Re: [Linux-fbdev-devel] [fbdev] Lockdep error

From: Dmitry
Date: Tue Sep 23 2008 - 05:53:48 EST


2008/9/17 Krzysztof Helt <krzysztof.h1@xxxxx>:
> On Mon, 15 Sep 2008 16:21:52 +0400
> Dmitry Baryshkov <dbaryshkov@xxxxxxxxx> wrote:
>
>> Hi,
>>
>> After doing
>> # echo 1 > /sys/class/graphics/fb0/blank
>> I got the following in my kernel log:
>>
>> =============================================
>> [ INFO: possible recursive locking detected ]
>> 2.6.27-rc6-00086-gda63874-dirty #97
>> ---------------------------------------------
>> echo/1564 is trying to acquire lock:
>> ((fb_notifier_list).rwsem){..--}, at: [<c005a384>] __blocking_notifier_call_chain+0x38/0x6c
>>
>
> Does the patch below fix the problem for you?

Sorry for the delay.
Yes, the patch does fix the issue for me. Thank you.

>
> Kind regards,
> Krzysztof
>
> diff -urp linux-ref/drivers/video/console/fbcon.c linux-mm/drivers/video/console/fbcon.c
> --- linux-ref/drivers/video/console/fbcon.c 2008-09-05 23:38:47.000000000 +0200
> +++ linux-mm/drivers/video/console/fbcon.c 2008-09-16 23:30:52.309604454 +0200
> @@ -2400,11 +2400,15 @@ static int fbcon_blank(struct vc_data *v
>
> if (!fbcon_is_inactive(vc, info)) {
> if (ops->blank_state != blank) {
> + int ret = 1;
> +
> ops->blank_state = blank;
> fbcon_cursor(vc, blank ? CM_ERASE : CM_DRAW);
> ops->cursor_flash = (!blank);
>
> - if (fb_blank(info, blank))
> + if (info->fbops->fb_blank)
> + ret = info->fbops->fb_blank(blank, info);
> + if (ret)
> fbcon_generic_blank(vc, info, blank);
> }
>
>



--
With best wishes
Dmitry
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