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    SubjectRe: [PATCH] firewire-sbp2: Initialise sbp2_orb->rcode for management ORBs
    On Mar 04 Stefan Richter wrote:
    > On Feb 18 Chris Boot wrote:
    > > When sending ORBs the struct sbp2_orb->rcode field should be initialised
    > > to -1 otherwise complete_transaction() assumes the request is successful
    > > (RCODE_COMPLETE is 0). When sending managament ORBs, such as LOGIN or
    > > LOGOUT, this was not done and so the initiator would wait for the
    > > request to time out before trying again.
    > >
    > > Without this, LOGINs are only retried when the management ORB times out,
    > > rather than the initiator noticing an error occurred and retrying soon
    > > after. For targets that advertise more than one LUN per unit, and can
    > > only accept one management request at a time, this means LUNs are only
    > > logged in one per timeout period.
    [...]
    > I left this hanging in my inbox for too long, sorry...
    >
    > While I agree that the current initialization of orb->base.rcode with 0 is
    > wrong, I don't think your change alone is sufficient:
    >
    > Consider the case that a login request to LU 0 causes the target to pull
    > out the hardware behind that LU out of a powered-down state --- which may
    > take a very long time --- and login requests to LU 1 would be aborted by
    > the target with resp_conflict_error on any Management_Agent write
    > request. Of course a reasonably clever target would accept login before
    > full power-up, but you never now.
    >
    > We retry login 5 times in 0.2 seconds intervals, and this 1 s in total may
    > not be enough.
    [...]

    Chris, I obviously haven't done anything about this potentially too short
    retry period yet; it is still on my list.

    Perhaps we should not count the number of retries but watch the time that
    retries take. I.e. accumulate the time that each try takes; break out of
    the retry loop after a maximum time; but reset the accumulated time at a
    bus reset as a precaution for buses with many nodes coming online at
    different times.
    --
    Stefan Richter
    -=====-===-- -=-= =--==
    http://arcgraph.de/sr/


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