From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [PATCH net] ipv6: fix RTNL assert fail in DAD Date: Tue, 18 Mar 2014 23:58:11 -0700 Message-ID: <20140318235811.0d8f230a@nehalam.linuxnetplumber.net> References: <20140317161853.2e880469@nehalam.linuxnetplumber.net> <20140318002908.GF12291@order.stressinduktion.org> <20140318175406.78339ffe@nehalam.linuxnetplumber.net> <20140319.001736.730011705431992209.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: hannes@stressinduktion.org, netdev@vger.kernel.org To: David Miller Return-path: Received: from mail-pb0-f46.google.com ([209.85.160.46]:64755 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752555AbaCSG6P (ORCPT ); Wed, 19 Mar 2014 02:58:15 -0400 Received: by mail-pb0-f46.google.com with SMTP id rq2so8437515pbb.19 for ; Tue, 18 Mar 2014 23:58:15 -0700 (PDT) In-Reply-To: <20140319.001736.730011705431992209.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 19 Mar 2014 00:17:36 -0400 (EDT) David Miller wrote: > From: Stephen Hemminger > Date: Tue, 18 Mar 2014 17:54:06 -0700 > > > On Tue, 18 Mar 2014 01:29:08 +0100 > > Hannes Frederic Sowa wrote: > > > >> I wonder if we should put the whole ipv6_ifa_notify infrastructure in a > >> workqueue? I don't like that either and it could add subtile races. > > > > That is option, might be some call chains that already have rtnl_lock held. > > There are TAHI ipv6 conformance tests that expect state changes to be > precisely synchronous. > > And frankly it's pretty reasonable to send two packets back to back, > one which causes the state change and one which tests if the state > change happened, and expect that to work. It is more the timer based state changes that are problematic because they aren't acquire RTNL.