Re: [PATCH] clear irq pending when bypassing it

[Eric W. Biederman]

Joe Korty <joe.korty@xxxxxxxx> writes:

> On Thu, Apr 30, 2009 at 12:49:39PM -0400, Eric W. Biederman wrote:
>> Joe Korty <jak@xxxxxxxxxxxxxxxx> writes:
>> 
>> > IRQ_MOVE_PENDING must be cleared whenever it is bypassed.
>> >
>> > Otherwise, we risk an old, pending affinity change
>> > overtaking and erasing a more recent affinity change that
>> > had been directly applied (eg, IRQ_MOVE_PCNTXT mode).
>> 
>> When can this happen?
>
> Probably doesn't happen.  AFAIK, each IRQ is either fully MSI
> or non-MSI.  The MSI IRQs will always use IRQ_MOVE_PCNTXT and
> the non-MSI's will never use IRQ_MOVE_PCNTXT.  Thus no collision.
>
> It could only happen if it was possible for a MSI and non-MSI
> device to share an IRQ.

Ok.  I thought you might have seen something.

It doesn't happen and it can't happen, making your patch wrong.

Eric





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