Re: [PATCH v4 07/18] PM: EM: Refactor struct em_perf_domain and add default_table

[Lukasz Luba]

On 9/26/23 19:52, Rafael J. Wysocki wrote:
> On Mon, Sep 25, 2023 at 10:11 AM Lukasz Luba <lukasz.luba@xxxxxxx> wrote:
> > The Energy Model is going to support runtime modifications. Refactor old
> > implementation which accessed struct em_perf_state and introduce
> > em_perf_domain::default_table to clean up the design. This new field
> > will help to better distinguish 2 performance state tables.
> >
> > Update all drivers or frameworks which used the old field:
> > em_perf_domain::table and now should use em_perf_domain::default_table.
> >
> > Signed-off-by: Lukasz Luba <lukasz.luba@xxxxxxx>

[snip]

> > diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
> > index 8069f526c9d8..d236e08e80dc 100644
> > --- a/include/linux/energy_model.h
> > +++ b/include/linux/energy_model.h
> > @@ -36,9 +36,19 @@ struct em_perf_state {
> >    */
> >   #define EM_PERF_STATE_INEFFICIENT BIT(0)
> >
> > +/**
> > + * struct em_perf_table - Performance states table
> > + * @state:     List of performance states, in ascending order
> > + * @rcu:       RCU used for safe access and destruction
> > + */
> > +struct em_perf_table {
> > +       struct em_perf_state *state;
> > +       struct rcu_head rcu;
>
> There is no explanation of the role of this rcu_head in the changelog
> or anywhere in this patch.
>
> It is also not used as of this patch AFAICS.
>
> It would be better to add it when it actually gets used IMV.

That's a good point. I will introduce this 'rcu' field later.