RE: [PATCH 2.6.21-rc5] MSI: read-flush MSI-X table

[Williams, Mitch A]

Eric W. Biederman wrote:

>> However the mask function is called at EVERY interrupt,
>> so this change would be VERY expensive.
>
>If true I think that would be bad.  However I don't see it.
>Where in handle_edge_irq do we mask the interrupt?
>The only place I see us calling ->mask is from move_native_irq
>and that only if IRQ_MOVE_PENDING is true.
>
>All I can see is us routinely calling is ack_APIC_edge.

Doh!  I was reading the code wrong.  We only mask if we're still
handling a previous interrupt on the same vector.  My bad.

However, I can't really see where mask() is used outside of that
instance.  Which then leads us back to the question:  do we need
a read flush on mask/unmask or just enable/disable?

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