Re: [PATCH] Driver core: fix refcounting bug

Greg KH
2007-01-09T07:13:58Z

On Mon, Jan 08, 2007 at 08:23:59PM -0800, Andrew Morton wrote:
> On Mon, 8 Jan 2007 11:06:44 -0500 (EST)
> Alan Stern <stern@rowland.harvard.edu> wrote:
>
> > 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;
> > }
>
> OK, I give up. What kernel is this against?

I think this is against my private tree, with the "driver-class" patches
that are not in -mm (for good reason at this point in time.) Right
Alan?

thanks,

greg k-h