Messages in this thread | | | Date | Thu, 3 Jul 2008 21:55:38 +0200 | From | "Hans J. Koch" <> | Subject | Re: [PATCH] uio: User IRQ Mode |
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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 ;-) 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.
> 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.
Thanks, Hans
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