From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steffen Klassert Subject: Re: linux-3.0.x regression with ipv4 routes having mtu Date: Mon, 19 Dec 2011 14:52:59 +0100 Message-ID: <20111219135259.GK6348@secunet.com> References: <4EE8C6A8.3060308@iki.fi> <20111214.125010.82857701285437834.davem@davemloft.net> <20111215134957.GI6348@secunet.com> <20111216122147.GJ6348@secunet.com> <4EEB5602.2060806@iki.fi> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: David Miller , netdev@vger.kernel.org To: Timo =?iso-8859-1?Q?Ter=E4s?= Return-path: Received: from a.mx.secunet.com ([195.81.216.161]:58968 "EHLO a.mx.secunet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751997Ab1LSN5Y (ORCPT ); Mon, 19 Dec 2011 08:57:24 -0500 Content-Disposition: inline In-Reply-To: <4EEB5602.2060806@iki.fi> Sender: netdev-owner@vger.kernel.org List-ID: On Fri, Dec 16, 2011 at 04:30:26PM +0200, Timo Ter=E4s wrote: > On 12/16/2011 02:21 PM, Steffen Klassert wrote: > >=20 > > "ip route flush cache" does not even flush the routing cache, > > it just markes the routing cache as invalid by changing the > > rt_genid which make the old routes invisible. And since we don't > > have rt_check_expire() anymore, we have to wait until we have > > collected gc_thresh (1024) useless routes before rt_garbage_collect= () > > starts to remove some of them (btw. is this intentional). > >=20 > > I think we need a trigger in rt_cache_invalidate() that expires > > all cached pmtu values similar to the routing cache entries. > > For a moment I thought we could just reset the __rt_peer_genid > > value back to zero to mark all cached pmtu values as expired, > > but that's apparently not save to do. So I came to no conclusion > > how to fix this today. Any ideas? >=20 > Oh, right. This problem is secondary. As long as the mtu value is > reflected properly, I'll be happy :) >=20 Well, "ip route flush cache" flushed the cached pmtu informations in 2.6.38 and before, now it does not do it anymore. I guess some users rely on the old behaviour, so it would be nice if we could restore it. I think we can fix this by adding a pmtu_genid, exactly in the same way as we have now the redirect_genid. I'll give this a try.