From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from zone0.gcu-squad.org ([212.85.147.21]:21656 "EHLO services.gcu-squad.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750860AbZCBTFY (ORCPT ); Mon, 2 Mar 2009 14:05:24 -0500 Date: Mon, 2 Mar 2009 20:05:13 +0100 From: Jean Delvare To: Andy Walls Cc: linux-media@vger.kernel.org Subject: Re: General protection fault on rmmod cx8800 Message-ID: <20090302200513.7fc3568e@hyperion.delvare> In-Reply-To: <20090302170349.18c8fd75@hyperion.delvare> References: <20090215214108.34f31c39@hyperion.delvare> <20090302133936.00899692@hyperion.delvare> <1236003365.3071.6.camel@palomino.walls.org> <20090302170349.18c8fd75@hyperion.delvare> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: On Mon, 2 Mar 2009 17:03:49 +0100, Jean Delvare wrote: > As far as I can see the key difference between bttv-input and > cx88-input is that bttv-input only uses a simple self-rearming timer, > while cx88-input uses a timer and a separate workqueue. The timer runs > the workqueue, which rearms the timer, etc. When you flush the timer, > the separate workqueue can be still active. I presume this is what > happens on my system. I guess the reason for the separate workqueue is > that the processing may take some time and we don't want to hurt the > system's performance? > > So we need to flush both the event workqueue (with > flush_scheduled_work) and the separate workqueue (with > flush_workqueue), at the same time, otherwise the active one may rearm > the flushed one again. This looks tricky, as obviously we can't flush > both at the exact same time. Alternatively, if we could get rid of one > of the queues, we'd have only one that needs flushing, this would be a > lot easier... Switching to delayed_work seems to do the trick (note this is a 2.6.28 patch): --- drivers/media/video/cx88/cx88-input.c | 26 ++++++++------------------ 1 file changed, 8 insertions(+), 18 deletions(-) --- linux-2.6.28.orig/drivers/media/video/cx88/cx88-input.c 2009-03-02 19:11:24.000000000 +0100 +++ linux-2.6.28/drivers/media/video/cx88/cx88-input.c 2009-03-02 19:49:31.000000000 +0100 @@ -48,8 +48,7 @@ struct cx88_IR { /* poll external decoder */ int polling; - struct work_struct work; - struct timer_list timer; + struct delayed_work work; u32 gpio_addr; u32 last_gpio; u32 mask_keycode; @@ -143,27 +142,20 @@ static void cx88_ir_handle_key(struct cx } } -static void ir_timer(unsigned long data) -{ - struct cx88_IR *ir = (struct cx88_IR *)data; - - schedule_work(&ir->work); -} - static void cx88_ir_work(struct work_struct *work) { - struct cx88_IR *ir = container_of(work, struct cx88_IR, work); + struct delayed_work *dwork = container_of(work, struct delayed_work, work); + struct cx88_IR *ir = container_of(dwork, struct cx88_IR, work); cx88_ir_handle_key(ir); - mod_timer(&ir->timer, jiffies + msecs_to_jiffies(ir->polling)); + schedule_delayed_work(dwork, msecs_to_jiffies(ir->polling)); } void cx88_ir_start(struct cx88_core *core, struct cx88_IR *ir) { if (ir->polling) { - setup_timer(&ir->timer, ir_timer, (unsigned long)ir); - INIT_WORK(&ir->work, cx88_ir_work); - schedule_work(&ir->work); + INIT_DELAYED_WORK(&ir->work, cx88_ir_work); + schedule_delayed_work(&ir->work, msecs_to_jiffies(ir->polling)); } if (ir->sampling) { core->pci_irqmask |= PCI_INT_IR_SMPINT; @@ -179,10 +171,8 @@ void cx88_ir_stop(struct cx88_core *core core->pci_irqmask &= ~PCI_INT_IR_SMPINT; } - if (ir->polling) { - del_timer_sync(&ir->timer); - flush_scheduled_work(); - } + if (ir->polling) + cancel_delayed_work_sync(&ir->work); } /* ---------------------------------------------------------------------- */ At least I didn't have any general protection fault with this patch applied. Comments? Thanks, -- Jean Delvare