Re: [PATCH 2/2] x86_64 irq: Handle irqs pending in IRR during irq migration.

[Eric W. Biederman]

Ingo Molnar <mingo@xxxxxxx> writes:

> * Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:
>
>> Ingo would it be reasonable to get a wait queue so I can wait for an 
>> irq that needs the delayed disable action to actually become masked?
>
> that might make sense, but what will do the wakeup - incidental IRQ 
> arriving on the new CPU? 

That is what I was thinking.

> Isnt that a bit risky - maybe the device wont 
> generate IRQs for a really long time.

Well this is in a user space context called from user space and it
exactly matches the semantics we have now.  If we make it an
interruptible sleep the user space process shouldn't block.

I guess the other thing to do is do it in a non-block fashion
and just call schedule_work from the interrupt context when the
irq is disabled.  For i386 with it's in kernel irq scheduler
that might be better.

I think the nasty case is probably what do we do when it is
the timer interrupt we are dealing with.

Hmm.  I think I should look up what the rules are for
calling local_irq_enable when in interrupt context.  That
might be another way to satisfy this problem.

If local irqs are enabled I don't have to worry about the irr
register.

You've got me brainstorming now.

Eric
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