Re: [PATCH v2 1/2] thermal: core: Reference count the zone in thermal_zone_get_by_id()

[Lukasz Luba]

On 10/4/24 14:48, Rafael J. Wysocki wrote:
> On Fri, Oct 4, 2024 at 3:43 PM Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote:
> > On Fri, Oct 4, 2024 at 3:37 PM Lukasz Luba <lukasz.luba@xxxxxxx> wrote:
> > > On 10/4/24 14:25, Rafael J. Wysocki wrote:
> > > > Hi Łukasz,
> > > >
> > > > On Fri, Oct 4, 2024 at 10:01 AM Lukasz Luba <lukasz.luba@xxxxxxx> wrote:
> > > > > Hi Rafael,
> > > > >
> > > > > On 10/3/24 13:25, Rafael J. Wysocki wrote:
> > > > > > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

[snip]

> > > > > >
> > > > >
> > > > > I wasn't aware of that helpers in cleanup.h.
> > > > >
> > > > > Could you help me to understand when this this
> > > > > 'if (_T) put_device((&_T->device)' will be called?
> > > >
> > > > When the pointer variable initialized via the CLASS() macro goes out
> > > > of scope (that is, before freeing the memory occupied by the pointer
> > > > itself).
> > >
> > >
> > > OK, so do we still need the old code in
> > > thermal_zone_device_unregister(), which calls
> > > put_device(&tz->device) ?
> >
> > Yes, we do.
> >
> > > Maybe that code can go away?
> >
> > That particular one drops the reference acquired by device_register()
> > and I don't see an alternative clean way to drop it.
>
> The problem there is that local variable tz goes out of scope at the
> end of the function (at least formally) and put_device(&tz->device)
> needs to be called before the wait_for_completion(&tz->removal) which
> definitely needs tz to be still around.

OK, I see now. That makes sense. With that feel free to add:

Reviewed-by: Lukasz Luba <lukasz.luba@xxxxxxx>