Re: [PATCH 03/11] genirq: Export irq_set_affinity_locked()

[Thomas Gleixner]

On Mon, Sep 27 2021 at 10:47, Florian Fainelli wrote:
> On 9/25/21 2:37 PM, Thomas Gleixner wrote:
>>> I wanted to kill these callbacks years ago. Cavium has two variants of
>>> those offline/online callbacks:
>>>
>>>  1) octeon_irq_cpu_offline_ciu() which is doing the same as that BCM
>>>     driver. These really can go away. Just remove the callback and
>>>     everything just works.
>> 
>> For BCM this works today when that chip is used on ARM[64] simply
>> because the only architecture which invokes irq_cpu_offline() is MIPS.
>
> That is correct. How would you recommend addressing that? In premise
> when this driver is used on ARM[64] it is used as a second level
> interrupt controller hanging off the ARM GIC (or another ARM CPU
> interrupt controller), so in that case I suppose I could make the
> irq_set_cpu_offline be dependent upon CONFIG_SMP and CONFIG_MIPS, would
> that be acceptable?

Why? Just get rid of the callback in that driver and ensure that
irq_migrate_all_off_this_cpu() is invoked when the CPU dies.

arch/mips/kernel/smp-cps.c already does that, but I don't know whether
your MIPS platform uses those SMP ops. If not you surely have a template
there.

Thanks,

        tglx