| Date | Thu, 15 May 2014 01:57:58 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [patch 03/32] genirq: Provide generic hwirq allocation facility |
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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 <cmetcalf@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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