Re: [PATCH v2] iio: adc: sun4i-gpadc-iio: fix parent device being used in devm function

[Maxime Ripard <maxime.ripard@free-electrons.com>]

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On Thu, May 18, 2017 at 08:36:07AM +0200, Quentin Schulz wrote:
> For the sake of DT binding stability, this IIO driver is a child of an
> MFD driver for Allwinner A10, A13 and A31 because there already exists a
> DT binding for this IP. The MFD driver has a DT node but the IIO driver
> does not.
> 
> The IIO device registers the temperature sensor in the thermal framework
> using the DT node of the parent, the MFD device, so the thermal
> framework could match the phandle to the MFD device in the DT and the
> struct device used to register in the thermal framework.
> 
> devm_thermal_zone_of_sensor_register was previously used to register the
> thermal sensor with the parent struct device of the IIO device,
> representing the MFD device. By doing so, we registered actually the
> parent in the devm routine and not the actual IIO device.
> 
> This lead to the devm unregister function not being called when the IIO
> module driver is removed. It resulted in the thermal framework still
> polling the get_temp function of the IIO module while the device doesn't
> exist anymore, thus generated a kernel panic.
> 
> Use the non-devm function instead and do the unregister manually in the
> remove function.
> 
> Fixes: d1caa9905538 ("iio: adc: add support for Allwinner SoCs ADC")
> 
> Signed-off-by: Quentin Schulz <quentin.schulz@free-electrons.com>
> Reported-by: Corentin Labbe <clabbe.montjoie@gmail.com>

Reviewed-by: Maxime Ripard <maxime.ripard@free-electrons.com>

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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