From patchwork Sun Nov 14 21:35:27 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jesper Juhl X-Patchwork-Id: 71155 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 A54EFB7112 for ; Mon, 15 Nov 2010 08:48:09 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932333Ab0KNVrl (ORCPT ); Sun, 14 Nov 2010 16:47:41 -0500 Received: from swampdragon.chaosbits.net ([90.184.90.115]:26691 "EHLO swampdragon.chaosbits.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932243Ab0KNVrj (ORCPT ); Sun, 14 Nov 2010 16:47:39 -0500 Received: by swampdragon.chaosbits.net (Postfix, from userid 1000) id B27659403D; Sun, 14 Nov 2010 22:35:27 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by swampdragon.chaosbits.net (Postfix) with ESMTP id AB3769403B; Sun, 14 Nov 2010 22:35:27 +0100 (CET) Date: Sun, 14 Nov 2010 22:35:27 +0100 (CET) From: Jesper Juhl To: Netfilter Core Team cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, netfilter@vger.kernel.org, netfilter-devel@vger.kernel.org, "David S. Miller" , Rusty Russell Subject: [PATCH] Reduce number of pointer dereferences in IPv4 netfilter LOG module function dump_packet() Message-ID: User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org By adding two pointer variables to net/ipv4/netfilter/ipt_LOG.c::dump_packet() we can save 16 bytes of .text and 9 pointer dereferences. before this patch we did 20 pointer dereferences and had this object file size: text data bss dec hex filename 6233 600 3080 9913 26b9 net/ipv4/netfilter/ipt_LOG.o after this patch we do just 11 pointer dereferences and have this object file size: text data bss dec hex filename 6217 600 3080 9897 26a9 net/ipv4/netfilter/ipt_LOG.o Please Cc me on replies. Signed-off-by: Jesper Juhl --- ipt_LOG.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/net/ipv4/netfilter/ipt_LOG.c b/net/ipv4/netfilter/ipt_LOG.c index 72ffc8f..02a92de 100644 --- a/net/ipv4/netfilter/ipt_LOG.c +++ b/net/ipv4/netfilter/ipt_LOG.c @@ -39,6 +39,8 @@ static void dump_packet(struct sbuff *m, struct iphdr _iph; const struct iphdr *ih; unsigned int logflags; + struct sock *sk; + struct socket *sk_socket; if (info->type == NF_LOG_TYPE_LOG) logflags = info->u.log.logflags; @@ -335,13 +337,15 @@ static void dump_packet(struct sbuff *m, } /* Max length: 15 "UID=4294967295 " */ - if ((logflags & IPT_LOG_UID) && !iphoff && skb->sk) { - read_lock_bh(&skb->sk->sk_callback_lock); - if (skb->sk->sk_socket && skb->sk->sk_socket->file) + sk = skb->sk; + sk_socket = sk->sk_socket; + if ((logflags & IPT_LOG_UID) && !iphoff && sk) { + read_lock_bh(&sk->sk_callback_lock); + if (sk_socket && 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_socket->file->f_cred->fsuid, + sk_socket->file->f_cred->fsgid); + read_unlock_bh(&sk->sk_callback_lock); } /* Max length: 16 "MARK=0xFFFFFFFF " */