On Wed, 14 May 2014, Chris Metcalf wrote:
> On 5/7/2014 7:15 PM, Thomas Gleixner wrote:
> > On Wed, 7 May 2014, Chris Metcalf wrote:
> > > We have an internal change that we haven't upstreamed yet that makes
> > > irqs actually (cpu,ipi) pairs, so that more irqs can be allocated.
> > > As a result we allocate some irqs as bound to a specific IPI on a single
> > > cpu, and some irqs get bound to a particular IPI registered on every cpu.
> > >
> > > I'll have to set aside a bit of time to look more closely at how your
> > > change interacts with the work we've done internally. I've appended the
> > > per-cpu IRQ change from our internal tree here (and cc'ed the author).
> > > The API change is in the <asm/irq.h> diff at the very start.
> > Sure it'll break it. [...]
>
> I think the right thing for now is to take my Acked-by for the tile changes
> (given a couple of minor nits replied to in separate emails).
>
> Acked-by: Chris Metcalf <cmetc...@tilera.com>
Thanks.
> When we have the chance to set aside some time for more upstreaming of some
> of the work we've done it does seem like it makes sense to tackle doing some
> kind of matrix mapping in a more generic way.
Please coordinate with x86 folks on that to avoid redundant efforts.
> You're probably right that a cpumask approach would have made more sense
> than a cpu integer in the tile API, so we'd certainly go with that in any
> generic matrix mapping code.
Anything else is just an intermediate and non generic solution.
> I do have one question about the irq_alloc_hwirqs() API, which is
> the use of zero as an error indicator. Given that zero can
> plausibly be an IRQ number, it seems cleaner to specify this as
> returning a negative errno failure instead. Doing so would also
> align with __irq_alloc_descs(). So, what was your thinking around
> using zero?
0 has been for a long time a not allocatable irq. Google will unearth
about a gazillion heated debates about that.
I personally agree, that using a negative error code is the right
thing to do. I'll update the series before I push it into tip.
Thanks for your input and cooperation!
tglx
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