On Tue, Jul 06, 2021 at 12:16:37PM +0200, Arnd Bergmann wrote:
> On Tue, Jul 6, 2021 at 6:18 AM Huacai Chen <chenhuacai@xxxxxxxxxxx> wrote:
>
> > +void arch_cpu_idle(void)
> > +{
> > + local_irq_enable();
> > + __arch_cpu_idle();
> > +}
>
> This looks racy: What happens if an interrupt is pending and hits before
> entering __arch_cpu_idle()?
They fix it up in their interrupt handler by moving the IP over the
actual IDLE instruction..
Still the above is broken in that local_irq_enable() will have all sorts
of tracing, but RCU is disabled at this point, so it is still very much
broken.
