linux-kernel - Re: [watchdog] watchdog: mei_wdt: request stop on reboot to prevent false positive event

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Message-ID: <f1d58ef7-66ec-acac-4a9d-dcb8b16b3110@roeck-us.net>
Date:   Wed, 9 Nov 2016 06:47:31 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Tomas Winkler <tomas.winkler@...el.com>,
        Wim Van Sebroeck <wim@...ana.be>
Cc:     linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org,
        Alexander Usyskin <alexander.usyskin@...el.com>,
        stable@...r.kernel.org
Subject: Re: [watchdog] watchdog: mei_wdt: request stop on reboot to prevent
 false positive event

On 11/08/2016 07:55 AM, Tomas Winkler wrote:
> From: Alexander Usyskin <alexander.usyskin@...el.com>
>
> Systemd on reboot enables shutdown watchdog that leaves the watchdog
> device open to ensure that even if power down process get stuck the
> platform reboots nonetheless.
> The iamt_wdt is an alarm-only watchdog and can't reboot system, but the
> FW will generate an alarm event reboot was completed in time, as the
> watchdog is not automatically disabled during power cycle.
> So we should request stop watchdog on reboot to eliminate wrong alarm
> from the FW.
>
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Alexander Usyskin <alexander.usyskin@...el.com>
> Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
>  drivers/watchdog/mei_wdt.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/watchdog/mei_wdt.c b/drivers/watchdog/mei_wdt.c
> index e0af52265511..40953fe4db86 100644
> --- a/drivers/watchdog/mei_wdt.c
> +++ b/drivers/watchdog/mei_wdt.c
> @@ -389,6 +389,8 @@ static int mei_wdt_register(struct mei_wdt *wdt)
>  	wdt->wdd.max_timeout = MEI_WDT_MAX_TIMEOUT;
>
>  	watchdog_set_drvdata(&wdt->wdd, wdt);
> +	watchdog_stop_on_reboot(&wdt->wdd);
> +
>  	ret = watchdog_register_device(&wdt->wdd);
>  	if (ret) {
>  		dev_err(dev, "unable to register watchdog device = %d.\n", ret);
>