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

Marc Zyngier
2021-10-22T10:05:35Z

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.

M.

--
Without deviation from the norm, progress is not possible.