From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: [PATCH] veth: Cleanly handle a missing peer_tb argument on creation. Date: Wed, 12 Sep 2007 09:25:45 -0600 Message-ID: References: <46E7F466.1060704@openvz.org> <46E7FC64.5030604@openvz.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Miller , Patrick McHardy , netdev@vger.kernel.org, Stephen Hemminger To: Pavel Emelyanov Return-path: Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:46304 "EHLO ebiederm.dsl.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933522AbXILP0S (ORCPT ); Wed, 12 Sep 2007 11:26:18 -0400 In-Reply-To: <46E7FC64.5030604@openvz.org> (Pavel Emelyanov's message of "Wed, 12 Sep 2007 18:49:08 +0400") Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Pavel Emelyanov writes: > Eric W. Biederman wrote: >> Pavel Emelyanov writes: >> >>>> + } >>>> >>>> - tbp = peer_tb; >>>> - } else >>>> - tbp = tb; >>> The intention of this part was to get the same parameters for >>> peer as for the first device if no "peer" argument was specified >>> for ip utility. Does it still work? >> >> I know it is problematic because we try to assign the same name >> to both network devices, if we assign a name to the primary >> network device. That can't work. > > This can - as you can see I reallocate the name lower. Hmm. I just see: if (tbp[IFLA_IFNAME]) nla_strlcpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ); Then lower I see: if (tb[IFLA_IFNAME]) nla_strlcpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ); If (tb == tbp) then dev->name == ifname Unless I'm completely misreading that code. >> Beyond that I had some really weird crashes while testing this >> piece of code, especially when I did not specify a peer parameter. > > Can you please give me the exact command that caused an oops. > I try simple ip link add type veth and everything is just fine. It might have been 64bit specific. What I have in my history is: ./ip/ip link add veth23 type veth I forget exactly how it failed but as I recall it wasn't as nice as an oops. My memory may be a bit foggy though. If I haven't provided a bit enough clue I guess I can go back and remove the patch and try to reproduce the failure again. >> So it was just easier to avoid the problem with this patch then >> to completely root cause it. > > Let me handle this problem. AFAIR this was one of wishes from > Patrick that we make two equal devices in case peer is not given, > not just the default peer. Ok. I have if we can track down the weird cases I have no problem if we handle this. I think it still might be simpler if just copy tb onto peer_tb instead of using tbp. Eric