Re: BUG in: Driver core: convert block from raw kobjects to core devices (fwd)

[Kay Sievers <kay.sievers@vrfy.org>]

On Wed, 2007-10-31 at 10:15 -0500, James Bottomley wrote:
> On Wed, 2007-10-31 at 07:32 -0700, Greg KH wrote:
> > Hm, I seem to have missed the part in this thread where someone said
> > that it was valid to have a parent reference a child device.  That's
> > just wrong and needs to be fixed.  Is that in the scsi layer somewhere?
> > The block layer?  It sure isn't in the driver core...
> 
> This is the piece I'm still not clear on.  It's something to do with the
> gendisk.  I'd have to look in block, but I believe the queue takes a ref
> to the gendisk.

Yes, the queue is a child of the disk.

> The scsi_device has a ref to the queue

Yeah, while the queue is a grandchild of the scsi_device with the
unified sysfs layout.

> and the scsi_disk (in sd) has a
> ref to both the scsi_device and the gendisk.  That means, until sd is
> unbound and the scsi_disk released, there's an implied unbreakable
> reference chain.
> 
> at least, I think that's what the problem is.

Yes, sounds right. We need to break that deleted-but-wait-for-cleanup at
least at one of the devices involved.

Thanks,
Kay