Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756874AbZGEOwY (ORCPT ); Sun, 5 Jul 2009 10:52:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756554AbZGEOwP (ORCPT ); Sun, 5 Jul 2009 10:52:15 -0400 Received: from 124x34x33x190.ap124.ftth.ucom.ne.jp ([124.34.33.190]:55248 "EHLO master.linux-sh.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753239AbZGEOwO (ORCPT ); Sun, 5 Jul 2009 10:52:14 -0400 Date: Sun, 5 Jul 2009 23:52:03 +0900 From: Paul Mundt To: Linus Torvalds Cc: Wu Zhangjin , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mips@linux-mips.org, Krzysztof Helt , Peter Zijlstra , "Rafael J. Wysocki" , Andrew Morton , Ralf Baechle , ???? , zhangfx Subject: Re: [BUG] drivers/video/sis: deadlock introduced by "fbdev: add mutex for fb_mmap locking" Message-ID: <20090705145203.GA8326@linux-sh.org> Mail-Followup-To: Paul Mundt , Linus Torvalds , Wu Zhangjin , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mips@linux-mips.org, Krzysztof Helt , Peter Zijlstra , "Rafael J. Wysocki" , Andrew Morton , Ralf Baechle , ???? , zhangfx References: <1246785112.14240.34.camel@falcon> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2410 Lines: 65 On Sun, Jul 05, 2009 at 07:19:33AM -0700, Linus Torvalds wrote: > > > On Sun, 5 Jul 2009, Wu Zhangjin wrote: > > > > then it works! so, I guess there is a deadlock introduced by the above > > commit. > > Hmm. Perhaps more likely, the 'mm_lock' mutex hasn't even been initialized > yet. We appear to have had that problem with matroxfb and sm501fb, and it > may be more common than that. See commit f50bf2b2. > > That said, I do agree that the mm_lock seems to be causing more problems > than it actually fixes, and maybe we should revert it. Krzysztof? > Looking at this a bit closer, just moving the mutex initialization in to framebuffer_alloc() should basically fix most of these, at least it certainly does for sm501fb and for this sis case as well. So, here's a patch to do that. As an aside note, matroxfb is the odd one out, as it doesn't use framebuffer_alloc() directly for whatever reason. This actually raises an additional issue, in that framebuffer_alloc() is already where other mutexes are initialized, which will simply never happen on matroxfb (suggesting that at least the FB_BACKLIGHT and matroxfb combination will blow up, although perhaps that's not a valid combination). Signed-off-by: Paul Mundt --- drivers/video/fbmem.c | 1 - drivers/video/fbsysfs.c | 2 ++ 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c index 53ea056..27a5271 100644 --- a/drivers/video/fbmem.c +++ b/drivers/video/fbmem.c @@ -1514,7 +1514,6 @@ register_framebuffer(struct fb_info *fb_info) break; fb_info->node = i; mutex_init(&fb_info->lock); - mutex_init(&fb_info->mm_lock); fb_info->dev = device_create(fb_class, fb_info->device, MKDEV(FB_MAJOR, i), NULL, "fb%d", i); diff --git a/drivers/video/fbsysfs.c b/drivers/video/fbsysfs.c index d4a2c11..dd413ad 100644 --- a/drivers/video/fbsysfs.c +++ b/drivers/video/fbsysfs.c @@ -62,6 +62,8 @@ struct fb_info *framebuffer_alloc(size_t size, struct device *dev) mutex_init(&info->bl_curve_mutex); #endif + mutex_init(&info->mm_lock); + return info; #undef PADDING #undef BYTES_PER_LONG -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/