linux-kernel - Re: [PATCH v2] thermal: devfreq_cooling: use local ops instead of global ops

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Date:   Wed, 13 Apr 2022 16:58:46 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Lukasz Luba <lukasz.luba@....com>,
        Kant Fan <kant@...winnertech.com>
Cc:     Amit Kucheria <amitk@...nel.org>,
        "Zhang, Rui" <rui.zhang@...el.com>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        allwinner-opensource-support@...winnertech.com,
        Stable <stable@...r.kernel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Ionela Voinescu <ionela.voinescu@....com>
Subject: Re: [PATCH v2] thermal: devfreq_cooling: use local ops instead of
 global ops

On Fri, Mar 25, 2022 at 10:02 AM Lukasz Luba <lukasz.luba@....com> wrote:
>
> Hi Kant,
>
> On 3/25/22 07:30, Kant Fan wrote:
> > Fix access illegal address problem in following condition:
> > There are muti devfreq cooling devices in system, some of them has
> > em model but other does not, energy model ops such as state2power will
> > append to global devfreq_cooling_ops when the cooling device with
> > em model register. It makes the cooling device without em model
> > also use devfreq_cooling_ops after appending when register later by
> > of_devfreq_cooling_register_power() or of_devfreq_cooling_register().
> >
> > IPA governor regards the cooling devices without em model as a power actor
> > because they also have energy model ops, and will access illegal address
> > at dfc->em_pd when execute cdev->ops->get_requested_power,
> > cdev->ops->state2power or cdev->ops->power2state.
> >
> > Fixes: 615510fe13bd2 ("thermal: devfreq_cooling: remove old power model and use EM")
> > Cc: stable@...r.kernel.org # 5.13+
> > Signed-off-by: Kant Fan <kant@...winnertech.com>
> > ---
> >   drivers/thermal/devfreq_cooling.c | 25 ++++++++++++++++++-------
> >   1 file changed, 18 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/thermal/devfreq_cooling.c b/drivers/thermal/devfreq_cooling.c
> > index 4310cb342a9f..d38a80adec73 100644
> > --- a/drivers/thermal/devfreq_cooling.c
> > +++ b/drivers/thermal/devfreq_cooling.c
> > @@ -358,21 +358,28 @@ of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df,
> >       struct thermal_cooling_device *cdev;
> >       struct device *dev = df->dev.parent;
> >       struct devfreq_cooling_device *dfc;
> > +     struct thermal_cooling_device_ops *ops;
> >       char *name;
> >       int err, num_opps;
> >
> > -     dfc = kzalloc(sizeof(*dfc), GFP_KERNEL);
> > -     if (!dfc)
> > +     ops = kmemdup(&devfreq_cooling_ops, sizeof(*ops), GFP_KERNEL);
> > +     if (!ops)
> >               return ERR_PTR(-ENOMEM);
> >
> > +     dfc = kzalloc(sizeof(*dfc), GFP_KERNEL);
> > +     if (!dfc) {
> > +             err = -ENOMEM;
> > +             goto free_ops;
> > +     }
> > +
> >       dfc->devfreq = df;
> >
> >       dfc->em_pd = em_pd_get(dev);
> >       if (dfc->em_pd) {
> > -             devfreq_cooling_ops.get_requested_power =
> > +             ops->get_requested_power =
> >                       devfreq_cooling_get_requested_power;
> > -             devfreq_cooling_ops.state2power = devfreq_cooling_state2power;
> > -             devfreq_cooling_ops.power2state = devfreq_cooling_power2state;
> > +             ops->state2power = devfreq_cooling_state2power;
> > +             ops->power2state = devfreq_cooling_power2state;
> >
> >               dfc->power_ops = dfc_power;
> >
> > @@ -407,8 +414,7 @@ of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df,
> >       if (!name)
> >               goto remove_qos_req;
> >
> > -     cdev = thermal_of_cooling_device_register(np, name, dfc,
> > -                                               &devfreq_cooling_ops);
> > +     cdev = thermal_of_cooling_device_register(np, name, dfc, ops);
> >       kfree(name);
> >
> >       if (IS_ERR(cdev)) {
> > @@ -429,6 +435,8 @@ of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df,
> >       kfree(dfc->freq_table);
> >   free_dfc:
> >       kfree(dfc);
> > +free_ops:
> > +     kfree(ops);
> >
> >       return ERR_PTR(err);
> >   }
> > @@ -510,11 +518,13 @@ EXPORT_SYMBOL_GPL(devfreq_cooling_em_register);
> >   void devfreq_cooling_unregister(struct thermal_cooling_device *cdev)
> >   {
> >       struct devfreq_cooling_device *dfc;
> > +     const struct thermal_cooling_device_ops *ops;
> >       struct device *dev;
> >
> >       if (IS_ERR_OR_NULL(cdev))
> >               return;
> >
> > +     ops = cdev->ops;
> >       dfc = cdev->devdata;
> >       dev = dfc->devfreq->dev.parent;
> >
> > @@ -525,5 +535,6 @@ void devfreq_cooling_unregister(struct thermal_cooling_device *cdev)
> >
> >       kfree(dfc->freq_table);
> >       kfree(dfc);
> > +     kfree(ops);
> >   }
> >   EXPORT_SYMBOL_GPL(devfreq_cooling_unregister);
>
>
> Thank you for updating it, LGTM
>
> Reviewed-by: Lukasz Luba <lukasz.luba@....com>

Applied as 5.19 material.

Lukasz, this had a conflict with your EM series, please double check
if my resolution in the bleeding-edge branch is correct.

Thanks!