Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751640AbWIUV4X (ORCPT ); Thu, 21 Sep 2006 17:56:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751647AbWIUV4X (ORCPT ); Thu, 21 Sep 2006 17:56:23 -0400 Received: from hansmi.home.forkbomb.ch ([213.144.146.165]:33053 "EHLO hansmi.home.forkbomb.ch") by vger.kernel.org with ESMTP id S1751640AbWIUV4W (ORCPT ); Thu, 21 Sep 2006 17:56:22 -0400 Date: Thu, 21 Sep 2006 23:56:20 +0200 From: Michael Hanselmann To: olaf@aepfle.de Cc: linux-kernel@vger.kernel.org, linux-fbdev-devel@lists.sourceforge.net, "Antonino A. Daplas" , Daniel R Thompson , Jon Smirl , akpm@osdl.org Subject: Re: backlight: oops in __mutex_lock_slowpath during head /sys/class/graphics/fb0/* in 2.6.18 Message-ID: <20060921215620.GA9518@hansmi.ch> References: <20060921121952.GA16927@aepfle.de> <20060921123742.ec225cc2.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060921123742.ec225cc2.akpm@osdl.org> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1901 Lines: 55 On Thu, Sep 21, 2006 at 12:37:42PM -0700, Andrew Morton wrote: > On Thu, 21 Sep 2006 14:19:52 +0200 > Olaf Hering wrote: > > The bl_curve code has some room for improvement. Agreed. > > inst-sys:~ # dmesg > > valkyriefb: vmode 13 does not support cmode 1. > > Unable to handle kernel paging request for data at address 0x00000000 > > Faulting instruction address: 0xc02c7bd8 Seems like not all drivers use the framebuffer_alloc() function and won't have an initialized mutex. But those don't have a backlight, anyway. What about the patch below? Does it work for you? Signed-off-by: Michael Hanselmann --- diff -Nrup --exclude-from linux-exclude-from linux-2.6.18.orig/drivers/video/fbsysfs.c linux-2.6.18/drivers/video/fbsysfs.c --- linux-2.6.18.orig/drivers/video/fbsysfs.c 2006-09-21 23:40:06.000000000 +0200 +++ linux-2.6.18/drivers/video/fbsysfs.c 2006-09-21 23:50:00.000000000 +0200 @@ -397,6 +397,12 @@ static ssize_t store_bl_curve(struct cla u8 tmp_curve[FB_BACKLIGHT_LEVELS]; unsigned int i; + /* Some drivers don't use framebuffer_alloc(), but those also + * don't have backlights. + */ + if (!fb_info || !fb_info->bl_dev) + return -ENODEV; + if (count != (FB_BACKLIGHT_LEVELS / 8 * 24)) return -EINVAL; @@ -430,6 +436,12 @@ static ssize_t show_bl_curve(struct clas ssize_t len = 0; unsigned int i; + /* Some drivers don't use framebuffer_alloc(), but those also + * don't have backlights. + */ + if (!fb_info || !fb_info->bl_dev) + return -ENODEV; + mutex_lock(&fb_info->bl_mutex); for (i = 0; i < FB_BACKLIGHT_LEVELS; i += 8) len += snprintf(&buf[len], PAGE_SIZE, - 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/