Messages in this thread Patch in this message | | | From | Kant Fan <> | Subject | [RESEND] devfreq: governor: Save void *data in the governor userspace | Date | Tue, 29 Mar 2022 17:14:49 +0800 |
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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, -- 2.29.0
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