From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Greear Subject: Re: [BUG] RTNL and flush_scheduled_work deadlocks Date: Fri, 16 Feb 2007 08:06:25 -0800 Message-ID: <45D5D681.5060104@candelatech.com> References: <20070216072928.GA1599@ff.dom.local> <45D55FF0.8090309@candelatech.com> <20070216081051.GC1599@ff.dom.local> <45D569E9.7010407@candelatech.com> <20070216090425.GD1599@ff.dom.local> <20070216121245.GE1599@ff.dom.local> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Stephen Hemminger , Francois Romieu , netdev@vger.kernel.org, Kyle Lucke , Raghavendra Koushik , Al Viro To: Jarek Poplawski Return-path: Received: from ns2.lanforge.com ([66.165.47.211]:40025 "EHLO ns2.lanforge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1945962AbXBPQGC (ORCPT ); Fri, 16 Feb 2007 11:06:02 -0500 In-Reply-To: <20070216121245.GE1599@ff.dom.local> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Jarek Poplawski wrote: > On Fri, Feb 16, 2007 at 10:04:25AM +0100, Jarek Poplawski wrote: > >> On Fri, Feb 16, 2007 at 12:23:05AM -0800, Ben Greear wrote: >> > ... > >>> I don't see how asserting it in the rtnl_lock would help anything, >>> because at that >>> point we are about to deadlock anyway... (and this is probably very >>> rare, as mentioned above.) >>> >> But it's happening now. Probably lockdep is not enough >> and rtnl_lock is probably used in too many places, so I >> meant some additional checks would be possible. >> > > And of course it already could be done by DEBUG_MUTEXES or > DEBUG_SPINLOCK, so I gone too far and it's really bad idea. > Well, I had lockdep and all of the locking debugging I could find enabled, but it did not catch this problem..I had to use sysctl -t and manually dig through the backtraces to find the deadlock.... It may be that lockdep could be enhanced to catch this sort of thing.... Ben -- Ben Greear Candela Technologies Inc http://www.candelatech.com