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Commit b9275d8a authored by Kant Fan's avatar Kant Fan Committed by Greg Kroah-Hartman
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PM/devfreq: governor: Add a private governor_data for governor 



[ Upstream commit 5fdded8448924e3631d466eea499b11606c43640 ]

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.

Fixes: ce26c5bb ("PM / devfreq: Add basic governors")
Cc: stable@vger.kernel.org # 5.10+
Reviewed-by: default avatarChanwoo Choi <cwchoi00@gmail.com>
Acked-by: default avatarMyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: default avatarKant Fan <kant@allwinnertech.com>
Signed-off-by: default avatarChanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 839f3ca8

drivers/devfreq/devfreq.c

+2 −4
Original line number Diff line number Diff line
@@ -603,8 +603,7 @@ static void devfreq_dev_release(struct device *dev) 
 * @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,
@@ -788,8 +787,7 @@ 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

drivers/devfreq/governor_userspace.c

+6 −6
Original line number Diff line number Diff line
@@ -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 store_freq(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 show_freq(struct device *dev, struct device_attribute *attr, 
	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,

include/linux/devfreq.h

+6 −5
Original line number Diff line number Diff line
@@ -121,8 +121,8 @@ struct devfreq_dev_profile { 
 *		devfreq.nb to the corresponding register notifier call chain.

 * @work:	delayed work for load monitoring.

 * @previous_freq:	previously configured frequency value.

 * @data:	Private data of the governor. The devfreq framework does not

 *		touch this.

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

 * @governor_data:	private data for governors, devfreq core doesn't touch it.

 * @min_freq:   Limit minimum frequency requested by user (0: none)

 * @max_freq:   Limit maximum frequency requested by user (0: none)

 * @scaling_min_freq:	Limit minimum frequency requested by OPP interface
@@ -159,7 +159,8 @@ struct devfreq { 
	unsigned long previous_freq;

	struct devfreq_dev_status last_status;



	void *data; /* private data for governors */

	void *data;

	void *governor_data;



	unsigned long min_freq;

	unsigned long max_freq;