Hi Kay,

> > > > > But userspace should also find out about this change, and this patch
> > > > > prevents that from happening.  What about just tearing down the class
> > > > > device and creating a new one?  That way userspace knows about the new
> > > > > linkage properly, and any device naming and permission issues can be
> > > > > handled anew?
> > > > 
> > > > This won't work for Bluetooth. We create the TTY and its class device
> > > > with tty_register_device() and then the device node is present. Then at
> > > > some point later we open that device and the Bluetooth connection gets
> > > > established. Only when the connection has been established we know the
> > > > device that represents it. So tearing down the class device and creating
> > > > a new one will screw up the application that is using this device node.
> > > > 
> > > > Would reissuing the uevent of the class device help here?
> > > 
> > > How about KOBJ_ONLINE/OFFLINE?
> > 
> > I am not that familiar with the internals of kobject. Can you give me an
> > example on how to do that?
> 
> Just send another event (but not add or remove), for the already created
> object. CPU hotplug uses ONLINE/OFFLINE, and we also use it to get
> notified when the device mapper table is set up (not upstream). Udev is
> able to update symlinks, or run actions on "online" events if asked
> for. 

the attached patch sends ONLINE when a device has been attached to a
class device and OFFLINE when it has been removed.

Regards

Marcel