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

[Marc Zyngier]

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>
Fixes: de1ff306dcf4 ("genirq/irqdomain: Remove the param count restriction from select()")
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240219-gic-fix-child-domain-v1-1-09f8fd2d9a8f@xxxxxxxxxx
---
 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