Re: [PATCH 2/2] watchdog: gpio-wdt: Add panic notifier

[Guenter Roeck <linux@roeck-us.net>]

On 11/09/2015 01:55 AM, Alexander Stein wrote:
> This notifier is required when the watchdog is configured as always running
> because in this case the watchdog will be triggered when the kernel panics
> at boot before any application could open the device, e.g. because the
> rootfs is broken. This should result in a resetting system. Thus we
> register a panic notifier which stops triggering the watchdog.
>

Shouldn't the timer be stopped instead ?

Copying Uwe for additional input.

Thanks,
Guenter

> Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
> ---
>   drivers/watchdog/gpio_wdt.c | 20 ++++++++++++++++++++
>   1 file changed, 20 insertions(+)
>
> diff --git a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c
> index c7b8a06..aaa0815 100644
> --- a/drivers/watchdog/gpio_wdt.c
> +++ b/drivers/watchdog/gpio_wdt.c
> @@ -37,6 +37,7 @@ struct gpio_wdt_priv {
>   	unsigned int		hw_margin;
>   	unsigned long		last_jiffies;
>   	struct notifier_block	reboot_notifier;
> +	struct notifier_block	panic_notifier;
>   	struct timer_list	timer;
>   	struct watchdog_device	wdd;
>   };
> @@ -146,6 +147,17 @@ static int gpio_wdt_notify_sys(struct notifier_block *nb, unsigned long code,
>   	return NOTIFY_DONE;
>   }
>
> +static int gpio_wdt_notify_panic(struct notifier_block *nb, unsigned long code,
> +			       void *unused)
> +{
> +	struct gpio_wdt_priv *priv = container_of(nb, struct gpio_wdt_priv,
> +						  panic_notifier);
> +
> +	gpio_wdt_disable(priv);
> +
> +	return NOTIFY_DONE;
> +}
> +
>   static const struct watchdog_info gpio_wdt_ident = {
>   	.options	= WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
>   			  WDIOF_SETTIMEOUT,
> @@ -233,11 +245,19 @@ static int gpio_wdt_probe(struct platform_device *pdev)
>   	if (ret)
>   		goto error_unregister;
>
> +	priv->panic_notifier.notifier_call = gpio_wdt_notify_panic;
> +	ret = atomic_notifier_chain_register(&panic_notifier_list,
> +					     &priv->panic_notifier);
> +	if (ret)
> +		goto error_unregister_notify;
> +
>   	if (priv->always_running)
>   		gpio_wdt_start_impl(priv);
>
>   	return 0;
>
> +error_unregister_notify:
> +	unregister_reboot_notifier(&priv->reboot_notifier);
>   error_unregister:
>   	watchdog_unregister_device(&priv->wdd);
>   	return ret;
>