Re: regulator: core: Request GPIO before creating sysfs entries

[Krzysztof Adamski]

On Tue, Feb 23, 2016 at 02:15:21PM +0000, Jon Hunter wrote:
> Hi Krzysztof,
>
> On 23/02/16 13:56, Krzysztof Adamski wrote:
> > On Tue, Feb 23, 2016 at 01:22:38PM +0000, Jon Hunter wrote:
> > > Hi Mark, Krzysztof,
> > >
> > > It appears that commit daad134d6649 ("regulator: core: Request GPIO
> > > before creating sysfs entries") breaks boot on tegra124-nyan-big in
> > > -next today.
> > >
> > > Looking at the change, it does not appear that the exit path has been
> > > updated correctly and so if a regulator is deferred then there is a
> > > crash in the exit path. I am not sure that there is a simple way to
> > > workaround this because of fix from commit 53032dafc6b9 ("regulator
> > > core: fix double-free in regulator_register() error path") unless we
> > > move regulator_ena_gpio_free() into regulator_dev_release().
> >
> > Hi Jon,
> >
> > You are totally right about the problem but I can't see why changing
> > "goto wash" to "goto clean" in error path of regulator_ena_gpio_request
> > is not enough. What am I missing?
>
> So device_unregister() will call regulator_dev_release() which will free
> rdev (see commit 53032dafc6b9). However, rdev is needed by
> regulator_ena_gpio_free() and therefore, we need to call
> regulator_ena_gpio_free() before we call device_unregister(). So
> swapping the order will cause other problems.
>
> One possibility would be to move regulator_ena_gpio_free() into
> regulator_dev_release(). If did we could remove the
> regulator_ena_gpio_free() from regulator_unregister(). However, I have
> not looked at that in great detail. May be Mark can comment if that
> would be ok.

But in case of regulator_ena_gpio_free() failure, we shouldn't call 
device_unregister() at all, since it was not yet registered and that is 
exactly what "clean" does.

Best regards,
Krzysztof Adamski