The attached patch is making the SCSI "mid-layer" vomit bag usable again.
I have fixed some very ugly offenders as well in due course:

1. Moved the "informative" scsi_device_types[MAX_SCSI_DEVICE_CODE];
2. Unneccessary/inappriopriate locking in ppa.c
3. "Write only" field in Scsi_CD struct:
     unsigned readcd_cdda:1;    /* reading audio data using READ_CD */

    It get's only set but is never used and never needed.

After having a look at this SCSI code I really got the opinnion that it 
was written
buy someone who didn't know what functions and local variables are good for.
Everything there seems to be done in a maximally terse style...

Anyway.