Re: IRQ affinity enforced only after first interrupt.

[Bjorn Helgaas]

[This is not really a PCI question, so +cc Thomas, LKML.]

On Mon, Mar 26, 2012 at 3:06 AM, Yevgeny Petrilin
<yevgenyp@xxxxxxxxxxxxxx> wrote:
> Hello,
>
> I'm working on an issue where affinity changes to IRQ only have effect after the first interrupt which still happens on the original core.
> I understand that the decision regarding it takes place in this code:
>
>        if (irq_can_move_pcntxt(data)) {
>                ret = chip->irq_set_affinity(data, mask, false);
>                switch (ret) {
>                case IRQ_SET_MASK_OK:
>                        cpumask_copy(data->affinity, mask);
>                case IRQ_SET_MASK_OK_NOCOPY:
>                        irq_set_thread_affinity(desc);
>                        ret = 0;
>                }
>        } else {
>                irqd_set_move_pending(data);
>                irq_copy_pending(desc, mask);
>        }
>
> Which means that the "IRQD_MOVE_PCNTXT" flag is not set in irq_data->state_use_accessors.
> I was able to add this flag using irq_modify_status(), which is probably not the way to go.
> This option also doesn't exist in older kernels (2.6.32)
>
> So the question is, when irq_desc is created, how is it determined that "IRQD_MOVE_PCNTXT" flag is set?
>
> Thanks,
> Yevgeny
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