Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751401AbcCFQaC (ORCPT ); Sun, 6 Mar 2016 11:30:02 -0500 Received: from mail-wm0-f41.google.com ([74.125.82.41]:35992 "EHLO mail-wm0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751250AbcCFQ3w (ORCPT ); Sun, 6 Mar 2016 11:29:52 -0500 Date: Sun, 6 Mar 2016 17:29:51 +0100 From: Daniel Vetter To: Douglas Anderson Cc: David Airlie , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: Re: [PATCH] drm: Check for connector->state NULL in drm_atomic_add_affected_connectors Message-ID: <20160306162951.GA14170@phenom.ffwll.local> Mail-Followup-To: Douglas Anderson , David Airlie , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org References: <1457135033-11791-1-git-send-email-dianders@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1457135033-11791-1-git-send-email-dianders@chromium.org> X-Operating-System: Linux phenom 4.3.0-1-amd64 User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2585 Lines: 64 On Fri, Mar 04, 2016 at 03:43:53PM -0800, Douglas Anderson wrote: > On a system I'm doing development on I found a crash. The crawl looked > like: > > PC is at drm_atomic_add_affected_connectors+0x98/0xe8 > ... > drm_atomic_add_affected_connectors from __drm_atomic_helper_set_config+0x218/0x344 > __drm_atomic_helper_set_config from restore_fbdev_mode+0x108/0x250 > restore_fbdev_mode from drm_fb_helper_restore_fbdev_mode_unlocked+0x3c/0x80 > drm_fb_helper_restore_fbdev_mode_unlocked from rockchip_drm_lastclose+0x1c/0x20 > rockchip_drm_lastclose from drm_lastclose+0x4c/0x104 > drm_lastclose from drm_release+0x424/0x47c > drm_release from __fput+0xf8/0x1d4 > __fput from ____fput+0x18/0x1c > ____fput from task_work_run+0xa8/0xbc > task_work_run from do_exit+0x448/0x91c > do_exit from do_group_exit+0x5c/0xcc > do_group_exit from get_signal+0x4dc/0x57c > get_signal from do_signal+0x9c/0x3b4 > do_signal from do_work_pending+0x60/0xb8 > do_work_pending from slow_work_pending+0xc/0x20 > > I found that I could fix the crash by checking connector->state against > NULL. This isn't code I'm familiar with and I didn't dig too deep, so > I'd appreciate any opinions about whether this is a sane thing to do. > Note that I don't actually have graphics up on my system at the moment, > so perhaps this is all just a symptom of the strange state I'm in. > > Signed-off-by: Douglas Anderson This is a driver bug - under atomic the assumption is that there is _always_ a current software state. Most driver set up the initial "everything off" state in the ->reset functions. -Daniel > --- > drivers/gpu/drm/drm_atomic.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c > index 8fb469c4e4b8..3377d7ddc6d1 100644 > --- a/drivers/gpu/drm/drm_atomic.c > +++ b/drivers/gpu/drm/drm_atomic.c > @@ -1147,7 +1147,7 @@ drm_atomic_add_affected_connectors(struct drm_atomic_state *state, > * current configuration. > */ > drm_for_each_connector(connector, state->dev) { > - if (connector->state->crtc != crtc) > + if (!connector->state || connector->state->crtc != crtc) > continue; > > conn_state = drm_atomic_get_connector_state(state, connector); > -- > 2.7.0.rc3.207.g0ac5344 > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch