Re: [PATCH] PM / devfreq: Don't delete sysfs group twice

[Chris Diamand <chris.diamand@arm.com>]

Hi!

> As you mentioned, it is right to remain this code in _remove_devfreq()
> for other case to unregister devfreq device except for devfreq_remove_device().

Sure, I'll send out another patch with a comment.

Although, if anyone does unregister devfreq without devfreq_remove_device(),
the userspace governor will still be broken.

I wonder if it would be better to fix this in the governor instead, because
this problem only affects things using sysfs entries. Something like this:

--- a/drivers/devfreq/governor_userspace.c
+++ b/drivers/devfreq/governor_userspace.c
@@ -112,7 +112,13 @@ out:
 
 static void userspace_exit(struct devfreq *devfreq)
 {
-	sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
+	/*
+	 * Remove the sysfs entry, unless this is being called after
+	 * device_del(), which should have done this already via kobject_del().
+	 */
+	if (devfreq->dev.kobj.sd)
+		sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
+
 	kfree(devfreq->data);
 	devfreq->data = NULL;
 }

It's a bit uglier, but would fix it in all cases - what do you think?

Cheers,
Chris