drivers/base/power: add dpm_sysfs_change_owner()

Add a helper to change the owner of a device's power entries. This
needs to happen when the ownership of a device is changed, e.g. when
moving network devices between network namespaces.
This function will be used to correctly account for ownership changes,
e.g. when moving network devices between network namespaces.

Reviewed-by: Greg Kroah-Hartman <[e-mail]>
Reviewed-by: "Rafael J. Wysocki" <[e-mail]>
Signed-off-by: Christian Brauner <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/base/core.c

···
 	if (error)
 		goto out;
 
+	error = dpm_sysfs_change_owner(dev, kuid, kgid);
+	if (error)
+		goto out;
+
 #ifdef CONFIG_BLOCK
 	if (sysfs_deprecated && dev->class == &block_class)
 		goto out;

drivers/base/power/power.h

···
 extern void pm_qos_sysfs_remove_flags(struct device *dev);
 extern int pm_qos_sysfs_add_latency_tolerance(struct device *dev);
 extern void pm_qos_sysfs_remove_latency_tolerance(struct device *dev);
+extern int dpm_sysfs_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid);
 
 #else /* CONFIG_PM */
 
···
 
 static inline int dpm_sysfs_add(struct device *dev) { return 0; }
 static inline void dpm_sysfs_remove(struct device *dev) {}
+static inline int dpm_sysfs_change_owner(struct device *dev, kuid_t kuid,
+					 kgid_t kgid) { return 0; }
 
 #endif
 

drivers/base/power/sysfs.c

···
 	return enabled ? sprintf(buf, "%lld\n", msec) : sprintf(buf, "\n");
 }
 
+static inline int dpm_sysfs_wakeup_change_owner(struct device *dev, kuid_t kuid,
+						kgid_t kgid)
+{
+	if (dev->power.wakeup && dev->power.wakeup->dev)
+		return device_change_owner(dev->power.wakeup->dev, kuid, kgid);
+	return 0;
+}
+
 static DEVICE_ATTR_RO(wakeup_last_time_ms);
 
 #ifdef CONFIG_PM_AUTOSLEEP
···
 
 static DEVICE_ATTR_RO(wakeup_prevent_sleep_time_ms);
 #endif /* CONFIG_PM_AUTOSLEEP */
-#endif /* CONFIG_PM_SLEEP */
+#else /* CONFIG_PM_SLEEP */
+static inline int dpm_sysfs_wakeup_change_owner(struct device *dev, kuid_t kuid,
+						kgid_t kgid)
+{
+	return 0;
+}
+#endif
 
 #ifdef CONFIG_PM_ADVANCED_DEBUG
 static ssize_t runtime_usage_show(struct device *dev,
···
  err_out:
 	sysfs_remove_group(&dev->kobj, &pm_attr_group);
 	return rc;
+}
+
+int dpm_sysfs_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid)
+{
+	int rc;
+
+	if (device_pm_not_required(dev))
+		return 0;
+
+	rc = sysfs_group_change_owner(&dev->kobj, &pm_attr_group, kuid, kgid);
+	if (rc)
+		return rc;
+
+	if (pm_runtime_callbacks_present(dev)) {
+		rc = sysfs_group_change_owner(
+			&dev->kobj, &pm_runtime_attr_group, kuid, kgid);
+		if (rc)
+			return rc;
+	}
+
+	if (device_can_wakeup(dev)) {
+		rc = sysfs_group_change_owner(&dev->kobj, &pm_wakeup_attr_group,
+					      kuid, kgid);
+		if (rc)
+			return rc;
+
+		rc = dpm_sysfs_wakeup_change_owner(dev, kuid, kgid);
+		if (rc)
+			return rc;
+	}
+
+	if (dev->power.set_latency_tolerance) {
+		rc = sysfs_group_change_owner(
+			&dev->kobj, &pm_qos_latency_tolerance_attr_group, kuid,
+			kgid);
+		if (rc)
+			return rc;
+	}
+	return 0;
 }
 
 int wakeup_sysfs_add(struct device *dev)