Hi,

This patch makes xenbus and net/blkfront drivers correctly handle
device_shutdown().  Changes:

  * new xenbus_strstate() helper function for fancy debug output.
  * add xenbus_dev_shutdown() function which switches the devices
    into Closing state and waits for them to finish shutdown.
  * new helper function xenbus_closing_done(), which handles the
    final state transition and informs xenbus_dev_shutdown().

xenbus_closing_done() behaves differently depending on how the closing
was triggered.  If it was triggered by the backend the frontend acks the
removal by going to CLosed.  If it was triggered via device_shutdown()
the state is set back to "Initializing", to allow a possible new kernel
instance to reuse the devices (for domU kexec again ;)

cheers,

  Gerd

-- 
Gerd Hoffmann <kraxel@suse.de>
http://www.suse.de/~kraxel/julika-dora.jpeg