linux-kernel - Re: [PATCH 1/3] x86, irq: Rename VECTOR_UNDEFINED and VECTOR_RETRIGGERED to IRQ

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Date:	Fri, 17 Jul 2015 12:50:05 -0500
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Linux-Arch <linux-arch@...r.kernel.org>,
	"linux-mips@...ux-mips.org" <linux-mips@...ux-mips.org>,
	linux-am33-list@...hat.com,
	"linux-ia64@...r.kernel.org" <linux-ia64@...r.kernel.org>,
	linux-c6x-dev@...ux-c6x.org, linux-parisc@...r.kernel.org,
	"linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
	"linux-sh@...r.kernel.org" <linux-sh@...r.kernel.org>,
	adi-buildroot-devel@...ts.sourceforge.net,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-m68k@...ts.linux-m68k.org, linux-alpha@...r.kernel.org,
	"x86@...nel.org" <x86@...nel.org>,
	linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH 1/3] x86, irq: Rename VECTOR_UNDEFINED and
 VECTOR_RETRIGGERED to IRQ_*

On Fri, Jul 17, 2015 at 9:06 AM, Thomas Gleixner <tglx@...utronix.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
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