From mboxrd@z Thu Jan 1 00:00:00 1970 From: Geoff Levand Subject: [patch] fbcon: Fix workqueue shutdown Date: Wed, 3 Dec 2008 16:23:12 -0800 Message-ID: <493722F0.5070707@am.sony.com> References: <4909EB41.40100@am.sony.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from sfi-mx-4.v28.ch3.sourceforge.com ([172.29.28.124] helo=mx.sourceforge.net) by 335xhf1.ch3.sourceforge.com with esmtp (Exim 4.69) (envelope-from ) id 1L820O-00056V-CX for linux-fbdev-devel@lists.sourceforge.net; Thu, 04 Dec 2008 00:23:44 +0000 Received: from outbound-wa4.frontbridge.com ([216.32.181.16] helo=WA4EHSOBE006.bigfish.com) by 1b2kzd1.ch3.sourceforge.com with esmtps (TLSv1:RC4-MD5:128) (Exim 4.69) id 1L820K-0005Nu-EF for linux-fbdev-devel@lists.sourceforge.net; Thu, 04 Dec 2008 00:23:44 +0000 In-Reply-To: <4909EB41.40100@am.sony.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-fbdev-devel-bounces@lists.sourceforge.net To: adaplas@gmail.com Cc: Geert Uytterhoeven , Andrew Morton , linux-fbdev-devel@lists.sourceforge.net Add a call to cancel_work_sync() in fbcon_exit() to cancel any pending work in the fbcon workqueue. Also, change the assignment of the workqueue function info->queue.func from NULL to fb_flashcursor(), and add a corresponding check in fb_flashcursor() to exit immediately if the variable fbcon_has_exited is set. The current implementation of fbcon_exit() sets the fbcon workqueue function info->queue.func to NULL, but does not assure that there is no work pending when it does so. On occasion, depending on system timing, there will still be pending work in the queue when fbcon_exit() is called. This results in a null pointer deference when run_workqueue() tries to call the queue's work function. Fixes errors on shutdown similar to these: Console: switching to colour dummy device 80x25 Unable to handle kernel paging request for data at address 0x00000000 Signed-off-by: Geoff Levand --- Hi, This is a resend of my 10/30/2008 patch. I didn't get any feed back. I was hoping to get this bug fixed for 2.6.29. -Geoff drivers/video/console/fbcon.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) --- a/drivers/video/console/fbcon.c +++ b/drivers/video/console/fbcon.c @@ -394,13 +394,19 @@ static void fbcon_update_softback(struct static void fb_flashcursor(struct work_struct *work) { - struct fb_info *info = container_of(work, struct fb_info, queue); - struct fbcon_ops *ops = info->fbcon_par; + struct fb_info *info; + struct fbcon_ops *ops; struct display *p; struct vc_data *vc = NULL; int c; int mode; + if (fbcon_has_exited) + return; + + info = container_of(work, struct fb_info, queue); + ops = info->fbcon_par; + acquire_console_sem(); if (ops && ops->currcon != -1) vc = vc_cons[ops->currcon].d; @@ -3534,12 +3540,18 @@ static void fbcon_exit(void) softback_buf = 0UL; for (i = 0; i < FB_MAX; i++) { + int pending; + mapped = 0; info = registered_fb[i]; if (info == NULL) continue; + pending = cancel_work_sync(&info->queue); + DPRINTK("fbcon: %s pending work\n", (pending ? "canceled" : + "no")); + for (j = first_fb_vc; j <= last_fb_vc; j++) { if (con2fb_map[j] == i) mapped = 1; @@ -3558,9 +3570,6 @@ static void fbcon_exit(void) kfree(info->fbcon_par); info->fbcon_par = NULL; } - - if (info->queue.func == fb_flashcursor) - info->queue.func = NULL; } } ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/