From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [PATCH RFC net-next] net: Allow name change of IFF_UP interfaces Date: Thu, 10 Aug 2017 10:16:19 -0700 Message-ID: <20170810101619.15142772@xeon-e3> References: <20170810141358.GD24790@lunn.ch> <87lgmrsawo.fsf@vitty.brq.redhat.com> <20170810162722.GH24790@lunn.ch> <20170810.094803.1621536453262110983.davem@davemloft.net> <88b507b7-1b60-5100-3e31-b68263f0f631@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: David Miller , andrew@lunn.ch, vkuznets@redhat.com, eric.dumazet@gmail.com, netdev@vger.kernel.org, edumazet@google.com To: David Ahern Return-path: Received: from mail-pf0-f179.google.com ([209.85.192.179]:33031 "EHLO mail-pf0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752559AbdHJRQV (ORCPT ); Thu, 10 Aug 2017 13:16:21 -0400 Received: by mail-pf0-f179.google.com with SMTP id h68so5601111pfk.0 for ; Thu, 10 Aug 2017 10:16:21 -0700 (PDT) In-Reply-To: <88b507b7-1b60-5100-3e31-b68263f0f631@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, 10 Aug 2017 10:55:01 -0600 David Ahern wrote: > On 8/10/17 10:48 AM, David Miller wrote: > > From: Andrew Lunn > > Date: Thu, 10 Aug 2017 18:27:22 +0200 > > > >> On Thu, Aug 10, 2017 at 05:24:55PM +0200, Vitaly Kuznetsov wrote: > >>> Andrew Lunn writes: > >>> > >>>>> We are - rtnetlink_event() does the job. We, however, don't have a > >>>>> special IFLA_EVENT_* for name change and end up with IFLA_EVENT_NONE. > >>>> > >>>> What is in this event? Old and new name? Just the new name? > >>> > >>> Basically, it's everything we know about the interface - type, index, > >>> name, mtu, qdisc, ... - see rtnl_fill_ifinfo(). Back to your question - > >>> it's only the new name. > >> > >> So the program needs to keep track of ifindex to know which interface > >> has changed name. Doable. > >> > >> I still expect this has the potential to break something. You probably > >> should be asking on linux-api for the API experts opinion. > > > > But a greater point is that nobody is monitoring device renames > > explicitly right now. > > Just to throw in an example: > https://github.com/kobolabs/dhcpcd/blob/kobo/if-linux.c#L761 > > Learned of its use from a recent regression: > https://bugzilla.kernel.org/show_bug.cgi?id=196355 Quagga is another example of what might break. Especially with all the new forks..