Re: [PATCH 1/3] thermal: cpufreq_cooling: Use a copy of local ops for each cooling device

[Lukasz Luba]

On 6/13/22 11:53, Viresh Kumar wrote:
> On 13-06-22, 11:37, Lukasz Luba wrote:
> > Hi Viresh,
> >
> > Thank you for the ACKs in the other patches and suggestion in this one.
> >
> > On 6/13/22 10:16, Viresh Kumar wrote:
> > > On 10-06-22, 11:03, Lukasz Luba wrote:
> > > > It is very unlikely that one CPU cluster would have the EM and some other
> > > > won't have it (because EM registration failed or DT lacks needed entry).
> > > > Although, we should avoid modifying global variable with callbacks anyway.
> > > > Redesign this and add safety for such situation.
> > > >
> > > > Signed-off-by: Lukasz Luba <lukasz.luba@xxxxxxx>
> > > > ---
> > > >    drivers/thermal/cpufreq_cooling.c | 16 +++++++++++++---
> > > >    1 file changed, 13 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/drivers/thermal/cpufreq_cooling.c b/drivers/thermal/cpufreq_cooling.c
> > > > index b8151d95a806..e33183785fac 100644
> > > > --- a/drivers/thermal/cpufreq_cooling.c
> > > > +++ b/drivers/thermal/cpufreq_cooling.c
> > > > @@ -554,7 +554,12 @@ __cpufreq_cooling_register(struct device_node *np,
> > > >    	/* max_level is an index, not a counter */
> > > >    	cpufreq_cdev->max_level = i - 1;
> > > > -	cooling_ops = &cpufreq_cooling_ops;
> > > > +	cooling_ops = kmemdup(&cpufreq_cooling_ops, sizeof(*cooling_ops),
> > > > +			      GFP_KERNEL);
> > >
> > > I don't like the way we are duplicating the ops here. Instead of this it would
> > > be better to add the OPs field in the cooling device structure and fill its
> > > fields from here. The ops structure will be allocated with the cooling device
> > > itself.
> >
> > I think I know what you mean. Make sense. There are quite a few
> > different cooling types of devices which are using the API
> > thermal_of_cooling_device_register() with the custom 'ops'. We
> > probably don't want to disturb that well working drivers and ecosystem.
>
> I was just suggesting to update "struct cpufreq_cooling_device" :)
>
> This is what I was, wrongly, referring to as cooling device.
>
> I should have written the exact structure name instead, my bad.

No worries. Thanks, I'll send a v2 with these changes.