[PATCH kernel v4 7/8] genirq/irqdomain: Reference irq_desc for already mapped irqs

[Alexey Kardashevskiy <aik@ozlabs.ru>]

This references an irq_desc if already mapped interrupt requested to map
again. This happends for PCI legacy interrupts where 4 interrupts are
shared among all devices on the same PCI host bus adapter.

From now on, the users shall call irq_dispose_mapping() for every
irq_create_fwspec_mapping(). Most (all?) users do not bother with
disposing though so it is not very likely to break many things.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 kernel/irq/irqdomain.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index a0a81cc6c524..07f4bde87de5 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -663,7 +663,9 @@ unsigned int irq_create_mapping(struct irq_domain *domain,
 	/* Check if mapping already exists */
 	virq = irq_find_mapping(domain, hwirq);
 	if (virq) {
+		desc = irq_to_desc(virq);
 		pr_debug("-> existing mapping on virq %d\n", virq);
+		kobject_get(&desc->kobj);
 		return virq;
 	}
 
@@ -762,6 +764,7 @@ unsigned int irq_create_fwspec_mapping(struct irq_fwspec *fwspec)
 	irq_hw_number_t hwirq;
 	unsigned int type = IRQ_TYPE_NONE;
 	int virq;
+	struct irq_desc *desc;
 
 	if (fwspec->fwnode) {
 		domain = irq_find_matching_fwspec(fwspec, DOMAIN_BUS_WIRED);
@@ -798,8 +801,11 @@ unsigned int irq_create_fwspec_mapping(struct irq_fwspec *fwspec)
 		 * current trigger type then we are done so return the
 		 * interrupt number.
 		 */
-		if (type == IRQ_TYPE_NONE || type == irq_get_trigger_type(virq))
+		if (type == IRQ_TYPE_NONE || type == irq_get_trigger_type(virq)) {
+			desc = irq_to_desc(virq);
+			kobject_get(&desc->kobj);
 			return virq;
+		}
 
 		/*
 		 * If the trigger type has not been set yet, then set
@@ -811,6 +817,8 @@ unsigned int irq_create_fwspec_mapping(struct irq_fwspec *fwspec)
 				return 0;
 
 			irqd_set_trigger_type(irq_data, type);
+			desc = irq_to_desc(virq);
+			kobject_get(&desc->kobj);
 			return virq;
 		}
 
-- 
2.17.1