From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755332Ab2DTRZr (ORCPT ); Fri, 20 Apr 2012 13:25:47 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:33006 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752637Ab2DTRZq (ORCPT ); Fri, 20 Apr 2012 13:25:46 -0400 Date: Fri, 20 Apr 2012 18:25:40 +0100 From: Andy Whitcroft To: Dave Airlie Cc: David Airlie , dri-devel@lists.freedesktop.org, Jesse Barnes , Bryce Harrington , linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/1] [RFC] DRM locking issues during early open Message-ID: <20120420172540.GF3467@shadowen.org> References: <1334852525-14950-1-git-send-email-apw@canonical.com> <20120420103110.GD3467@shadowen.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Fri, Apr 20, 2012 at 11:34:43AM +0100, Dave Airlie wrote: > > > > I may be reading things wrong but the initialisation does indeed hold > > drm_global_mutex, but and back when this first occured we would have > > been using kernel_lock() which was at least partially reentrant right? > > Yup if we slept with the BKL held we'd have allowed others to get past it, > but also I introduced the global mutex in pci a while back Yeah I have managed to get access to more details on the bug, and actually we are opening the drm device successfully, we then attempt a DRM_SETVERSION ioctl on it and it is that that appears to fail both for 1.4 and 1.1. It is somewhat perplexing to understand how that is possible, though I will note that the stub f_ops do not contain an ioctl op but I cannot see any mechanism by which we might return a validly open file without putting the driver specific ops in it. -apw