Re: [PATCH v2] gpiolib: Fix triggering "kobject: 'gpiochipX' is not initialized, yet" kobject_get() errors

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 4/2/24 6:51 PM, Andy Shevchenko wrote:
> On Tue, Apr 2, 2024 at 7:43 PM Hans de Goede <hdegoede@redhat.com> wrote:
>>
>> When a gpiochip gets added by loading a module, then another driver may
>> be waiting for that gpiochip to load on the deferred-probe list.
>>
>> If the deferred-probe for the consumer of gpiochip then triggers between
>> the gpiodev_add_to_list_unlocked() calls which makes gpio_device_find()
>> see the chip and the gpiochip_setup_dev() later then gpio_device_find()
>> does a kobject_get() on an uninitialzed kobject since the kobject is
> 
> uninitialized

Bartosz, can you fix this up while merging or do you prefer a v3?


>> initialized by gpiochip_setup_dev() calling device_initialize():
>>
>>  arizona spi-10WM5102:00: cannot find GPIO chip arizona, deferring
>>  arizona spi-10WM5102:00: cannot find GPIO chip arizona, deferring
>>  ------------[ cut here ]------------
>>  kobject: 'gpiochip5' (00000000241466f2): is not initialized, yet kobject_get() is being called.
>>  WARNING: CPU: 3 PID: 42 at lib/kobject.c:640 kobject_get+0x43/0x70
>>  Call Trace:
>>   kobject_get
>>   gpio_device_find
>>   gpiod_find_and_request
>>   gpiod_get
>>   snd_byt_wm5102_mc_probe
>>
>> Not only is the device not initialized yet, but when the gpio-device is
>> added to the list things like the irqchip also have not been initialized
>> yet.
>>
>> So gpio_device_find() should really ignore the gpio-device until
>> gpiochip_add_data_with_key() is fully done. Add a device_is_registered()
>> check to gpio_device_find() to ignore gpio-devices on the list which are
>> not yet fully initialized.
> 
> Reviewed-by: Andy Shevchenko <andy@kernel.org>

Thank you for the review.

Regards,

Hans