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

Jon Hunter
2016-02-23T14:15:21Z

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.

Cheers
Jon