Do the ax25_list_lock, ax25_dev_lock, linkfail_lockreally, ax25_frag_lock and
  listen_lock have to be bh-safe?
  
  Do the netrom and rose locks have to be bh-safe?
  
  A device might be deleted after lookup in the SIOCADDRT ioctl but before it's
  being used.
  
  Routes to a device being taken down might be deleted by ax25_rt_device_down
  but added by somebody else before the device has been deleted fully.

  The ax25_rt_find_route synopsys is pervert but I somehow had to deal with
  the race caused by the static variable in it's previous implementation.
  
  Implement proper socket locking in netrom and rose.
  
  Check socket locking when ax25_rcv is sending to raw sockets.  In particular
  ax25_send_to_raw() seems fishy.  Heck - ax25_rcv is fishy.
  
  Handle XID and TEST frames properly.