Resubmit the packet unchanged.
Use scsi_sync_pkt(9F) to synchronize the data. Then, process the data in the driver. Finally, resubmit the packet.
Free DMA resources, using scsi_dmafree(9F), and pass the pkt pointer to scsi_init_pkt(9F) for binding to a new bp. The target driver is responsible for reinitializing the packet. The CDB has to have the same length as the previous CDB.
If only partial DMA is allocated during the first call to scsi_init_pkt(9F), subsequent calls to scsi_init_pkt(9F) can be made for the same packet. Calls can be made to bp as well to adjust the DMA resources to the next portion of the transfer.