[PATCH] watchdog: fix error in probe() of s3c2410_wdt (reset at booting)

[Wim Van Sebroeck]

Hi,

On Fri, Jan 13, 2012 at 11:11:17AM +0000, Russell King - ARM Linux wrote:

> On Fri, Jan 13, 2012 at 02:14:23PM +0900, MyungJoo Ham wrote:
> > Probe function of s3c2410 watchdog calls request_irq before initializing
> > required value (wdt_count). This incurs resetting watchdog counter value
> > and watchdog-reboot during booting up.
> > 
> > This patch addresses such an issue by calling request_irq later.
> > 
> > Error handling in probe function and calling oder in remove function are
> > also revised accordingly.
> 
> On the other hand, this patch violates the general principle that you set
> the device up _before_ you publish it to userspace.
> 
> In the case where you add the watchdog device, but then the subsequent
> request_irq() fails, there is a window where the watchdog device could
> be opened and started.  You then fall out through the error paths, and
> the module could be removed.
> 
> Don't do this.  Always setup the device first.  Then publish it.  Never
> the other way around.

Russell was faster in replying, but I would have given the same NAK:
the registering of the watchdog means that userspace get access/control over
the watchdog device. So the request_irq should be done before that.

In your trouble description you wrote: "Probe function of s3c2410 watchdog
calls request_irq before initializing required value (wdt_count)."
Should we not fix the initialization of the wdt_count value instead of the
request_irq? i will have a look at the code somewhere this weekend.

Mvg,
Wim.