Mike Sullivan
Grant R. Guenther wrote:
>
> The parallel port IDE drivers are broken on SMP machines. The combination
> of PARIDE and SMP might seem a bit odd, but it really happens. People
> like to move data around on SparQ drives, for instance.
>
> Unfortunately, I don't have access to an SMP machine, myself. The only
> reports I get are that the system deadlocks when one of the PARIDE drivers
> is loaded into a 2.1.95 kernel.
>
> There are some unique "features" of the PARIDE drivers. First, they
> do not use interrupts. Instead, both timer queues and task queues are
> used to simulate a stream of "pseudo-interrupts". Secondly, because
> the strategy routines can take a lot of time, the drivers enable
> interrupts (in the rest of the system) for much of their work.
>
> Presumably some of the cli/sti stuff needs to be replaced with spinlocks,
> but without either a test machine or a clear understanding of the issues,
> I'm not in a good position to fix this. For instance, if I re-enable
> interrupts in the strategy routines, is sti() still the right way to do
> that, or should I be releasing some specific spinlock ? Because
> the pseudo interrupts can come from two different queues, there's
> some trickiness to ensure that only one "thread" actually makes it
> back into the driver. I think the mutex code in the two handlers
> should be using a spinlock, but should it be the io_request_lock, or
> a different lock ?
>
> If someone with a good knowledge of SMP issues could please have a look
> at pd.c and pseudo.h in drivers/block/paride/ and give me a hand, I'd
> appreciate it.
>
> Thanks
>
> --------------------------------------------------------------------------
> Grant R. Guenther grant@torque.net
> --------------------------------------------------------------------------
>
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