Re: thinkpad x60: sound problems in 4.15-rc1 was Re: thinkpad x60: sound problems in 4.14.0-next-20171114

[Thomas Gleixner <tglx@linutronix.de>]

On Sat, 23 Dec 2017, vcaputo@pengaru.com wrote:
> On Fri, Dec 22, 2017 at 09:37:01PM -0800, vcaputo@pengaru.com wrote:
> Added the following instrumentation:
> 
> diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
> index 93edc2236282..7034eda4d494 100644
> --- a/arch/x86/kernel/apic/vector.c
> +++ b/arch/x86/kernel/apic/vector.c
> @@ -228,6 +228,9 @@ static int __assign_irq_vector(int irq, struct apic_chip_data *d,
>         cpumask_and(vector_searchmask, vector_searchmask, mask);
>         BUG_ON(apic->cpu_mask_to_apicid(vector_searchmask, irqdata,
>                                         &d->cfg.dest_apicid));
> +
> +       printk("allocated vector=%i maskfirst=%i\n", d->cfg.vector, cpumask_first(vector_searchmask));
> +
>         return 0;
>  }
>  
> This is what I see:
> 
> Upon playing song in cmus (on AC power since boot):
>  Dec 22 22:26:52 iridesce kernel: allocated vector=35 maskfirst=1
> 
> Yank AC:
>  Dec 22 22:27:14 iridesce kernel: allocated vector=51 maskfirst=1
>  Dec 22 22:27:15 iridesce kernel: do_IRQ: 0.35 No irq handler for vector
> 
> So CPU 0 vector 35 got an interrupt when maskfirst=1 for 35 as seen in
> the added printk.
> 
> It seems like the affinity changes are assuming a strict adherence to
> the CPU mask when the underlying hardware is treating it more as a hint.
> Perhaps handlers still need to be maintained on all CPUs in a given apic
> domain, regardless of what the masks are configured as, to cover these
> situations.

That's odd. I'll have a look after the holidays.

Merry Christmas!

Thanks,

	tglx