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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 80E12C43215 for ; Fri, 15 Nov 2019 07:36:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5A2982073B for ; Fri, 15 Nov 2019 07:36:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=dlink.ru header.i=@dlink.ru header.b="SfuWrd47" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727065AbfKOHgZ (ORCPT ); Fri, 15 Nov 2019 02:36:25 -0500 Received: from fd.dlink.ru ([178.170.168.18]:45614 "EHLO fd.dlink.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725829AbfKOHgZ (ORCPT ); Fri, 15 Nov 2019 02:36:25 -0500 Received: by fd.dlink.ru (Postfix, from userid 5000) id 5F79F1B21219; Fri, 15 Nov 2019 10:36:19 +0300 (MSK) DKIM-Filter: OpenDKIM Filter v2.11.0 fd.dlink.ru 5F79F1B21219 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dlink.ru; s=mail; t=1573803379; bh=auYJSdX39uan+gvUCsaNo2NaaQLgfRyrUszL7DhJUb4=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=SfuWrd47XdQioLUmZkIhQ3OMs+HeaDWSatiVwQEdzY6ZWJg2pT1l1h5EpRzPJOv1V iwF6IOh6Wr3/0/ynRcejg8zch7KZVc5GEmUbQMUJVgrUDcjeky25QHC4/jtsEcdxeX QQyOIe6XZqOm2o6R0+fxyLS063xmDUIB+DB8uGYo= Received: from mail.rzn.dlink.ru (mail.rzn.dlink.ru [178.170.168.13]) by fd.dlink.ru (Postfix) with ESMTP id D61961B203C6; Fri, 15 Nov 2019 10:36:08 +0300 (MSK) DKIM-Filter: OpenDKIM Filter v2.11.0 fd.dlink.ru D61961B203C6 Received: from mail.rzn.dlink.ru (localhost [127.0.0.1]) by mail.rzn.dlink.ru (Postfix) with ESMTP id 9C6611B21209; Fri, 15 Nov 2019 10:36:08 +0300 (MSK) Received: from mail.rzn.dlink.ru (localhost [127.0.0.1]) by mail.rzn.dlink.ru (Postfix) with ESMTPA; Fri, 15 Nov 2019 10:36:08 +0300 (MSK) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Date: Fri, 15 Nov 2019 10:36:08 +0300 From: Alexander Lobakin To: David Miller Cc: ecree@solarflare.com, jiri@mellanox.com, edumazet@google.com, idosch@mellanox.com, pabeni@redhat.com, petrm@mellanox.com, sd@queasysnail.net, f.fainelli@gmail.com, jaswinder.singh@linaro.org, manishc@marvell.com, GR-Linux-NIC-Dev@marvell.com, johannes.berg@intel.com, emmanuel.grumbach@intel.com, luciano.coelho@intel.com, linuxwifi@intel.com, kvalo@codeaurora.org, netdev@vger.kernel.org, linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next] net: core: allow fast GRO for skbs with Ethernet header in head In-Reply-To: <20191114.172508.1027995193093100862.davem@davemloft.net> References: <20191112122843.30636-1-alobakin@dlink.ru> <20191114.172508.1027995193093100862.davem@davemloft.net> User-Agent: Roundcube Webmail/1.4.0 Message-ID: <097eb720466a7c429c8fd91c792e7cd5@dlink.ru> X-Sender: alobakin@dlink.ru Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi Dave, David Miller wrote 15.11.2019 04:25: > From: Alexander Lobakin > Date: Tue, 12 Nov 2019 15:28:43 +0300 > >> Commit 78d3fd0b7de8 ("gro: Only use skb_gro_header for completely >> non-linear packets") back in May'09 (2.6.31-rc1) has changed the >> original condition '!skb_headlen(skb)' to the current >> 'skb_mac_header(skb) == skb_tail_pointer(skb)' in gro_reset_offset() >> saying: "Since the drivers that need this optimisation all provide >> completely non-linear packets". > > Please reference the appropriate SHA1-ID both here in this paragraph > and > also in an appropriate Fixes: tag. Sorry for confusing. The SHA1-ID from commit message is correct actually. At the moment of 2.6.31 we used skb->mac_header and skb->tail pointers directly, so the original condition was 'skb->mac_header == skb->tail'. Commit ced14f6804a9 ("net: Correct comparisons and calculations using skb->tail and skb-transport_header") has changed this condition to the referred 'skb_mac_header(skb) == skb_tail_pointer(skb)' without any functional changes. I didn't add the "Fixes:" tag because at the moment of 2.6.31 it was a needed change, but it became obsolete later, so now we can revert it back to speed up skbs with only Ethernet header in head. Please let me know if I must send v2 of this patch with corrected description before getting any further reviews. Thanks. > If this goes so far back that it is before GIT, then you need to > provide > a reference to the patch posting via lore.kernel.org or similar because > it is absolutely essentialy for people reviewing this patch to be able > to do some digging into why the condition is code the way that it is > currently. > > Thank you. Regards, ᚷ ᛖ ᚢ ᚦ ᚠ ᚱ