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

Dmitry Osipenko
2018-08-13T17:02:57Z

On Monday, 13 August 2018 19:53:33 MSK Viresh Kumar wrote:
> On 13 August 2018 at 22:13, Dmitry Osipenko <digetx@gmail.com> wrote:
> > On Monday, 13 August 2018 19:21:43 MSK Viresh Kumar wrote:
> >> On 13 August 2018 at 21:36, Dmitry Osipenko <digetx@gmail.com> 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 :)

Okay, I'll make the patch. Thank you for the help.