On Tue, 2020-11-17 at 09:57 +0100, Daniel Lezcano wrote:
> On 17/11/2020 08:18, Zhang Rui wrote:
> > On Mon, 2020-11-16 at 21:59 +0530, Mukesh Ojha wrote:
> > > Cooling stats variable inside
> > > thermal_cooling_device_stats_update()
> > > can get NULL. We should add a NULL check on stat inside for
> > > sanity.
> > >
> > > Signed-off-by: Mukesh Ojha <mo...@codeaurora.org>
> > > ---
> > > drivers/thermal/thermal_sysfs.c | 3 +++
> > > 1 file changed, 3 insertions(+)
> > >
> > > diff --git a/drivers/thermal/thermal_sysfs.c
> > > b/drivers/thermal/thermal_sysfs.c
> > > index a6f371f..f52708f 100644
> > > --- a/drivers/thermal/thermal_sysfs.c
> > > +++ b/drivers/thermal/thermal_sysfs.c
> > > @@ -754,6 +754,9 @@ void
> > > thermal_cooling_device_stats_update(struct
> > > thermal_cooling_device *cdev,
> > > {
> > > struct cooling_dev_stats *stats = cdev->stats;
> > >
> > > + if (!stats)
> > > + return;
> > > +
> >
> > May I know in which case stats can be NULL?
> > The only possibility I can see is that cdev->ops->get_max_state()
> > fails
> > in cooling_device_stats_setup(), right?
>
> A few lines below, the allocation could fail.
>
> stats = kzalloc(var, GFP_KERNEL);
> if (!stats)
> return;
>
> Some drivers define themselves as a cooling device state to let the
> userspace to act on their power. The screen brightness is one example
> with a cdev with 1024 states, the resulting stats table to be
> allocated
> is very big and the kzalloc is prone to fail.
>
Oh, right.
As we're not going to fix the cdev, so I think we do need this patch,
right?
thanks,
rui
> > thanks,
> > rui
> >
> > > spin_lock(&stats->lock);
> > >
> > > if (stats->state == new_state)
>
>
