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    SubjectRe: [PATCH] uio: User IRQ Mode
    On Fri, Jul 4, 2008 at 4:55 AM, Hans J. Koch <> wrote:
    > On Thu, Jul 03, 2008 at 10:23:16PM +0900, Paul Mundt wrote:
    >> On Thu, Jul 03, 2008 at 02:45:05PM +0200, Hans J. Koch wrote:
    >> > On Thu, Jul 03, 2008 at 09:10:19AM +0200, Uwe Kleine-K??nig wrote:
    >> > > Moreover this might prevent some bugs. (And obviously this
    >> > > function has the potential to have a buggy implementation as
    >> > > the comment by Alan Cox shows.)
    >> >
    >> > For me, this shows two things:
    >> >
    >> > - I never ever had to use disable_irq_nosync() in any UIO driver yet,
    >> > otherwise I would have noticed.
    >> >
    >> > - Magnus turned in a patch that he never tested.
    >> >
    >> Note that the deadlock in question is in relation to SMP, it's true that
    >> the patch was never tested in an SMP environment and only on UP, but it
    >> certainly was tested.
    > Ok, so I take back that accusation ;-)

    That's good, thank you. In the future it would be even better if you
    didn't accuse to begin with, since that will only heat up the

    > Nonetheless, the patch changes a UIO core file, and everything in there
    > should work in all situations on all architectures unless there is a
    > _very_ good reason to do something different. This not only applies to
    > SMP issues but also to the limitation to non-shared interrupts.

    I will resolve the SMP issue and repost, no problem.

    >> The vast majority of driver writers don't have a
    >> need to use disable_irq_nosync(), so whether you've had to use it or not
    >> is largely irrelevant to the conversation at hand ;-)
    > Sure ;-) I merely wanted to point out that this is an unusual way to
    > handle an interrupt.

    Grep shows that there is nothing unusual about it.

    damm@rx1 ~/git/linux-2.6 $ find drivers/ | xargs grep -m 1 -e
    [[:blank:]]disable_irq\( -e [[:blank:]]disable_irq_nosync\( | wc -l

    / magnus

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