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PM / devfreq: use _visible attribute to replace create/remove_sysfs_files()

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Previously, non-generic attributes (polling_interval, timer) used separate
create/delete logic, leading to race conditions during concurrent access in
creation/deletion. Multi-threaded operations also caused inconsistencies
between governor capabilities and attribute states.

1.Use is_visible + sysfs_update_group() to unify management of these
attributes, eliminating creation/deletion races.
2.Add locks and validation to these attributes, ensuring consistency
between current governor capabilities and attribute operations in
multi-threaded environments.

Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Jie Zhan <zhanjie9@hisilicon.com>
Signed-off-by: Pengjie Zhang <zhangpengjie2@huawei.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Link: https://www.spinics.net/lists/kernel/msg5967745.html
This commit is contained in:
Pengjie Zhang
2025-12-16 11:11:53 +08:00
committed by Chanwoo Choi
parent 82bb8dc953
commit 943a872fe4
1 changed files with 60 additions and 43 deletions
Download Patch File Download Diff File Expand all files Collapse all files

103
drivers/devfreq/devfreq.c
View File

@@ -38,6 +38,7 @@
static struct class *devfreq_class;
static struct dentry *devfreq_debugfs;
static const struct attribute_group gov_attr_group;
/*
* devfreq core provides delayed work based load monitoring helper
@@ -784,11 +785,6 @@ static void devfreq_dev_release(struct device *dev)
kfree(devfreq);
}
static void create_sysfs_files(struct devfreq *devfreq,
const struct devfreq_governor *gov);
static void remove_sysfs_files(struct devfreq *devfreq,
const struct devfreq_governor *gov);
/**
* devfreq_add_device() - Add devfreq feature to the device
* @dev: the device to add devfreq feature.
@@ -955,7 +951,10 @@ struct devfreq *devfreq_add_device(struct device *dev,
__func__);
goto err_init;
}
create_sysfs_files(devfreq, devfreq->governor);
err = sysfs_update_group(&devfreq->dev.kobj, &gov_attr_group);
if (err)
goto err_init;
list_add(&devfreq->node, &devfreq_list);
@@ -994,12 +993,9 @@ int devfreq_remove_device(struct devfreq *devfreq)
devfreq_cooling_unregister(devfreq->cdev);
if (devfreq->governor) {
if (devfreq->governor)
devfreq->governor->event_handler(devfreq,
DEVFREQ_GOV_STOP, NULL);
remove_sysfs_files(devfreq, devfreq->governor);
}
device_unregister(&devfreq->dev);
return 0;
@@ -1459,7 +1455,6 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
__func__, df->governor->name, ret);
goto out;
}
remove_sysfs_files(df, df->governor);
/*
* Start the new governor and create the specific sysfs files
@@ -1488,7 +1483,7 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
* Create the sysfs files for the new governor. But if failed to start
* the new governor, restore the sysfs files of previous governor.
*/
create_sysfs_files(df, df->governor);
ret = sysfs_update_group(&df->dev.kobj, &gov_attr_group);
out:
mutex_unlock(&devfreq_list_lock);
@@ -1806,14 +1801,17 @@ static struct attribute *devfreq_attrs[] = {
&dev_attr_trans_stat.attr,
NULL,
};
ATTRIBUTE_GROUPS(devfreq);
static ssize_t polling_interval_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct devfreq *df = to_devfreq(dev);
if (!df->profile)
/* Protect against race between sysfs attrs update and read/write */
guard(mutex)(&devfreq_list_lock);
if (!df->profile || !df->governor ||
!IS_SUPPORTED_ATTR(df->governor->attrs, POLLING_INTERVAL))
return -EINVAL;
return sprintf(buf, "%d\n", df->profile->polling_ms);
@@ -1827,7 +1825,10 @@ static ssize_t polling_interval_store(struct device *dev,
unsigned int value;
int ret;
if (!df->governor)
guard(mutex)(&devfreq_list_lock);
if (!df->governor ||
!IS_SUPPORTED_ATTR(df->governor->attrs, POLLING_INTERVAL))
return -EINVAL;
ret = sscanf(buf, "%u", &value);
@@ -1846,7 +1847,10 @@ static ssize_t timer_show(struct device *dev,
{
struct devfreq *df = to_devfreq(dev);
if (!df->profile)
guard(mutex)(&devfreq_list_lock);
if (!df->profile || !df->governor ||
!IS_SUPPORTED_ATTR(df->governor->attrs, TIMER))
return -EINVAL;
return sprintf(buf, "%s\n", timer_name[df->profile->timer]);
@@ -1860,7 +1864,10 @@ static ssize_t timer_store(struct device *dev, struct device_attribute *attr,
int timer = -1;
int ret = 0, i;
if (!df->governor || !df->profile)
guard(mutex)(&devfreq_list_lock);
if (!df->governor || !df->profile ||
!IS_SUPPORTED_ATTR(df->governor->attrs, TIMER))
return -EINVAL;
ret = sscanf(buf, "%16s", str_timer);
@@ -1904,36 +1911,46 @@ out:
}
static DEVICE_ATTR_RW(timer);
#define CREATE_SYSFS_FILE(df, name) \
{ \
int ret; \
ret = sysfs_create_file(&df->dev.kobj, &dev_attr_##name.attr); \
if (ret < 0) { \
dev_warn(&df->dev, \
"Unable to create attr(%s)\n", "##name"); \
} \
} \
static struct attribute *governor_attrs[] = {
&dev_attr_polling_interval.attr,
&dev_attr_timer.attr,
NULL
};
/* Create the specific sysfs files which depend on each governor. */
static void create_sysfs_files(struct devfreq *devfreq,
const struct devfreq_governor *gov)
static umode_t gov_attr_visible(struct kobject *kobj,
struct attribute *attr, int n)
{
if (IS_SUPPORTED_ATTR(gov->attrs, POLLING_INTERVAL))
CREATE_SYSFS_FILE(devfreq, polling_interval);
if (IS_SUPPORTED_ATTR(gov->attrs, TIMER))
CREATE_SYSFS_FILE(devfreq, timer);
struct device *dev = kobj_to_dev(kobj);
struct devfreq *df = to_devfreq(dev);
if (!df->governor || !df->governor->attrs)
return 0;
if (attr == &dev_attr_polling_interval.attr &&
IS_SUPPORTED_ATTR(df->governor->attrs, POLLING_INTERVAL))
return attr->mode;
if (attr == &dev_attr_timer.attr &&
IS_SUPPORTED_ATTR(df->governor->attrs, TIMER))
return attr->mode;
return 0;
}
/* Remove the specific sysfs files which depend on each governor. */
static void remove_sysfs_files(struct devfreq *devfreq,
const struct devfreq_governor *gov)
{
if (IS_SUPPORTED_ATTR(gov->attrs, POLLING_INTERVAL))
sysfs_remove_file(&devfreq->dev.kobj,
&dev_attr_polling_interval.attr);
if (IS_SUPPORTED_ATTR(gov->attrs, TIMER))
sysfs_remove_file(&devfreq->dev.kobj, &dev_attr_timer.attr);
}
static const struct attribute_group devfreq_group = {
.attrs = devfreq_attrs,
};
static const struct attribute_group gov_attr_group = {
.attrs = governor_attrs,
.is_visible = gov_attr_visible,
};
static const struct attribute_group *devfreq_groups[] = {
&devfreq_group,
&gov_attr_group,
NULL
};
/**
* devfreq_summary_show() - Show the summary of the devfreq devices