Re: [PATCH V3 2/3] thermal/drivers/cpu_cooling: Unregister with the policy

From: Daniel Lezcano
Date: Wed Jun 26 2019 - 06:20:01 EST


On 26/06/2019 11:06, Rafael J. Wysocki wrote:
> On Wed, Jun 26, 2019 at 8:37 AM Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
>>
>> On 26-06-19, 08:02, Daniel Lezcano wrote:
>>> On 26/06/2019 04:58, Viresh Kumar wrote:
>>>> On 25-06-19, 13:32, Daniel Lezcano wrote:
>>>>> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
>>>>> index aee024e42618..f07454249fbc 100644
>>>>> --- a/drivers/cpufreq/cpufreq.c
>>>>> +++ b/drivers/cpufreq/cpufreq.c
>>>>> @@ -1379,8 +1379,8 @@ static int cpufreq_online(unsigned int cpu)
>>>>> cpufreq_driver->ready(policy);
>>>>>
>>>>> if (cpufreq_thermal_control_enabled(cpufreq_driver))
>>>>> - policy->cdev = of_cpufreq_cooling_register(policy);
>>>>> -
>>>>> + of_cpufreq_cooling_register(policy);
>>>>> +
>>>>
>>>> We don't need any error checking here anymore ?
>>>
>>> There was no error checking initially. This comment and the others below
>>> are for an additional patch IMO, not a change in this one.
>>
>> right, but ...
>>
>>>>> -void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
>>>>> +void cpufreq_cooling_unregister(struct cpufreq_policy *policy)
>>>>> {
>>>>> struct cpufreq_cooling_device *cpufreq_cdev;
>>>>> bool last;
>>>>>
>>>>> - if (!cdev)
>>>>> - return;
>>
>> we used to return without any errors from here. Now we will have
>> problems if regsitering fails for some reason.
>
> Specifically, the last cpufreq_cdev in the list will be unregistered
> AFAICS, and without removing it from the list for that matter, which
> isn't what the caller wants.

Indeed,

What about the resulting code above:

void __cpufreq_cooling_unregister(struct cpufreq_cooling_device
*cpufreq_cdev, int last)
{
/* Unregister the notifier for the last cpufreq cooling device */
if (last)
cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
CPUFREQ_POLICY_NOTIFIER);

thermal_cooling_device_unregister(cpufreq_cdev->cdev);
ida_simple_remove(&cpufreq_ida, cpufreq_cdev->id);
kfree(cpufreq_cdev->idle_time);
kfree(cpufreq_cdev);
}

/**

* cpufreq_cooling_unregister - function to remove cpufreq cooling
device.
* @cdev: thermal cooling device pointer.

*

* This interface function unregisters the "thermal-cpufreq-%x" cooling
device.
*/
void cpufreq_cooling_unregister(struct cpufreq_policy *policy)
{
struct cpufreq_cooling_device *cpufreq_cdev;
bool last;

mutex_lock(&cooling_list_lock);
list_for_each_entry(cpufreq_cdev, &cpufreq_cdev_list, node) {
if (cpufreq_cdev->policy == policy) {
list_del(&cpufreq_cdev->node);
last = list_empty(&cpufreq_cdev_list);
break;
}
}
mutex_unlock(&cooling_list_lock);

if (cpufreq_cdev->policy == policy)
__cpufreq_cooling_unregister(cpufreq_cdev, last);
}
EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);




--
<http://www.linaro.org/> Linaro.org â Open source software for ARM SoCs

Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |
<http://www.linaro.org/linaro-blog/> Blog