Re: [PATCH 15/15] irq: remove handle_domain_{irq,nmi}()

Mark Rutland
2021-10-22T15:06:29Z

On Fri, Oct 22, 2021 at 11:05:29AM +0100, Marc Zyngier wrote:
> On Thu, 21 Oct 2021 19:02:36 +0100,
> Mark Rutland <mark.rutland@arm.com> wrote:
> >
> > Now that entry code handles IRQ entry (including setting the IRQ regs)
> > before calling irqchip code, irqchip code can safely call
> > generic_handle_domain_irq(), and there's no functional reason for it to
> > call handle_domain_irq().
> >
> > Let's cement this split of responsibility and remove handle_domain_irq()
> > entirely, updating irqchip drivers to call generic_handle_domain_irq().
> >
> > For consistency, handle_domain_nmi() is similarly removed and replaced
> > with a generic_handle_domain_nmi() function which also does not perform
> > any entry logic.
> >
> > Previously handle_domain_{irq,nmi}() had a WARN_ON() which would fire
> > when they were called in an inappropriate context. So that we can
> > identify similar issues going forward, similar WARN_ON_ONCE() logic is
> > added to the generic_handle_*() functions, and comments are updated for
> > clarity and consistency.
> >
> > Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> > Cc: Marc Zyngier <maz@kernel.org>
> > Cc: Thomas Gleixner <tglx@linutronix.de>
>
> [...]
>
> > -/**
> > - * handle_domain_nmi - Invoke the handler for a HW irq belonging to a domain
> > - * @domain: The domain where to perform the lookup
> > - * @hwirq: The HW irq number to convert to a logical one
> > - * @regs: Register file coming from the low-level handling code
> > - *
> > - * This function must be called from an NMI context.
> > *
> > - * Returns: 0 on success, or -EINVAL if conversion has failed
> > - */
> > -int handle_domain_nmi(struct irq_domain *domain, unsigned int hwirq,
> > - struct pt_regs *regs)
> > + * This function must be called from an NMI context with irq regs
> > + * initialized.
> > + **/
> > +int generic_handle_domain_nmi(struct irq_domain *domain, unsigned int hwirq)
> > {
> > - struct pt_regs *old_regs = set_irq_regs(regs);
> > - int ret;
> > -
> > - /*
> > - * NMI context needs to be setup earlier in order to deal with tracing.
> > - */
> > - WARN_ON(!in_nmi());
> > -
> > - ret = generic_handle_domain_irq(domain, hwirq);
> > -
> > - set_irq_regs(old_regs);
> > - return ret;
> > + WARN_ON_ONCE(!in_nmi());
> > + return handle_irq_desc(irq_resolve_mapping(domain, hwirq));
> > }
> > -#endif
> > +EXPORT_SYMBOL_GPL(generic_handle_domain_nmi);
>
> nit: we don't need this export (only a root controller can handle
> NMIs), and that's the sort of thing I would really want to avoid
> exposing to modules.

Sure, I'll drop that; I'd only added that for symmetry with
generic_handle_domain_irq(), and I don't need it to be exported.

Thanks,
Mark.