2 questions about SCSI initialization

[Pete Zaitcev <zaitcev@redhat.com>]

Hello:

I've got two questions which I cannot answer just by reading
the code, so I need to refer to the institutional memory of
the hackerdom (Doug G. - I need your memory, too :)

The context is that I got a bug with oops by someone with 68 SCSI
disks, traceable to a scsi_build_commandblocks failure, with a
subsequent oops because the error patch calls scsi_unregister_device,
and scsi_unregister_device aborts with module reference check.

Now the questions:

#1: Why does scsi_build_commandblocks() allocate memory with
GFP_ATOMIC? It's not called from an interrupt or from a swap I/O
path as far as I can see.

#2: What does  if (GET_USE_COUNT(tpnt->module) != 0)  do in
scsi_unregister_device? The circomstances are truly bizzare:
a) the error code is NEVER used
b) it can be called either from module unload.
I would like to kill that check.

Thanks,
-- Pete