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SubjectRe: [PATCHv5 01/10] Thermal: Do kfree in _unregister functions
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On Tue, 2014-01-21 at 11:46 -0800, Dmitry Torokhov wrote:
> Hi Durgadoss,
>
> On Fri, Jan 17, 2014 at 05:26:18AM +0530, Durgadoss R wrote:
> > Currently the thermal_release function does
> > kfree for all devices when they call device_unregister.
> > This makes code scattering i.e whenever we add new
> > devices (to thermal class) we need to add its
> > corresponding kfree in thermal_release function.
> > And the if-else is also growing lengthy.
> >
> > Instead, do all kfree() of devices in their own
> > _unregister functions. This makes the code look
> > clean and easy to maintain.
> >
> > Signed-off-by: Durgadoss R <durgadoss.r@intel.com>
> > ---
> > drivers/thermal/thermal_core.c | 17 +++++------------
> > 1 file changed, 5 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> > index 338a88b..165afc6 100644
> > --- a/drivers/thermal/thermal_core.c
> > +++ b/drivers/thermal/thermal_core.c
> > @@ -1042,18 +1042,7 @@ EXPORT_SYMBOL_GPL(thermal_zone_unbind_cooling_device);
> >
> > static void thermal_release(struct device *dev)
> > {
> > - struct thermal_zone_device *tz;
> > - struct thermal_cooling_device *cdev;
> > -
> > - if (!strncmp(dev_name(dev), "thermal_zone",
> > - sizeof("thermal_zone") - 1)) {
> > - tz = to_thermal_zone(dev);
> > - kfree(tz);
> > - } else if(!strncmp(dev_name(dev), "cooling_device",
> > - sizeof("cooling_device") - 1)){
> > - cdev = to_cooling_device(dev);
> > - kfree(cdev);
> > - }
> > + /* No-op since kfree(dev) is done in _unregister functions */
> > }
> >
> > static struct class thermal_class = {
> > @@ -1146,6 +1135,7 @@ __thermal_cooling_device_register(struct device_node *np,
> > unregister:
> > release_idr(&thermal_cdev_idr, &thermal_idr_lock, cdev->id);
> > device_unregister(&cdev->device);
> > + kfree(cdev);
>
> This is broken, you can not assume that you are holding the last
> reference. Please observe help text of DEBUG_KOBJECT_RELEASE config
> option, activate said option and try unregistering thermal device.
>
agreed.
If you think it is too complicated to support the different thermal
components in thermal_release(), we can introduce per device .release()
callback as well.

thanks,
rui
> Thanks.
>




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