diff mbox series

[RESEND] devfreq: governor: Save void *data in the governor userspace

Message ID 20220329091449.105308-1-kant@allwinnertech.com
State New
Headers show
Series [RESEND] devfreq: governor: Save void *data in the governor userspace | expand

Commit Message

Kant Fan March 29, 2022, 9:14 a.m. UTC
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(). So if a governor want to use void *data
to do some other things, it must save void *data in the init()
function and restore void *data in the exit() function.

Signed-off-by: Kant Fan <kant@allwinnertech.com>
---
 drivers/devfreq/governor_userspace.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Comments

Kant Fan Sept. 14, 2022, 9:15 a.m. UTC | #1
On 3/29/2022 5:14 PM, 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(). So if a governor want to use void *data
> to do some other things, it must save void *data in the init()
> function and restore void *data in the exit() function.
> 
> Signed-off-by: Kant Fan <kant@allwinnertech.com>
> ---
>   drivers/devfreq/governor_userspace.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/devfreq/governor_userspace.c b/drivers/devfreq/governor_userspace.c
> index ab9db7adb3ad..dbbb448dcbcf 100644
> --- a/drivers/devfreq/governor_userspace.c
> +++ b/drivers/devfreq/governor_userspace.c
> @@ -17,6 +17,7 @@
>   struct userspace_data {
>   	unsigned long user_frequency;
>   	bool valid;
> +	void *saved_data;
>   };
>   
>   static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
> @@ -91,6 +92,7 @@ static int userspace_init(struct devfreq *devfreq)
>   		goto out;
>   	}
>   	data->valid = false;
> +	data->saved_data = devfreq->data;
>   	devfreq->data = data;
>   
>   	err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
> @@ -100,6 +102,8 @@ static int userspace_init(struct devfreq *devfreq)
>   
>   static void userspace_exit(struct devfreq *devfreq)
>   {
> +	struct userspace_data *data = devfreq->data;
> +	void *saved_data = data->saved_data;
>   	/*
>   	 * Remove the sysfs entry, unless this is being called after
>   	 * device_del(), which should have done this already via kobject_del().
> @@ -108,7 +112,7 @@ static void userspace_exit(struct devfreq *devfreq)
>   		sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
>   
>   	kfree(devfreq->data);
> -	devfreq->data = NULL;
> +	devfreq->data = saved_data;
>   }
>   
>   static int devfreq_userspace_handler(struct devfreq *devfreq,

Dear MyungJoo, Kyungmin & Chanwoo,
Gently ping this issue... Does this patch has a chance to be accepted?
This seems to be a bug in devfreq userspace governor, which affects the 
switching between governors -- When switching from userspace to 
ondemand, the ondemand governor would be invalid.
If there's any question, please let me know.
Thank you.
MyungJoo Ham Sept. 14, 2022, 9:43 a.m. UTC | #2
>On 3/29/2022 5:14 PM, Kant Fan wrote:
>> The member void *data in the structure devfreq can be overwrite
>> by governor_userspace. 
>> Signed-off-by: Kant Fan <kant@allwinnertech.com>
>> ---
>>   drivers/devfreq/governor_userspace.c | 6 +++++-
>>   1 file changed, 5 insertions(+), 1 deletion(-)
>> 
>> diff --git a/drivers/devfreq/governor_userspace.c b/drivers/devfreq/governor_userspace.c
>> index ab9db7adb3ad..dbbb448dcbcf 100644
>> --- a/drivers/devfreq/governor_userspace.c
>> +++ b/drivers/devfreq/governor_userspace.c
>> @@ -17,6 +17,7 @@
>>   struct userspace_data {
>>           unsigned long user_frequency;
>>           bool valid;
>> +        void *saved_data;
>>   };
>>   
>>   static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
>> @@ -91,6 +92,7 @@ static int userspace_init(struct devfreq *devfreq)
>>                   goto out;
>>           }
>>           data->valid = false;
>> +        data->saved_data = devfreq->data;
>>           devfreq->data = data;
>>   
>>           err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
>> @@ -100,6 +102,8 @@ static int userspace_init(struct devfreq *devfreq)
>>   
>>   static void userspace_exit(struct devfreq *devfreq)
>>   {
>> +        struct userspace_data *data = devfreq->data;
>> +        void *saved_data = data->saved_data;
>>           /*
>>            * Remove the sysfs entry, unless this is being called after
>>            * device_del(), which should have done this already via kobject_del().
>> @@ -108,7 +112,7 @@ static void userspace_exit(struct devfreq *devfreq)
>>                   sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
>>   
>>           kfree(devfreq->data);
>> -        devfreq->data = NULL;
>> +        devfreq->data = saved_data;
>>   }
>>   
>>   static int devfreq_userspace_handler(struct devfreq *devfreq,
>
>Dear MyungJoo, Kyungmin & Chanwoo,
>Gently ping this issue... Does this patch has a chance to be accepted?
>This seems to be a bug in devfreq userspace governor, which affects the 
>switching between governors -- When switching from userspace to 
>ondemand, the ondemand governor would be invalid.
>If there's any question, please let me know.
>Thank you.

Yes, indeed. This is a bug.

Actually, it appears that allocating a new memory buffer for
devfreq->data itself is a bug for a governor, this is supposed
to be allocated by a device driver. Thus, the comment of
"void *data" of "struct devfreq" should be updated:
"/* private data for governors given by device drivers */"

It'd be better to have something like, "void *internal_data"
for governors to freely handle within its context of init-exit,
which is not touched by its users (device drivers).

@Chanwoo: what's your opinion on this?

Cheers,
MyungJoo.
Kant Fan Sept. 15, 2022, 7:41 a.m. UTC | #3
On 9/14/2022 5:43 PM, MyungJoo Ham wrote:
>> On 3/29/2022 5:14 PM, Kant Fan wrote:
>>>   The member void *data in the structure devfreq can be overwrite
>>>   by governor_userspace.
>>>   Signed-off-by: Kant Fan <kant@allwinnertech.com>
>>>   ---
>>>     drivers/devfreq/governor_userspace.c | 6 +++++-
>>>     1 file changed, 5 insertions(+), 1 deletion(-)
>>>   
>>>   diff --git a/drivers/devfreq/governor_userspace.c b/drivers/devfreq/governor_userspace.c
>>>   index ab9db7adb3ad..dbbb448dcbcf 100644
>>>   --- a/drivers/devfreq/governor_userspace.c
>>>   +++ b/drivers/devfreq/governor_userspace.c
>>>   @@ -17,6 +17,7 @@
>>>     struct userspace_data {
>>>             unsigned long user_frequency;
>>>             bool valid;
>>>   +        void *saved_data;
>>>     };
>>>     
>>>     static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
>>>   @@ -91,6 +92,7 @@ static int userspace_init(struct devfreq *devfreq)
>>>                     goto out;
>>>             }
>>>             data->valid = false;
>>>   +        data->saved_data = devfreq->data;
>>>             devfreq->data = data;
>>>     
>>>             err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
>>>   @@ -100,6 +102,8 @@ static int userspace_init(struct devfreq *devfreq)
>>>     
>>>     static void userspace_exit(struct devfreq *devfreq)
>>>     {
>>>   +        struct userspace_data *data = devfreq->data;
>>>   +        void *saved_data = data->saved_data;
>>>             /*
>>>              * Remove the sysfs entry, unless this is being called after
>>>              * device_del(), which should have done this already via kobject_del().
>>>   @@ -108,7 +112,7 @@ static void userspace_exit(struct devfreq *devfreq)
>>>                     sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
>>>     
>>>             kfree(devfreq->data);
>>>   -        devfreq->data = NULL;
>>>   +        devfreq->data = saved_data;
>>>     }
>>>     
>>>     static int devfreq_userspace_handler(struct devfreq *devfreq,
>>
>> Dear MyungJoo, Kyungmin & Chanwoo,
>> Gently ping this issue... Does this patch has a chance to be accepted?
>> This seems to be a bug in devfreq userspace governor, which affects the
>> switching between governors -- When switching from userspace to
>> ondemand, the ondemand governor would be invalid.
>> If there's any question, please let me know.
>> Thank you.
> 
> Yes, indeed. This is a bug.
> 
> Actually, it appears that allocating a new memory buffer for
> devfreq->data itself is a bug for a governor, this is supposed
> to be allocated by a device driver. Thus, the comment of
> "void *data" of "struct devfreq" should be updated:
> "/* private data for governors given by device drivers */"
> 
> It'd be better to have something like, "void *internal_data"
> for governors to freely handle within its context of init-exit,
> which is not touched by its users (device drivers).
> 
> @Chanwoo: what's your opinion on this?
> 
> Cheers,
> MyungJoo.
> 

Hi MyungJoo,
Thanks for your suggestion. Here's the patch-v2, please have a look:

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

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.

Signed-off-by: Kant Fan <kant@allwinnertech.com>
---

diff --git a/drivers/devfreq/governor_userspace.c 
b/drivers/devfreq/governor_userspace.c
index ab9db7a..d69672c 100644
--- a/drivers/devfreq/governor_userspace.c
+++ b/drivers/devfreq/governor_userspace.c
@@ -21,7 +21,7 @@

  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 @@
  	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 @@
  	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 @@
  		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 @@
  	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 34aab4d..d265af3 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -152,8 +152,8 @@
   * @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 @@
  	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;
Kant Fan Sept. 21, 2022, 1:15 p.m. UTC | #4
On 9/15/2022 3:41 PM, Kant Fan wrote:
>>>>     static int devfreq_userspace_handler(struct devfreq *devfreq,
>>>
>>> Dear MyungJoo, Kyungmin & Chanwoo,
>>> Gently ping this issue... Does this patch has a chance to be accepted?
>>> This seems to be a bug in devfreq userspace governor, which affects the
>>> switching between governors -- When switching from userspace to
>>> ondemand, the ondemand governor would be invalid.
>>> If there's any question, please let me know.
>>> Thank you.
>>
>> Yes, indeed. This is a bug.
>>
>> Actually, it appears that allocating a new memory buffer for
>> devfreq->data itself is a bug for a governor, this is supposed
>> to be allocated by a device driver. Thus, the comment of
>> "void *data" of "struct devfreq" should be updated:
>> "/* private data for governors given by device drivers */"
>>
>> It'd be better to have something like, "void *internal_data"
>> for governors to freely handle within its context of init-exit,
>> which is not touched by its users (device drivers).
>>
>> @Chanwoo: what's your opinion on this?
>>
>> Cheers,
>> MyungJoo.
>>
> 
> Hi MyungJoo,
> Thanks for your suggestion. Here's the patch-v2, please have a look:
> 
> -- 
> Subject: [PATCH] devfreq: governor: Add a private governor_data for 
> governors in devfreq
> 
> 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.
> 
> Signed-off-by: Kant Fan <kant@allwinnertech.com>
> ---
> 
> diff --git a/drivers/devfreq/governor_userspace.c 
> b/drivers/devfreq/governor_userspace.c
> index ab9db7a..d69672c 100644
> --- a/drivers/devfreq/governor_userspace.c
> +++ b/drivers/devfreq/governor_userspace.c
> @@ -21,7 +21,7 @@
> 
>   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 @@
>       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 @@
>       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 @@
>           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 @@
>       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 34aab4d..d265af3 100644
> --- a/include/linux/devfreq.h
> +++ b/include/linux/devfreq.h
> @@ -152,8 +152,8 @@
>    * @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 @@
>       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;
> 

Hi MyungJoo,
Sorry to disturb. Just want to say that I'm looking forward to your 
advice on this patch. Thank you :>
MyungJoo Ham Sept. 26, 2022, 9:50 a.m. UTC | #5
> On 9/15/2022 3:41 PM, Kant Fan wrote:
> > 
> > diff --git a/drivers/devfreq/governor_userspace.c 
> > b/drivers/devfreq/governor_userspace.c
> > index ab9db7a..d69672c 100644
> > --- a/drivers/devfreq/governor_userspace.c
> > +++ b/drivers/devfreq/governor_userspace.c
> > @@ -21,7 +21,7 @@
> > 
> >   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 @@
> >       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 @@
> >       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 @@
> >           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 @@
> >       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 34aab4d..d265af3 100644
> > --- a/include/linux/devfreq.h
> > +++ b/include/linux/devfreq.h
> > @@ -152,8 +152,8 @@
> >    * @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 @@
> >       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;
> > 
> 
> Hi MyungJoo,
> Sorry to disturb. Just want to say that I'm looking forward to your 
> advice on this patch. Thank you :>
> 

This new code looks good to me.
Anyway, Chanwoo, how do you think of this?


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


Cheers,
MyungJoo.
diff mbox series

Patch

diff --git a/drivers/devfreq/governor_userspace.c b/drivers/devfreq/governor_userspace.c
index ab9db7adb3ad..dbbb448dcbcf 100644
--- a/drivers/devfreq/governor_userspace.c
+++ b/drivers/devfreq/governor_userspace.c
@@ -17,6 +17,7 @@ 
 struct userspace_data {
 	unsigned long user_frequency;
 	bool valid;
+	void *saved_data;
 };
 
 static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
@@ -91,6 +92,7 @@  static int userspace_init(struct devfreq *devfreq)
 		goto out;
 	}
 	data->valid = false;
+	data->saved_data = devfreq->data;
 	devfreq->data = data;
 
 	err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
@@ -100,6 +102,8 @@  static int userspace_init(struct devfreq *devfreq)
 
 static void userspace_exit(struct devfreq *devfreq)
 {
+	struct userspace_data *data = devfreq->data;
+	void *saved_data = data->saved_data;
 	/*
 	 * Remove the sysfs entry, unless this is being called after
 	 * device_del(), which should have done this already via kobject_del().
@@ -108,7 +112,7 @@  static void userspace_exit(struct devfreq *devfreq)
 		sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
 
 	kfree(devfreq->data);
-	devfreq->data = NULL;
+	devfreq->data = saved_data;
 }
 
 static int devfreq_userspace_handler(struct devfreq *devfreq,