[PATCH] Driver core: fix refcounting bug

Alan Stern
2007-01-08T16:06:46Z

This patch (as832) fixes a newly-introduced bug in the driver core.
When a kobject is assigned to a kset, it must acquire a reference to
the kset.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>

---

The bug was introduced in Kay's "unify /sys/class and /sys/bus at
/sys/subsystem" patch.

I left the assignment of class_dev->kobj.parent as it was, although it is
not needed. The following call to kobject_add() will end up doing the
same thing.

Alan Stern

P.S.: Tracking down refcounting bugs is a real pain! I spent an entire
afternoon on this one... :-(

Index: usb-2.6/drivers/base/class.c
===================================================================
--- usb-2.6.orig/drivers/base/class.c
+++ usb-2.6/drivers/base/class.c
@@ -648,7 +648,7 @@ int class_device_add(struct class_device
class_dev->kobj.parent = &parent_class_dev->kobj;
else {
/* assign parent kset for uevent hook */
- class_dev->kobj.kset = &parent_class->devices_dir;
+ class_dev->kobj.kset = kset_get(&parent_class->devices_dir);
/* the device directory in /sys/subsystem/<name>/devices */
class_dev->kobj.parent = &parent_class->devices_dir.kobj;
}