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Sender: Guenter Roeck <groeck7@gmail.com>
To:     Curtis Klein <curtis.klein@hpe.com>, wim@linux-watchdog.org
Cc:     linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org
References: <1624751265-24785-1-git-send-email-curtis.klein@hpe.com>
From:   Guenter Roeck <linux@roeck-us.net>
Subject: Re: [PATCH] watchdog: only run driver set_pretimeout op if device
 supports it
Message-ID: <42547712-88c9-b432-f049-f2db8447739d@roeck-us.net>
Date:   Sun, 27 Jun 2021 08:01:04 -0700
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On 6/26/21 4:47 PM, Curtis Klein wrote:
> Some watchdog devices might conditionally support pretimeouts (e.g. if
> an interrupt is exposed for the device) but some watchdog drivers might
> still define the set_pretimeout operation (e.g. the mtk_wdt driver) and
> indicate support at runtime through the WDIOF_PRETIMEOUT flag. If the
> kernel is compiled with CONFIG_WATCHDOG_HRTIMER_PRETIMEOUT enabled,
> watchdog_set_pretimeout would run the driver specific set_pretimeout
> even if WDIOF_PRETIMEOUT is not set which might have unintended
> consequences.
> 
> So this change checks that the device flags and only runs the driver
> operation if pretimeouts are supported.
> 
> Signed-off-by: Curtis Klein <curtis.klein@hpe.com>

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

> ---
>   drivers/watchdog/watchdog_dev.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
> index 3bab324..5bf795c 100644
> --- a/drivers/watchdog/watchdog_dev.c
> +++ b/drivers/watchdog/watchdog_dev.c
> @@ -401,7 +401,7 @@ static int watchdog_set_pretimeout(struct watchdog_device *wdd,
>   	if (watchdog_pretimeout_invalid(wdd, timeout))
>   		return -EINVAL;
>   
> -	if (wdd->ops->set_pretimeout)
> +	if (wdd->ops->set_pretimeout && (wdd->info->options & WDIOF_PRETIMEOUT))
>   		err = wdd->ops->set_pretimeout(wdd, timeout);
>   	else
>   		wdd->pretimeout = timeout;
>