RE: [PATCH] genirq/irqdomain: Don't call ops->select for DOMAIN_BUS_ANY tokens

[Biju Das]

Hi Marc Zyngier,

> -----Original Message-----
> From: Marc Zyngier <maz@xxxxxxxxxx>
> Sent: Tuesday, February 20, 2024 11:48 AM
> Subject: [PATCH] genirq/irqdomain: Don't call ops->select for
> DOMAIN_BUS_ANY tokens
> 
> Users of the IRQCHIP_PLATFORM_DRIVER_{BEGIN,END} helpers rely on a fwspec
> containing only the fwnode (and crucially a number of parameters set to 0)
> together with a DOMAIN_BUS_ANY token to check whether a parent irqchip has
> probed and registered a domain.
> 
> Since de1ff306dcf4 ("genirq/irqdomain: Remove the param count restriction
> from select()"), we call ops->select unconditionally, meaning that
> irqchips implementing select now need to handle ANY as a match.
> 
> Instead of adding more esoteric checks to the individual drivers, add that
> condition to irq_find_matching_fwspec(), and let it handle the corner
> case, as per the comment in the function.
> 
> This restores the functionnality of the above helpers.
> 
> Reported-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> Tested-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> Reported-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>

Tested-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>

Cheers,
Biju

> Fixes: de1ff306dcf4 ("genirq/irqdomain: Remove the param count restriction
> from select()")
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> Link:
> ---
>  kernel/irq/irqdomain.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c index
> aeb41655d6de..3dd1c871e091 100644
> --- a/kernel/irq/irqdomain.c
> +++ b/kernel/irq/irqdomain.c
> @@ -449,7 +449,7 @@ struct irq_domain *irq_find_matching_fwspec(struct
> irq_fwspec *fwspec,
>  	 */
>  	mutex_lock(&irq_domain_mutex);
>  	list_for_each_entry(h, &irq_domain_list, link) {
> -		if (h->ops->select)
> +		if (h->ops->select && bus_token != DOMAIN_BUS_ANY)
>  			rc = h->ops->select(h, fwspec, bus_token);
>  		else if (h->ops->match)
>  			rc = h->ops->match(h, to_of_node(fwnode), bus_token);
> --
> 2.39.2