[PATCH v2] devfreq: governor: Add a private governor_data for governors in devfreq

[PATCH v2] devfreq: governor: Add a private governor_data for governors in devfreq

[Kant Fan]

The member void *data in the structure devfreq can be overwrite
by governor_userspace. For example:
1. The device driver assigned the devfreq governor to simple_ondemand
by the function devfreq_add_device() and init the devfreq member
void *data to a pointer of a static structure devfreq_simple_ondemand_data
by the function devfreq_add_device().
2. The user changed the devfreq governor to userspace by the command
"echo userspace > /sys/class/devfreq/.../governor".
3. The governor userspace alloced a dynamic memory for the struct
userspace_data and assigend the member void *data of devfreq to
this memory by the function userspace_init().
4. The user changed the devfreq governor back to simple_ondemand
by the command "echo simple_ondemand > /sys/class/devfreq/.../governor".
5. The governor userspace exited and assigned the member void *data
in the structure devfreq to NULL by the function userspace_exit().
6. The governor simple_ondemand fetched the static information of
devfreq_simple_ondemand_data in the function
devfreq_simple_ondemand_func() but the member void *data of devfreq was
assigned to NULL by the function userspace_exit().
7. The information of upthreshold and downdifferential is lost
and the governor simple_ondemand can't work correctly.

The member void *data in the structure devfreq is designed for
a static pointer used in a governor and inited by the function
devfreq_add_device(). This patch add an element named governor_data
in the devfreq structure which can be used by a governor(E.g userspace)
who want to assign a private data to do some private things.

Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>

Signed-off-by: Kant Fan <kant@allwinnertech.com>
---
 drivers/devfreq/governor_userspace.c | 12 ++++++------
 include/linux/devfreq.h              |  7 ++++---
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/devfreq/governor_userspace.c b/drivers/devfreq/governor_userspace.c
index ab9db7adb3ad..d69672ccacc4 100644
--- a/drivers/devfreq/governor_userspace.c
+++ b/drivers/devfreq/governor_userspace.c
@@ -21,7 +21,7 @@ struct userspace_data {
 
 static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
 {
-	struct userspace_data *data = df->data;
+	struct userspace_data *data = df->governor_data;
 
 	if (data->valid)
 		*freq = data->user_frequency;
@@ -40,7 +40,7 @@ static ssize_t set_freq_store(struct device *dev, struct device_attribute *attr,
 	int err = 0;
 
 	mutex_lock(&devfreq->lock);
-	data = devfreq->data;
+	data = devfreq->governor_data;
 
 	sscanf(buf, "%lu", &wanted);
 	data->user_frequency = wanted;
@@ -60,7 +60,7 @@ static ssize_t set_freq_show(struct device *dev,
 	int err = 0;
 
 	mutex_lock(&devfreq->lock);
-	data = devfreq->data;
+	data = devfreq->governor_data;
 
 	if (data->valid)
 		err = sprintf(buf, "%lu\n", data->user_frequency);
@@ -91,7 +91,7 @@ static int userspace_init(struct devfreq *devfreq)
 		goto out;
 	}
 	data->valid = false;
-	devfreq->data = data;
+	devfreq->governor_data = data;
 
 	err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
 out:
@@ -107,8 +107,8 @@ static void userspace_exit(struct devfreq *devfreq)
 	if (devfreq->dev.kobj.sd)
 		sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
 
-	kfree(devfreq->data);
-	devfreq->data = NULL;
+	kfree(devfreq->governor_data);
+	devfreq->governor_data = NULL;
 }
 
 static int devfreq_userspace_handler(struct devfreq *devfreq,
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index 34aab4dd336c..d265af3fb0a4 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -152,8 +152,8 @@ struct devfreq_stats {
  * @max_state:		count of entry present in the frequency table.
  * @previous_freq:	previously configured frequency value.
  * @last_status:	devfreq user device info, performance statistics
- * @data:	Private data of the governor. The devfreq framework does not
- *		touch this.
+ * @data:	devfreq core pass to governors, governor should not change it.
+ * @governor_data:	private data for governors, devfreq core doesn't touch it.
  * @user_min_freq_req:	PM QoS minimum frequency request from user (via sysfs)
  * @user_max_freq_req:	PM QoS maximum frequency request from user (via sysfs)
  * @scaling_min_freq:	Limit minimum frequency requested by OPP interface
@@ -193,7 +193,8 @@ struct devfreq {
 	unsigned long previous_freq;
 	struct devfreq_dev_status last_status;
 
-	void *data; /* private data for governors */
+	void *data;
+	void *governor_data;
 
 	struct dev_pm_qos_request user_min_freq_req;
 	struct dev_pm_qos_request user_max_freq_req;
-- 
2.29.0

Re: [PATCH v2] devfreq: governor: Add a private governor_data for governors in devfreq

[Chanwoo Choi]

Hi,

I'm sorry for late reply. It looks good to me.
Instead, this patch should contain the 'Fixes' information
with the following commit because the changed code was merged
on the patch[1]. Also, need to send it to stable mailing list.

[1] ce26c5bb9569d8b826f01b8620fc16d8da6821e9
PM / devfreq: Add basic governors

Lastly, I think that need to change the patch title as following:
- PM / devfreq: governor: Add a private governor_data for governor


On 22. 10. 10. 16:22, Kant Fan wrote:
> The member void *data in the structure devfreq can be overwrite
> by governor_userspace. For example:
> 1. The device driver assigned the devfreq governor to simple_ondemand
> by the function devfreq_add_device() and init the devfreq member
> void *data to a pointer of a static structure devfreq_simple_ondemand_data
> by the function devfreq_add_device().
> 2. The user changed the devfreq governor to userspace by the command
> "echo userspace > /sys/class/devfreq/.../governor".
> 3. The governor userspace alloced a dynamic memory for the struct
> userspace_data and assigend the member void *data of devfreq to
> this memory by the function userspace_init().
> 4. The user changed the devfreq governor back to simple_ondemand
> by the command "echo simple_ondemand > /sys/class/devfreq/.../governor".
> 5. The governor userspace exited and assigned the member void *data
> in the structure devfreq to NULL by the function userspace_exit().
> 6. The governor simple_ondemand fetched the static information of
> devfreq_simple_ondemand_data in the function
> devfreq_simple_ondemand_func() but the member void *data of devfreq was
> assigned to NULL by the function userspace_exit().
> 7. The information of upthreshold and downdifferential is lost
> and the governor simple_ondemand can't work correctly.
> 
> The member void *data in the structure devfreq is designed for
> a static pointer used in a governor and inited by the function
> devfreq_add_device(). This patch add an element named governor_data
> in the devfreq structure which can be used by a governor(E.g userspace)
> who want to assign a private data to do some private things.
> 
> Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
> 
> Signed-off-by: Kant Fan <kant@allwinnertech.com>
> ---
>  drivers/devfreq/governor_userspace.c | 12 ++++++------
>  include/linux/devfreq.h              |  7 ++++---
>  2 files changed, 10 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/devfreq/governor_userspace.c b/drivers/devfreq/governor_userspace.c
> index ab9db7adb3ad..d69672ccacc4 100644
> --- a/drivers/devfreq/governor_userspace.c
> +++ b/drivers/devfreq/governor_userspace.c
> @@ -21,7 +21,7 @@ struct userspace_data {
>  
>  static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
>  {
> -	struct userspace_data *data = df->data;
> +	struct userspace_data *data = df->governor_data;
>  
>  	if (data->valid)
>  		*freq = data->user_frequency;
> @@ -40,7 +40,7 @@ static ssize_t set_freq_store(struct device *dev, struct device_attribute *attr,
>  	int err = 0;
>  
>  	mutex_lock(&devfreq->lock);
> -	data = devfreq->data;
> +	data = devfreq->governor_data;
>  
>  	sscanf(buf, "%lu", &wanted);
>  	data->user_frequency = wanted;
> @@ -60,7 +60,7 @@ static ssize_t set_freq_show(struct device *dev,
>  	int err = 0;
>  
>  	mutex_lock(&devfreq->lock);
> -	data = devfreq->data;
> +	data = devfreq->governor_data;
>  
>  	if (data->valid)
>  		err = sprintf(buf, "%lu\n", data->user_frequency);
> @@ -91,7 +91,7 @@ static int userspace_init(struct devfreq *devfreq)
>  		goto out;
>  	}
>  	data->valid = false;
> -	devfreq->data = data;
> +	devfreq->governor_data = data;
>  
>  	err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
>  out:
> @@ -107,8 +107,8 @@ static void userspace_exit(struct devfreq *devfreq)
>  	if (devfreq->dev.kobj.sd)
>  		sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
>  
> -	kfree(devfreq->data);
> -	devfreq->data = NULL;
> +	kfree(devfreq->governor_data);
> +	devfreq->governor_data = NULL;
>  }
>  
>  static int devfreq_userspace_handler(struct devfreq *devfreq,
> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
> index 34aab4dd336c..d265af3fb0a4 100644
> --- a/include/linux/devfreq.h
> +++ b/include/linux/devfreq.h
> @@ -152,8 +152,8 @@ struct devfreq_stats {
>   * @max_state:		count of entry present in the frequency table.
>   * @previous_freq:	previously configured frequency value.
>   * @last_status:	devfreq user device info, performance statistics
> - * @data:	Private data of the governor. The devfreq framework does not
> - *		touch this.
> + * @data:	devfreq core pass to governors, governor should not change it.
> + * @governor_data:	private data for governors, devfreq core doesn't touch it.
>   * @user_min_freq_req:	PM QoS minimum frequency request from user (via sysfs)
>   * @user_max_freq_req:	PM QoS maximum frequency request from user (via sysfs)
>   * @scaling_min_freq:	Limit minimum frequency requested by OPP interface
> @@ -193,7 +193,8 @@ struct devfreq {
>  	unsigned long previous_freq;
>  	struct devfreq_dev_status last_status;
>  
> -	void *data; /* private data for governors */
> +	void *data;
> +	void *governor_data;
>  
>  	struct dev_pm_qos_request user_min_freq_req;
>  	struct dev_pm_qos_request user_max_freq_req;

-- 
Best Regards,
Samsung Electronics
Chanwoo Choi

Re: [PATCH v2] devfreq: governor: Add a private governor_data for governors in devfreq

[Chanwoo Choi]

On 22. 10. 13. 04:00, Chanwoo Choi wrote:
> Hi,
> 
> I'm sorry for late reply. It looks good to me.
> Instead, this patch should contain the 'Fixes' information
> with the following commit because the changed code was merged
> on the patch[1]. Also, need to send it to stable mailing list.
> 
> [1] ce26c5bb9569d8b826f01b8620fc16d8da6821e9
> PM / devfreq: Add basic governors
> 
> Lastly, I think that need to change the patch title as following:
> - PM / devfreq: governor: Add a private governor_data for governor
> 
> 
> On 22. 10. 10. 16:22, Kant Fan wrote:
>> The member void *data in the structure devfreq can be overwrite
>> by governor_userspace. For example:
>> 1. The device driver assigned the devfreq governor to simple_ondemand
>> by the function devfreq_add_device() and init the devfreq member
>> void *data to a pointer of a static structure devfreq_simple_ondemand_data
>> by the function devfreq_add_device().
>> 2. The user changed the devfreq governor to userspace by the command
>> "echo userspace > /sys/class/devfreq/.../governor".
>> 3. The governor userspace alloced a dynamic memory for the struct
>> userspace_data and assigend the member void *data of devfreq to
>> this memory by the function userspace_init().
>> 4. The user changed the devfreq governor back to simple_ondemand
>> by the command "echo simple_ondemand > /sys/class/devfreq/.../governor".
>> 5. The governor userspace exited and assigned the member void *data
>> in the structure devfreq to NULL by the function userspace_exit().
>> 6. The governor simple_ondemand fetched the static information of
>> devfreq_simple_ondemand_data in the function
>> devfreq_simple_ondemand_func() but the member void *data of devfreq was
>> assigned to NULL by the function userspace_exit().
>> 7. The information of upthreshold and downdifferential is lost
>> and the governor simple_ondemand can't work correctly.
>>
>> The member void *data in the structure devfreq is designed for
>> a static pointer used in a governor and inited by the function
>> devfreq_add_device(). This patch add an element named governor_data
>> in the devfreq structure which can be used by a governor(E.g userspace)
>> who want to assign a private data to do some private things.
>>
>> Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
>>
>> Signed-off-by: Kant Fan <kant@allwinnertech.com>
>> ---
>>  drivers/devfreq/governor_userspace.c | 12 ++++++------
>>  include/linux/devfreq.h              |  7 ++++---
>>  2 files changed, 10 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/devfreq/governor_userspace.c b/drivers/devfreq/governor_userspace.c
>> index ab9db7adb3ad..d69672ccacc4 100644
>> --- a/drivers/devfreq/governor_userspace.c
>> +++ b/drivers/devfreq/governor_userspace.c
>> @@ -21,7 +21,7 @@ struct userspace_data {
>>  
>>  static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
>>  {
>> -	struct userspace_data *data = df->data;
>> +	struct userspace_data *data = df->governor_data;
>>  
>>  	if (data->valid)
>>  		*freq = data->user_frequency;
>> @@ -40,7 +40,7 @@ static ssize_t set_freq_store(struct device *dev, struct device_attribute *attr,
>>  	int err = 0;
>>  
>>  	mutex_lock(&devfreq->lock);
>> -	data = devfreq->data;
>> +	data = devfreq->governor_data;
>>  
>>  	sscanf(buf, "%lu", &wanted);
>>  	data->user_frequency = wanted;
>> @@ -60,7 +60,7 @@ static ssize_t set_freq_show(struct device *dev,
>>  	int err = 0;
>>  
>>  	mutex_lock(&devfreq->lock);
>> -	data = devfreq->data;
>> +	data = devfreq->governor_data;
>>  
>>  	if (data->valid)
>>  		err = sprintf(buf, "%lu\n", data->user_frequency);
>> @@ -91,7 +91,7 @@ static int userspace_init(struct devfreq *devfreq)
>>  		goto out;
>>  	}
>>  	data->valid = false;
>> -	devfreq->data = data;
>> +	devfreq->governor_data = data;
>>  
>>  	err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
>>  out:
>> @@ -107,8 +107,8 @@ static void userspace_exit(struct devfreq *devfreq)
>>  	if (devfreq->dev.kobj.sd)
>>  		sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
>>  
>> -	kfree(devfreq->data);
>> -	devfreq->data = NULL;
>> +	kfree(devfreq->governor_data);
>> +	devfreq->governor_data = NULL;
>>  }
>>  
>>  static int devfreq_userspace_handler(struct devfreq *devfreq,
>> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
>> index 34aab4dd336c..d265af3fb0a4 100644
>> --- a/include/linux/devfreq.h
>> +++ b/include/linux/devfreq.h
>> @@ -152,8 +152,8 @@ struct devfreq_stats {
>>   * @max_state:		count of entry present in the frequency table.
>>   * @previous_freq:	previously configured frequency value.
>>   * @last_status:	devfreq user device info, performance statistics
>> - * @data:	Private data of the governor. The devfreq framework does not
>> - *		touch this.
>> + * @data:	devfreq core pass to governors, governor should not change it.

In addition, the devfreq driver pass the 'data' from devfreq driver
to governor by using devfreq_add_device. I think that 'devfreq driver'
is more proper 

* @data:	devfreq driver pass to governors, governor should not change it.

And then, there are extra changes required.

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 63347a5ae599..0c59b7978391 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -776,8 +776,7 @@ static void remove_sysfs_files(struct devfreq *devfreq,
  * @dev:       the device to add devfreq feature.
  * @profile:   device-specific profile to run devfreq.
  * @governor_name:     name of the policy to choose frequency.
- * @data:      private data for the governor. The devfreq framework does not
- *             touch this value.
+ * @data:      devfreq driver pass to governors, governor should not change it.
  */
 struct devfreq *devfreq_add_device(struct device *dev,
                                   struct devfreq_dev_profile *profile,
@@ -1011,8 +1010,7 @@ static void devm_devfreq_dev_release(struct device *dev, void *res)
  * @dev:       the device to add devfreq feature.
  * @profile:   device-specific profile to run devfreq.
  * @governor_name:     name of the policy to choose frequency.
- * @data:      private data for the governor. The devfreq framework does not
- *             touch this value.
+ * @data:      devfreq driver pass to governors, governor should not change it.
  *
  * This function manages automatically the memory of devfreq device using device
  * resource management and simplify the free operation for memory of devfreq

-- 
Best Regards,
Samsung Electronics
Chanwoo Choi

Re: [PATCH v2] devfreq: governor: Add a private governor_data for governors in devfreq

[Kant Fan]

On 10/13/2022 3:19 AM, Chanwoo Choi wrote:
> 
> In addition, the devfreq driver pass the 'data' from devfreq driver
> to governor by using devfreq_add_device. I think that 'devfreq driver'
> is more proper
> 
> * @data:	devfreq driver pass to governors, governor should not change it.
> 
> And then, there are extra changes required.
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 63347a5ae599..0c59b7978391 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -776,8 +776,7 @@ static void remove_sysfs_files(struct devfreq *devfreq,
>    * @dev:       the device to add devfreq feature.
>    * @profile:   device-specific profile to run devfreq.
>    * @governor_name:     name of the policy to choose frequency.
> - * @data:      private data for the governor. The devfreq framework does not
> - *             touch this value.
> + * @data:      devfreq driver pass to governors, governor should not change it.
>    */
>   struct devfreq *devfreq_add_device(struct device *dev,
>                                     struct devfreq_dev_profile *profile,
> @@ -1011,8 +1010,7 @@ static void devm_devfreq_dev_release(struct device *dev, void *res)
>    * @dev:       the device to add devfreq feature.
>    * @profile:   device-specific profile to run devfreq.
>    * @governor_name:     name of the policy to choose frequency.
> - * @data:      private data for the governor. The devfreq framework does not
> - *             touch this value.
> + * @data:      devfreq driver pass to governors, governor should not change it.
>    *
>    * This function manages automatically the memory of devfreq device using device
>    * resource management and simplify the free operation for memory of devfreq
> 

Dear Chanwoo,
Thanks for your kindly advice. I've modified it as patch-v3 [1]. Please 
have a look.

[1] 
https://lore.kernel.org/all/20221014094359.100995-1-kant@allwinnertech.com/

-- 
Best Regards,
Kant Fan