Re: Query: Best way to know if a watchdog is active (kicked)

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

On 08/17/2015 10:15 PM, Pratyush Anand wrote:
> Hi,
>
> I am looking for the best way to know if a watchdog has been kicked and active.
>
> I can see a way is to read timeout(WDIOC_GETTIMEOUT) and  timeleft(
> WDIOC_GETTIMELEFT). If they do not match, it means that wdt is active.
>
> But what if we tried to read timeleft just in time when watchdog daemon/or some
> other application had kicked it. May be we read timeleft twice at the interval
> of 1 sec.
>
> Please let me know if there is any other alternative which could be a better way
> to know if watchdog is active?  Or may be it would be good to implement an ioctl
> WDIOC_ACTIVE?
>

Normally the watchdog is active if the watchdog device is open, unless the
application controlling it explicitly disabled it with WDIOC_SETOPTIONS.
Therefore, the controlling application should always know the status.
A different application can not open the watchdog device, so it won't be
able to get its status using an ioctl anyway.

Why is that insufficient ?

Guenter