[rtc-linux] Re: [PATCHv3 1/2] watchdog: stmp3xxx: Stop the watchdog on system halt

["Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>]

Hello,

On Wed, Oct 07, 2015 at 12:19:11PM +0000, Harald Geyer wrote:
> This allows the system to actually halt even if userspace forgot to
> disable the watchdog first. Old behaviour was that the watchdog forced
> the system to boot again.
>=20
> Signed-off-by: Harald Geyer <harald@ccbib.org>
> ---
> Changes since v2:
> * split this out as a separate patch
>=20
>  drivers/watchdog/stmp3xxx_rtc_wdt.c |   28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
>=20
> diff --git a/drivers/watchdog/stmp3xxx_rtc_wdt.c b/drivers/watchdog/stmp3=
xxx_rtc_wdt.c
> index 3ee6128..e09a01f 100644
> --- a/drivers/watchdog/stmp3xxx_rtc_wdt.c
> +++ b/drivers/watchdog/stmp3xxx_rtc_wdt.c
> @@ -14,6 +14,8 @@
>  #include <linux/watchdog.h>
>  #include <linux/platform_device.h>
>  #include <linux/stmp3xxx_rtc_wdt.h>
> +#include <linux/notifier.h>
> +#include <linux/reboot.h>
> =20
>  #define WDOG_TICK_RATE 1000 /* 1 kHz clock */
>  #define STMP3XXX_DEFAULT_TIMEOUT 19
> @@ -69,6 +71,28 @@ static struct watchdog_device stmp3xxx_wdd =3D {
>  	.status =3D WATCHDOG_NOWAYOUT_INIT_STATUS,
>  };
> =20
> +static int wdt_notify_sys(struct notifier_block *nb, unsigned long code,
> +			  void *unused)
> +{
> +	struct device *dev =3D watchdog_get_drvdata(&stmp3xxx_wdd);
> +	struct stmp3xxx_wdt_pdata *pdata =3D dev_get_platdata(dev);
> +
> +	switch (code) {
> +	case SYS_DOWN:	/* keep enabled, system might crash while going down */
> +		break;
> +	case SYS_HALT:  /* allow the system to actually halt */

<nitpick>
You used a tab before the comment "keep enabled ...", but spaces for
"allow the system ...".
</nitpick>

> +	case SYS_POWER_OFF:
> +		wdt_stop(&stmp3xxx_wdd);
> +		break;
> +	}
> +
> +	return NOTIFY_DONE;
> +}
> +
> +static struct notifier_block wdt_notifier =3D {
> +	.notifier_call  =3D wdt_notify_sys,

s/  / /

> +};
> +
>  static int stmp3xxx_wdt_probe(struct platform_device *pdev)
>  {
>  	int ret;
> @@ -84,6 +108,9 @@ static int stmp3xxx_wdt_probe(struct platform_device *=
pdev)
>  		return ret;
>  	}
> =20
> +	if (register_reboot_notifier(&wdt_notifier))
> +		dev_warn(&pdev->dev, "cannot register reboot notifier\n");

OK, you don't fail when registering the notifier fails, but ...

>  	dev_info(&pdev->dev, "initialized watchdog with heartbeat %ds\n",
>  			stmp3xxx_wdd.timeout);
>  	return 0;
> @@ -91,6 +118,7 @@ static int stmp3xxx_wdt_probe(struct platform_device *=
pdev)
> =20
>  static int stmp3xxx_wdt_remove(struct platform_device *pdev)
>  {
> +	unregister_reboot_notifier(&wdt_notifier);

... I think it's not ok to unconditionally unregister it then, is it?
(Looking at how unregister_reboot_notifier is implemented it might work
as intended, but if that's only by chance I wouldn't rely on it.)

Best regards
Uwe

>  	watchdog_unregister_device(&stmp3xxx_wdd);
>  	return 0;
>  }
> --=20
> 1.7.10.4
>=20
>=20
>=20

--=20
Pengutronix e.K.                           | Uwe Kleine-K=C3=B6nig         =
   |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

--=20
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