why is there an empty scsi device ?

Hi,
In linux-2.4 kernels, I notice an empty Scsi_Device structure being added
at the end of Scsi_Host list while detecting the scsi devices [scan_scsis( ) in scsi_scan.c]. This empty structure would get filled later in scan_scsis_single( ), in which case, again an empty device is appended. Can anybody let me know to why the structure is to be added in the linked list before filling up the fields rather than filling it first and adding to the host list later ?

Thanks