So right now scsi_get_host_dev/scsi_free_host_dev is entirely unused.

І'd rather just kill them off rather than giving them a new life and
hacking all over the core code for them.

What do you need the scsi_device for instead of just having a
request_queue for comands to the controller?  If we need a scsi_device
can we somehow make sure it doesn't hit the scanning and sysfs code
from a much higher level?