linux-kernel - Re: [PATCH v2 06/16] watchdog: hpwdt: drop warning after calling watchdog_init

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Date:   Wed, 24 Apr 2019 10:38:07 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Wolfram Sang <wsa@...-dreams.de>
Cc:     Guenter Roeck <linux@...ck-us.net>,
        Jerry Hoemann <jerry.hoemann@....com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Linux Watchdog Mailing List <linux-watchdog@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 06/16] watchdog: hpwdt: drop warning after calling watchdog_init_timeout

Hi Wolfram,

On Wed, Apr 17, 2019 at 9:46 PM Wolfram Sang <wsa@...-dreams.de> wrote:
> > Yes, that works as well. Note that it will actually print something like
> > "watchdog: <device>: ..." due to the pr_fmt() at the top of watchdog_core.c.
> > I guess that should be ok.
>
> I have the following diff applied on top of patch 2. Works with and
> without a parent device. I am not super happy casting 'identity' but
> since its u8-type is exported to userspace, I think we can't avoid it.
> Guenter, is this cast safe? Here is the diff:
>
> diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
> index cd3ca6b366ef..62be9e52a4de 100644
> --- a/drivers/watchdog/watchdog_core.c
> +++ b/drivers/watchdog/watchdog_core.c
> @@ -115,6 +115,8 @@ static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
>  int watchdog_init_timeout(struct watchdog_device *wdd,
>                                 unsigned int timeout_parm, struct device *dev)
>  {
> +       const char *dev_str = wdd->parent ? dev_name(wdd->parent) :
> +                             (const char *)wdd->info->identity;

    struct watchdog_info {
            ...
            __u8  identity[32];     /* Identity of the board */
    };

Is identity[] guaranteed to be NUL-terminated?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds