From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-1?Q?Timo_Ter=E4s?= Subject: Re: [PATCH] [IPV4]: Update MTU to all related cache entries in ip_rt_frag_needed() Date: Sun, 27 Apr 2008 11:35:42 +0300 Message-ID: <48143ADE.40304@iki.fi> References: <48105B67.7060804@iki.fi> <20080426.232756.259679168.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev@vger.kernel.org To: David Miller Return-path: Received: from nf-out-0910.google.com ([64.233.182.185]:43893 "EHLO nf-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752474AbYD0IfQ (ORCPT ); Sun, 27 Apr 2008 04:35:16 -0400 Received: by nf-out-0910.google.com with SMTP id g13so1699990nfb.21 for ; Sun, 27 Apr 2008 01:35:14 -0700 (PDT) In-Reply-To: <20080426.232756.259679168.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: David Miller wrote: > From: Timo_Ter=E4s > Date: Thu, 24 Apr 2008 13:05:27 +0300 >=20 >> Add struct net_device parameter to ip_rt_frag_needed() and update MT= U to >> cache entries where ifindex is specified. This is similar to what is >> already done in ip_rt_redirect(). >> >> Signed-off-by: Timo Teras >=20 > I haven't forgotten about this patch, I'm just still thinking about > possible negative side effects. I don't think there are any, but > I want to be sure. >=20 > This function has been a constant source of consternation. It also > doesn't do the right thing when the TOS is modified mid-network, and > that's arguably wrong too but more difficult to solve efficiently tha= n > this ifindex keying case. I understand your concern. It is pretty easy break routing cache with some seemingly unrelated changes. I tried to think about possible side effects, but concluded that this should be safe. Then again, I don't know all the tiny details and unusual scenarios. But I have been runnin= g a 2.6.23 kernel with (backported) patch on a production machine (router connected to two ISPs, internal subnet and also having multiple gre tunnels), so far I have not encountered any problems. Cheers, Timo