Re: [PATCH V5] thermal: Add cooling device's statistics in sysfs

[Viresh Kumar]

On 13 August 2018 at 22:13, Dmitry Osipenko <digetx@xxxxxxxxx> wrote:
> On Monday, 13 August 2018 19:21:43 MSK Viresh Kumar wrote:
>> On 13 August 2018 at 21:36, Dmitry Osipenko <digetx@xxxxxxxxx> wrote:
>> > I'm working on adding support of OPP and cooling for NVIDIA Tegra20/30
>> > CPUFreq driver and stumbled upon a bug that is introduced by this patch.
>> > It is triggered on the driver module unload.
>> The problem is that device_unregister() will end up freeing the cdev as
>> well, so the current sequence is surely wrong.
>>
>> > diff --git a/drivers/thermal/thermal_core.c
>> > b/drivers/thermal/thermal_core.c index 6ab982309e6a..de53c821a282 100644
>> > --- a/drivers/thermal/thermal_core.c
>> > +++ b/drivers/thermal/thermal_core.c
>> > @@ -1102,8 +1102,8 @@ void thermal_cooling_device_unregister(struct
>> > thermal_cooling_device *cdev)>
>> >         mutex_unlock(&thermal_list_lock);
>> >
>> >         ida_simple_remove(&thermal_cdev_ida, cdev->id);
>> >
>> > -       device_unregister(&cdev->device);
>> >
>> >         thermal_cooling_device_destroy_sysfs(cdev);
>> >
>> > +       device_unregister(&cdev->device);
>>
>> But this looks wrong as well, as the device is still around while
>> memory of its sysfs data is gone.
>
> Indeed.
>
>> Maybe something like this is what we need:
>>
>> device_del();
>> thermal_cooling_device_destroy_sysfs();
>> device_put();
>
> [I just realized that thermal_zone and cooling_device are not interrelated.
> I'm not familiar with the thermal/ code]
>
> Thank you Viresh, your proposal looks good to me and works fine. Will you make
> a proper patch?

Maybe you send a patch for this and take the credit as well :)