PM/devfreq: governor: Add a private governor_data for governor

commit 5fdded8448924e3631d466eea499b11606c43640 upstream.

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: ce26c5bb9569 ("PM / devfreq: Add basic governors")
Cc: stable@vger.kernel.org # 5.10+
Reviewed-by: Chanwoo Choi <cwchoi00@gmail.com>
Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kant Fan <kant@allwinnertech.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 63347a5..8c5f6f7 100644 (file)
--- 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

diff --git a/drivers/devfreq/governor_userspace.c b/drivers/devfreq/governor_userspace.c
index ab9db7a..d69672c 100644 (file)
--- 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 34aab4d..4dc7cda 100644 (file)
--- 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 driver 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;