Re: [PATCH 1/3] x86, irq: Rename VECTOR_UNDEFINED and VECTOR_RETRIGGERED to IRQ_*

[Bjorn Helgaas <bhelgaas@google.com>]

On Fri, Jul 17, 2015 at 9:06 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
> On Sun, 12 Jul 2015, Bjorn Helgaas wrote:
>
>> The per-cpu vector_irq[] table is indexed by CPU vector numbers, and each
>> entry contains an IRQ number.
>>
>> Rename the special values VECTOR_UNDEFINED and VECTOR_RETRIGGERED to
>> IRQ_UNDEFINED and IRQ_RETRIGGERED to indicate that they are in the IRQ
>> number space, not the CPU vector number space.
>
> Makes some sense, but OTOH vector_irq actually reflects the vector
> state not the irq number state. The fact that we store the Linux irq
> number in vector_irq is just an implementation detail.
>
> VECTOR_UNDEFINED is certainly a misnomer; that should be VECTOR_UNUSED
>
> VECTOR_RETRIGGERED is pretty accurate. In the case we retrigger an
> interrupt, we merily use the Linux irq number to figure out which
> vector to kick. And after we retriggered it, we lose the association
> to the Linux irq number completely.
>
> That said, I'm working on storing the irq descriptor pointer in
> vector_irq instead of the irq number, which has the advantage that we
> avoid the lookup of the irq descriptor in the interrupt hotpath.

OK, I'll abandon this.  Thanks for taking a look!

Bjorn