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=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 155FBC282C2 for ; Thu, 7 Feb 2019 11:43:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D8CB121908 for ; Thu, 7 Feb 2019 11:43:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549539782; bh=7RNYN+uRtxRQ7agnUfIJ7uzbPpJGK5QJNVm2RN+mbe0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=hYFi+AdMShLTm10cdFTDMuyY1OG4wq7jzG0srOBdj/Ztq/XaXkOhaIzeE83TUa6Kk BqMznVx84xFEUZ05M8FeReuMbj62VcQuu8M6Q+k2DDeSa9ezOtcm0/jPy34EGgsG+J BQFmDTUAH3YN8aw5+ZinJizeTB13A1XG6ZgHkyzs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727279AbfBGLnB (ORCPT ); Thu, 7 Feb 2019 06:43:01 -0500 Received: from mail.kernel.org ([198.145.29.99]:33090 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727249AbfBGLm7 (ORCPT ); Thu, 7 Feb 2019 06:42:59 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C424721904; Thu, 7 Feb 2019 11:42:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549539778; bh=7RNYN+uRtxRQ7agnUfIJ7uzbPpJGK5QJNVm2RN+mbe0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=y4dCLTtkMQALaWDpCiqdDcfbLrobVEW5Pg0l3fKbWXMBOHraIltM8KyzA3N3aXjkr X1XmTmoycD1eiuFf6Ss7ZbkS3xxuQ9win+qqdKaBb3tfnQ6DgVmWzK3sGZ13lJnnxL jdyTBnmShtOe7XFsK4Pkog3de5y6kK0ggr79cWbk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , "David S. Miller" , Ben Hutchings Subject: [PATCH 4.4 20/34] inet: frags: get rid of ipfrag_skb_cb/FRAG_CB Date: Thu, 7 Feb 2019 12:42:02 +0100 Message-Id: <20190207113026.358197610@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190207113025.552605181@linuxfoundation.org> References: <20190207113025.552605181@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet commit bf66337140c64c27fa37222b7abca7e49d63fb57 upstream. ip_defrag uses skb->cb[] to store the fragment offset, and unfortunately this integer is currently in a different cache line than skb->next, meaning that we use two cache lines per skb when finding the insertion point. By aliasing skb->ip_defrag_offset and skb->dev, we pack all the fields in a single cache line and save precious memory bandwidth. Note that after the fast path added by Changli Gao in commit d6bebca92c66 ("fragment: add fast path for in-order fragments") this change wont help the fast path, since we still need to access prev->len (2nd cache line), but will show great benefits when slow path is entered, since we perform a linear scan of a potentially long list. Also, note that this potential long list is an attack vector, we might consider also using an rb-tree there eventually. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- include/linux/skbuff.h | 5 +++++ 1 file changed, 5 insertions(+) --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -558,6 +558,11 @@ struct sk_buff { }; struct rb_node rbnode; /* used in netem & tcp stack */ }; + + union { + int ip_defrag_offset; + }; + struct sock *sk; struct net_device *dev;