Re: [PATCH v13 3/7] arm64: smp: Remove dedicated wakeup IPI

[Doug Anderson]

Hi,

On Mon, Sep 25, 2023 at 5:39 PM Doug Anderson <dianders@xxxxxxxxxxxx> wrote:
>
> Mark,
>
> On Wed, Sep 6, 2023 at 9:06 AM Douglas Anderson <dianders@xxxxxxxxxxxx> wrote:
> >
> > +#ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
> > +void arch_send_wakeup_ipi(unsigned int cpu)
> > +{
> > +       /*
> > +        * We use a scheduler IPI to wake the CPU as this avoids the need for a
> > +        * dedicated IPI and we can safely handle spurious scheduler IPIs.
> > +        */
> > +       arch_smp_send_reschedule(cpu);
>
> I was backporting this to our ChromeOS kernels and our build test bot
> noticed that arch_smp_send_reschedule() didn't exist in older kernels.
> That's fine--I can always adjust this patch when backporting or
> cherry-pick extra patches, but it made me wonder. Is there a reason
> you chose to use arch_smp_send_reschedule() directly here instead of
> smp_send_reschedule()? I guess the only difference is that you're
> bypassing the tracing. Is that on purpose? Should we add a comment
> about it, or change this to smp_send_reschedule()?

FWIW, I posted a patch changing this to smp_send_reschedule(). Please
yell if this is incorrect.

https://lore.kernel.org/r/20231002094526.2.I2e6d22fc42ccbf6b26465a28a10e36e05ccf3075@changeid