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    SubjectRe: [PATCH 5/6] firewire: SBP-2 highlevel driver
    Christoph Hellwig wrote:
    >> >> + sd->scsi_host->hostdata[0] = (unsigned long)unit;
    > scsi_host_alloc
    > is designed to allocate space for your private data aswell. So you
    > should call it early on an allocate the sbp2_device as part of the Scsi_Host
    > instead of just stuffing in a pointer.

    Aha, OK.

    As long as we have 1 SBP-2 target LU == 1 instance of struct Scsi_Host,
    the usage of ->hostdata as backpointer to an fw_unit is appropriate
    though. The lifetime of the fw_unit starts before and ends after that
    of the Scsi_Host. Of course if we reorganize this to use Scsi_Host more
    as a representation of an SBP-2 initiator port (or for all our initiator
    ports at once), some oddities like this ->hostdata usage will go away.

    >> > The discovery of LUs of SBP-2 targets happens on the IEEE 1212
    >> > level of things.
    > Okay, so sbp2 decided to be non-standard here, what a pity.

    Well, SBP-2 (the spec) is from the earlier days when the SCSI
    Architecture Model was young and there didn't exist that many other SCSI
    transports/interconnects besides SCSI Parallel Interconnect. And for
    better or worse, SBP-3 inherited this part of SBP-2's specialties.

    > It's probably better to use scsi_scan_target with a specific lun,
    > though as scsi_add_device is a rather awkward API.

    Looking into these things were on my long-term agenda for mainline's
    sbp2 driver anyway. My plans just got dragged out when I expanded my
    activities from ieee1394/sbp2 to ieee1394/. As far as fw-sbp2 is
    concerned, I don't know if these issues (which it merely took over from
    sbp2) need to be addressed before integration into mainline. fw-sbp2 is
    something in the middle between a new submission and a gradual update.

    Do you see the TODOs related to integration with the SCSI stack (which
    apply to sbp2 as well) as blocking for fw-sbp2?

    Thanks for looking into it and for all the advice,
    Stefan Richter
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