Re: [PATCH 04/15] irq: simplify handle_domain_{irq,nmi}()

Marc Zyngier
2021-10-22T10:52:37Z

On Thu, 21 Oct 2021 19:02:25 +0100,
Mark Rutland <mark.rutland@arm.com> wrote:
>
> There's no need for handle_domain_{irq,nmi}() to open-code the NULL
> check performed by handle_irq_desc(), nor the resolution of the desc
> performed by generic_handle_domain_irq().
>
> Use generic_handle_domain_irq() directly, as this is functioanlly
> equivalent and clearer. At the same time, delete the stale comments,
> which are no longer helpful.
>
> There should be no functional change as a result of this patch.
>
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> ---
> kernel/irq/irqdesc.c | 24 ++++--------------------
> 1 file changed, 4 insertions(+), 20 deletions(-)
>
> diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
> index 4e3c29bb603c..b07d0e1552bc 100644
> --- a/kernel/irq/irqdesc.c
> +++ b/kernel/irq/irqdesc.c
> @@ -690,17 +690,11 @@ int handle_domain_irq(struct irq_domain *domain,
> unsigned int hwirq, struct pt_regs *regs)
> {
> struct pt_regs *old_regs = set_irq_regs(regs);
> - struct irq_desc *desc;
> - int ret = 0;
> + int ret;
>
> irq_enter();
>
> - /* The irqdomain code provides boundary checks */
> - desc = irq_resolve_mapping(domain, hwirq);
> - if (likely(desc))
> - handle_irq_desc(desc);
> - else
> - ret = -EINVAL;
> + ret = generic_handle_domain_irq(domain, hwirq);
>
> irq_exit();
> set_irq_regs(old_regs);
> @@ -721,24 +715,14 @@ int handle_domain_nmi(struct irq_domain *domain, unsigned int hwirq,
> struct pt_regs *regs)
> {
> struct pt_regs *old_regs = set_irq_regs(regs);
> - struct irq_desc *desc;
> - int ret = 0;
> + int ret;
>
> /*
> * NMI context needs to be setup earlier in order to deal with tracing.
> */
> WARN_ON(!in_nmi());
>
> - desc = irq_resolve_mapping(domain, hwirq);
> -
> - /*
> - * ack_bad_irq is not NMI-safe, just report
> - * an invalid interrupt.
> - */
> - if (likely(desc))
> - handle_irq_desc(desc);
> - else
> - ret = -EINVAL;
> + ret = generic_handle_domain_irq(domain, hwirq);
>
> set_irq_regs(old_regs);
> return ret;

Yup, that's really neat. I somehow missed that when I moved some of
the legacy stuff to be ARM specific.

On a vaguely related note, I think you can drop the EXPORT_SYMBOL_GPL
on handle_irq_desc() now.

M.

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