Driver changes: Make backend drivers check it when entering Closed
state, only unregister devices when the "online" node is either "0" or
not present. The later maintains backward compatibility.
Tools changes: Update "online" node when creating and hot-unplugging
devices.
Background: When kexec'ing a new kernel, the old kernel's frontend
driver will shutdown, but the backend device should *NOT* disappear
due to that, so the new kernel instance can reconnect.
Signed-off-by: Gerd Hoffmann <kraxel@suse.de>
kaf24@firebug.cl.cam.ac.uk
5182367c40