Subject: Re: [PATCH] watchdog: add CONFIG_WATCHDOG_NOWAYOUT support to PowerPC Book-E watchdog driver

From: Timur Tabi <[email-masked]>
Date: Fri, 3 Dec 2010 12:22:30 -0600

Josh Boyer wrote:
> I'm confused why you can't use booke_wdt_enabled for the purposes of the
> device having been opened.  It seems the use of the wdt_is_active
> basically duplicates this functionalit (and oddly with the bit
> manipulation instead of just atomic_inc/dec).

Because the watchdog can be enabled even when the driver is not open.
booke_wdt_enabled is also initialized in setup_32.c.  So booke_wdt_enabled
represents the watchdog hardwre, whereas wdt_is_active represents the open
condition of /dev/watchdog.

However, now that I think about it, maybe that just causes confusion.  If the
watchdog is already running because of a command-line parameter, should we
prevent /dev/watchdog from ever being opened?  If you're okay with that, then I
can combine the two variables.

> If you were to keep this variable instead of just using
> booke_wdt_enabled, wouldn't it be more correct to have the clear_bit
> only done inside the #ifndef?  The timer is very much still active if
> NOWAYOUT is set...

In this case, yes.

-- 
Timur Tabi
Linux kernel developer at Freescale