Re: [PATCH v1 3/7] powercap/dtpm: Fixup kfree for virtual node

[Daniel Lezcano]

On 16/02/2022 17:22, Ulf Hansson wrote:
> On Sun, 30 Jan 2022 at 22:02, Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> wrote:
> > When the node is virtual there is no release function associated which
> > can free the memory.
> >
> > Free the memory when no 'ops' exists.
> >
> > Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
> > ---
> >   drivers/powercap/dtpm.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/powercap/dtpm.c b/drivers/powercap/dtpm.c
> > index 0b0121c37a1b..7bddd25a6767 100644
> > --- a/drivers/powercap/dtpm.c
> > +++ b/drivers/powercap/dtpm.c
> > @@ -181,12 +181,12 @@ int dtpm_release_zone(struct powercap_zone *pcz)
> >
> >          if (dtpm->ops)
> >                  dtpm->ops->release(dtpm);
> > +       else
> > +               kfree(dtpm);
>
> This doesn't look correct. Below you check dtpm against "root", which
> may be after its memory has been freed.
>
> If the ->release() function should be responsible for freeing the
> dtpm, it needs to be called after the check below.

It is harmless, 'root' is not dereferenced but used as an ID

Moreover, in the patch 5/7 it is moved out this function.


> >          if (root == dtpm)
> >                  root = NULL;
> >
> > -       kfree(dtpm);
> > -
> >          return 0;
> >   }
>
> Kind regards
> Uffe


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