linux-kernel - Re: [PATCH] fbcon: warn on invalid cursor blink intervals

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Date:	Fri, 20 May 2016 10:17:08 +0800
From:	Ming Lei <ming.lei@...onical.com>
To:	Scot Doyle <lkml14@...tdoyle.com>
Cc:	Tomi Valkeinen <tomi.valkeinen@...com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	David Daney <david.daney@...ium.com>,
	Dann Frazier <dann.frazier@...onical.com>,
	Jeremy Kerr <jk@...abs.org>,
	Peter Hurley <peter@...leysoftware.com>,
	Pavel Machek <pavel@....cz>, Jonathan Liu <net147@...il.com>,
	Alistair Popple <alistair@...ple.id.au>,
	Jean-Philippe Brucker <jean-philippe.brucker@....com>,
	"Chintakuntla, Radha" <Radha.Chintakuntla@...iumnetworks.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.com>, David Airlie <airlied@...ux.ie>,
	David Daney <ddaney.cavm@...il.com>,
	dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	stable <stable@...r.kernel.org>
Subject: Re: [PATCH] fbcon: warn on invalid cursor blink intervals

On Fri, May 20, 2016 at 6:31 AM, Scot Doyle <lkml14@...tdoyle.com> wrote:
> Two systems are locking on boot [1] because ops->cur_blink_jiffies
> is set to zero from vc->vc_cur_blink_ms.
>
> Ignore such invalid intervals and log a warning.
>
> [1] https://bugs.launchpad.net/bugs/1574814
>
> Suggested-by: David Daney <david.daney@...ium.com>
> Signed-off-by: Scot Doyle <lkml14@...tdoyle.com>
> Cc: <stable@...r.kernel.org> [v4.2]

Not sure this one is needed for stable because it justs dumps
a warning, and not set a valid period to ops->cur_blink_jiffies.

So I guess other fix patch is still required for the soft lockup issue, right?

Thanks,

> ---
>  drivers/video/console/fbcon.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
> index 6e92917..fad5b89 100644
> --- a/drivers/video/console/fbcon.c
> +++ b/drivers/video/console/fbcon.c
> @@ -1095,7 +1095,13 @@ 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);
> +
> +       if (vc->vc_cur_blink_ms >= 50)
> +               ops->cur_blink_jiffies =
> +                   msecs_to_jiffies(vc->vc_cur_blink_ms);
> +       else
> +               WARN_ONCE(1, "blink interval < 50 ms");
> +
>         p->con_rotate = initial_rotation;
>         set_blitting_type(vc, info);
>
> @@ -1309,7 +1315,11 @@ static void fbcon_cursor(struct vc_data *vc, int mode)
>         int y;
>         int c = scr_readw((u16 *) vc->vc_pos);
>
> -       ops->cur_blink_jiffies = msecs_to_jiffies(vc->vc_cur_blink_ms);
> +       if (vc->vc_cur_blink_ms >= 50)
> +               ops->cur_blink_jiffies =
> +                   msecs_to_jiffies(vc->vc_cur_blink_ms);
> +       else
> +               WARN_ONCE(1, "blink interval < 50 ms");
>
>         if (fbcon_is_inactive(vc, info) || vc->vc_deccm != 1)
>                 return;
> --
> 2.1.4
>