From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Benc Subject: Re: [PATCH net] net: try harder to not reuse ifindex when moving interfaces Date: Wed, 21 Oct 2015 16:46:13 +0200 Message-ID: <20151021164613.24650836@griffin> References: <294c7a9df554506e684adbeb9bbed070e6fed260.1444993627.git.jbenc@redhat.com> <20151021.074332.1709904332480699231.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, thaller@redhat.com To: David Miller Return-path: Received: from mx1.redhat.com ([209.132.183.28]:40916 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751996AbbJUOqQ (ORCPT ); Wed, 21 Oct 2015 10:46:16 -0400 In-Reply-To: <20151021.074332.1709904332480699231.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 21 Oct 2015 07:43:32 -0700 (PDT), David Miller wrote: > Fix the real problem, then come talk to us. I don't think the real problem is fixable, given that any kind of unique non-settable identifier would break CRIU. And anything settable will have the exact same problem. All we can do is narrowing the race window. For example, we could always alloc a new ifindex when moving interfaces between name spaces. That would be probably the tiniest race window we could get to (still not zero!) but I guess it would break apps that assume that ifindex doesn't change when moving interfaces between name spaces (which is not true, such apps are already broken, they just happen to work in 99% of cases). The second best solution that doesn't break those apps at the cost of leaving the race window wider, is this patch. But whatever, I don't care enough about this. Jiri -- Jiri Benc