From patchwork Mon Nov 15 21:49:01 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Jesper Juhl X-Patchwork-Id: 71309 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 25A56B712A for ; Tue, 16 Nov 2010 09:01:53 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933719Ab0KOWBW (ORCPT ); Mon, 15 Nov 2010 17:01:22 -0500 Received: from swampdragon.chaosbits.net ([90.184.90.115]:22498 "EHLO swampdragon.chaosbits.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758568Ab0KOWBV (ORCPT ); Mon, 15 Nov 2010 17:01:21 -0500 Received: by swampdragon.chaosbits.net (Postfix, from userid 1000) id 781039403D; Mon, 15 Nov 2010 22:49:01 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by swampdragon.chaosbits.net (Postfix) with ESMTP id 755759403B; Mon, 15 Nov 2010 22:49:01 +0100 (CET) Date: Mon, 15 Nov 2010 22:49:01 +0100 (CET) From: Jesper Juhl To: Eric Dumazet cc: Netfilter Core Team , Jan Rekorajski , "David S. Miller" , netfilter-devel@vger.kernel.org, netfilter@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Reduce number of pointer dereferences in IPv6 netfilter LOG module function dump_packet() In-Reply-To: <1289782215.2743.167.camel@edumazet-laptop> Message-ID: References: <1289782215.2743.167.camel@edumazet-laptop> User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) MIME-Version: 1.0 Content-ID: Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, 15 Nov 2010, Eric Dumazet wrote: > Le dimanche 14 novembre 2010 à 22:47 +0100, Jesper Juhl a écrit : > > By adding two pointer variables to > > net/ipv6/netfilter/ip6t_LOG.c::dump_packet() we can save 19 bytes of .text > > and many pointer dereferences. > > > > before: > > text data bss dec hex filename > > 6258 600 3088 9946 26da net/ipv6/netfilter/ip6t_LOG.o > > > > after: > > text data bss dec hex filename > > 6239 600 3088 9927 26c7 net/ipv6/netfilter/ip6t_LOG.o > > > > > > Please Cc me on replies. > > > > > > Signed-off-by: Jesper Juhl > > --- > > ip6t_LOG.c | 16 ++++++++++------ > > 1 file changed, 10 insertions(+), 6 deletions(-) > > > > diff --git a/net/ipv6/netfilter/ip6t_LOG.c b/net/ipv6/netfilter/ip6t_LOG.c > > index 09c8889..51d10a5 100644 > > --- a/net/ipv6/netfilter/ip6t_LOG.c > > +++ b/net/ipv6/netfilter/ip6t_LOG.c [...] > > Same comment than previous patch, you add a NULL dereference. > Hopefully this is beter (same as change done to the other (ipv4) patch). Fewer pointer derefs and smaller .text size for net/ipv4/netfilter/ipt_LOG.c::dump_packet() Signed-off-by: Jesper Juhl --- ip6t_LOG.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/net/ipv6/netfilter/ip6t_LOG.c b/net/ipv6/netfilter/ip6t_LOG.c index 09c8889..de15b14 100644 --- a/net/ipv6/netfilter/ip6t_LOG.c +++ b/net/ipv6/netfilter/ip6t_LOG.c @@ -46,6 +46,7 @@ static void dump_packet(struct sbuff *m, unsigned int ptr; unsigned int hdrlen = 0; unsigned int logflags; + struct sock *sk; if (info->type == NF_LOG_TYPE_LOG) logflags = info->u.log.logflags; @@ -359,12 +360,13 @@ static void dump_packet(struct sbuff *m, /* Max length: 15 "UID=4294967295 " */ if ((logflags & IP6T_LOG_UID) && recurse && skb->sk) { - read_lock_bh(&skb->sk->sk_callback_lock); - if (skb->sk->sk_socket && skb->sk->sk_socket->file) + sk = skb->sk; + read_lock_bh(&sk->sk_callback_lock); + if (sk->sk_socket && sk->sk_socket->file) sb_add(m, "UID=%u GID=%u ", - skb->sk->sk_socket->file->f_cred->fsuid, - skb->sk->sk_socket->file->f_cred->fsgid); - read_unlock_bh(&skb->sk->sk_callback_lock); + sk->sk_socket->file->f_cred->fsuid, + sk->sk_socket->file->f_cred->fsgid); + read_unlock_bh(&sk->sk_callback_lock); } /* Max length: 16 "MARK=0xFFFFFFFF " */