From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [RFC] Question about potential problem in net/ipv4/route.c Date: Wed, 11 Oct 2006 23:02:33 -0700 (PDT) Message-ID: <20061011.230233.122062793.davem@davemloft.net> References: <200610111511.19028.dada1@cosmosbay.com> <20061011.220506.76273501.davem@davemloft.net> <452DD724.4030502@cosmosbay.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org Return-path: Received: from dsl027-180-168.sfo1.dsl.speakeasy.net ([216.27.180.168]:51347 "EHLO sunset.davemloft.net") by vger.kernel.org with ESMTP id S1161250AbWJLGCk (ORCPT ); Thu, 12 Oct 2006 02:02:40 -0400 To: dada1@cosmosbay.com In-Reply-To: <452DD724.4030502@cosmosbay.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Eric Dumazet Date: Thu, 12 Oct 2006 07:48:20 +0200 > Not on my gcc here (gcc version 3.4.4) : It wont zeros out the padding bytes Patrick just proved this too :) > Well, on this machine I have these oprofile numbers : > > : /* rt_intern_hash total: 993464 0.3619 */ > > 31751 0.0116 :ffffffff803e8d26: repz cmpsb %es:(%rdi),%ds:(%rsi) > 433438 0.1579 :ffffffff803e8d28: jne ffffffff803e8f80 Indeed, numbers talk bullshit walks :) How about something like this as a start? diff --git a/net/ipv4/route.c b/net/ipv4/route.c index c41ddba..4d4b1bd 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -566,9 +566,13 @@ static inline u32 rt_score(struct rtable static inline int compare_keys(struct flowi *fl1, struct flowi *fl2) { - return memcmp(&fl1->nl_u.ip4_u, &fl2->nl_u.ip4_u, sizeof(fl1->nl_u.ip4_u)) == 0 && - fl1->oif == fl2->oif && - fl1->iif == fl2->iif; + return ((fl1->nl_u.ip4_u.daddr ^ fl2->nl_u.ip4_u.daddr) | + (fl1->nl_u.ip4_u.saddr ^ fl2->nl_u.ip4_u.saddr) | + (fl1->nl_u.ip4_u.fwmark ^ fl2->nl_u.ip4_u.fwmark) | + (*(u16 *)&fl1->nl_u.ip4_u.tos ^ + *(u16 *)&fl2->nl_u.ip4_u.tos) | + (fl1->oif ^ fl2->oif) | + (fl1->iif ^ fl2->iif)) == 0; } #ifdef CONFIG_IP_ROUTE_MULTIPATH_CACHED