From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756148Ab1G2K23 (ORCPT ); Fri, 29 Jul 2011 06:28:29 -0400 Received: from mail-wy0-f174.google.com ([74.125.82.174]:45087 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756056Ab1G2K21 (ORCPT ); Fri, 29 Jul 2011 06:28:27 -0400 Date: Fri, 29 Jul 2011 12:25:12 +0200 From: Daniel Vetter To: Keith Packard Cc: Jesse Barnes , Daniel Vetter , Dave Airlie , intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: Re: [Intel-gfx] [PATCH] drm/i915: Hold struct_mutex during hotplug processing Message-ID: <20110729102512.GB2697@phenom.ffwll.local> Mail-Followup-To: Keith Packard , Jesse Barnes , Dave Airlie , intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org References: <1311613829-4990-1-git-send-email-keithp@keithp.com> <20110726121225.3ae7acce@jbarnes-desktop> <20110727090331.60e0c5be@jbarnes-desktop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Operating-System: Linux phenom 3.0.0-rc7-00009-g9095109 User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 28, 2011 at 03:50:00PM -0700, Keith Packard wrote: > On Wed, 27 Jul 2011 09:03:31 -0700, Jesse Barnes wrote: > > On Wed, 27 Jul 2011 02:21:24 -0700 > > Keith Packard wrote: > > > So the work may get executed immediately rather than being run later at > > > some point? > > > > It sure looks that way... but I don't remember any rule about work > > queue items having inter dependencies like this. I've checked the workqueue code and haven't found it to run a work immediately, it's always queued. Further this problem is very easy to diagnose: Even without lockdep the scheduler will notice the stuck task after about 120s and the backtrace should make matters extremely clear. On the other hand if somebody adds some nice state clobbering in the drm helper, we have a very hard bug to track down. Generally modesetting isn't perf critical, so I vote for more locking, just in case. -Daniel -- Daniel Vetter Mail: daniel@ffwll.ch Mobile: +41 (0)79 365 57 48