Subject: Re: [PATCH tip:irq/core v1] genirq: remove auto-set of the mask when setting the hint

From: Thomas Gleixner <[email-masked]>
Date: Mon, 17 May 2021 21:47:12 +0200

Nitesh,

On Mon, May 17 2021 at 14:21, Nitesh Lal wrote:
> On Mon, May 17, 2021 at 1:26 PM Robin Murphy <[email-masked]> wrote:
>
> We can use irq_set_affinity() to set the hint mask as well, however, maybe
> there is a specific reason behind separating those two in the
> first place (maybe not?).

Yes, because kernel side settings might overwrite the hint.

> But even in this case, we have to either modify the PMU drivers' IRQs
> affinity from the userspace or we will have to make changes in the existing
> request_irq code path.

Adjusting them from user space does not work for various reasons,
especially CPU hotplug.

> I am not sure about the latter because we already have the required controls
> to adjust the device IRQ mask (by using default_smp_affinity or by modifying
> them manually).

default_smp_affinity does not help at all and there is nothing a module
can modify manually.

I'll send out a patch series which cleans that up soon.

Thanks,

        tglx