Gatimu , Shashidhar Lakkavalli , John Crispin , Andrew Lunn , Vivien Didelot , Florian Fainelli , Stanislav Fomichev , Daniel Borkmann , Song Liu , Alexei Starovoitov , Matteo Croce , Jakub Sitnicki , Eric Dumazet , Paul Blakey , Yoshiki Komachi , Alexander Lobakin , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH net] net: dsa: fix flow dissection on Tx path Date: Thu, 5 Dec 2019 13:02:35 +0300 Message-Id: <20191205100235.14195-1-alobakin@dlink.ru> X-Mailer: git-send-email 2.24.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- net/core/flow_dissector.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index 69395b804709..d524a693e00f 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -969,9 +969,10 @@ bool __skb_flow_dissect(const struct net *net, nhoff = skb_network_offset(skb); hlen = skb_headlen(skb); #if IS_ENABLED(CONFIG_NET_DSA) - if (unlikely(skb->dev && netdev_uses_dsa(skb->dev))) { + if (unlikely(skb->dev && netdev_uses_dsa(skb->dev) && + proto == htons(ETH_P_XDSA))) { const struct dsa_device_ops *ops; - int offset; + int offset = 0; ops = skb->dev->dsa_ptr->tag_ops; if (ops->flow_dissect && -- 2.24.0