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

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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: ce26c5bb95 ("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>
This commit is contained in:
Kant Fan
2022-10-25 15:21:09 +08:00
committed by Greg Kroah-Hartman
parent 0e945ea733
commit 876c6ab967
3 changed files with 12 additions and 13 deletions
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7
include/linux/devfreq.h
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@@ -149,8 +149,8 @@ struct devfreq_stats {
* @work: delayed work for load monitoring.
* @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
@@ -187,7 +187,8 @@ 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;