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

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