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    SubjectRe: sbp2.c on SMP
    On Sun, Nov 11, 2001 at 05:37:21PM -0800, Andrew Morton wrote:
    >
    > With the appended patch I can confirm that the driver happily runs
    > `dbench 40' for half an hour on dual x86. Even when you kick the

    Thanks a lot.

    > disk onto the floor (sorry, HJ).

    That is a good stress test.

    >
    > The games which scsi_old_done() plays with spinlocks and interrupt
    > enabling are really foul. If someone calls it with interrupts disabled
    > (sbp2 does this) then scsi_old_done() will enable interrupts for you.
    > If, for example, you call scsi_old_done() under spin_lock_irqsave(),
    > the reenabling of interrupts will expose you to deadlocks. Perhaps
    > scsi_old_done() should just use spin_unlock()/spin_lock()?
    >
    > I tried enabling SBP2_USE_REAL_SPINLOCKS in sbp2.c and that appears to
    > work just fine, although I haven't left that change in place here.
    >
    > You don't actually _need_ SMP hardware to test SMP code, BTW. You
    > can just build an SMP kernel and run that on a uniprocessor box.
    > This will still catch a wide range of bugs - it certainly detects
    > the lockup which was occurring because of the scsi_old_done() thing.
    >
    > Incidentally, it would be nice to be able to get this driver working
    > properly when linked into the kernel - it makes debugging much easier :)
    >

    I guess I can try that. The only main issue will be the order of
    initialization.



    H.J.
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