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

[Lukasz Luba <lukasz.luba@arm.com>]

On 4/13/22 16:06, Lukasz Luba wrote:
> 
> 
> On 4/13/22 15:58, Rafael J. Wysocki wrote:
>> On Fri, Mar 25, 2022 at 10:02 AM Lukasz Luba <lukasz.luba@arm.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@vger.kernel.org # 5.13+
>>>> Signed-off-by: Kant Fan <kant@allwinnertech.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@arm.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.
> 
> OK, I'll let you know after I fetch and build that branch.

I've read the code and confirm you've do this correctly.
I've also built that branch with ENERGY_MODEL and DEVFREQ_COOLING
configs set - no issues observed.
Later this week I would use it for some other development
so I will test it as well.

Thank you for solving this!

Regards,
Lukasz