linux-kernel - Re: [PATCH] fbcon: initialize blink interval before calling fb_set

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Message-ID: <1444423715.2845.29.camel@kernel.crashing.org>
Date:	Sat, 10 Oct 2015 07:48:35 +1100
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Scot Doyle <lkml14@...tdoyle.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Alistair Popple <alistair@...ple.id.au>,
	Pavel Machek <pavel@....cz>, airlied@...hat.com,
	linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fbcon: initialize blink interval before calling
 fb_set_par

On Fri, 2015-10-09 at 15:08 +0000, Scot Doyle wrote:
> Since commit 27a4c827c34ac4256a190cc9d24607f953c1c459
>     fbcon: use the cursor blink interval provided by vt
> 
> a PPC64LE kernel fails to boot when fbcon_add_cursor_timer uses an
> uninitialized ops->cur_blink_jiffies. Prevent by initializing
> in fbcon_init before the call to info->fbops->fb_set_par.

> Reported-and-tested-by: Alistair Popple <alistair@...ple.id.au>
> Signed-off-by: Scot Doyle <lkml14@...tdoyle.com>

Please add

CC: <stable@...r.kernel.org> [v4.2]

This bug will cause any machine using fbcon to occasionally fail
to boot due to having a timer callback try to mod_timer with
"jiffies + 0" without an exit condition.

Cheers,
Ben.

> ---
>  drivers/video/console/fbcon.c | 1 +
>  1 file changed, 1 insertion(+) 
> 
> diff --git a/drivers/video/console/fbcon.c
> b/drivers/video/console/fbcon.c
> index 1aaf893..92f3949 100644
> --- a/drivers/video/console/fbcon.c
> +++ b/drivers/video/console/fbcon.c
> @@ -1093,6 +1093,7 @@ static void fbcon_init(struct vc_data *vc, int
> init)
>                 con_copy_unimap(vc, svc);
>  
>         ops = info->fbcon_par;
> +       ops->cur_blink_jiffies = msecs_to_jiffies(vc
> ->vc_cur_blink_ms);
>         p->con_rotate = initial_rotation;
>         set_blitting_type(vc, info);
>  
> -- 
> 2.1.4
> 
> --
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