irqchip/msi-lib: Fix fwnode refcount in msi_lib_irq_domain_select()

Commit 8b65db1e93a2 ("irqchip/msi-lib: Add IRQ_DOMAIN_FLAG_FWNODE_PARENT
handling") added logic in msi_lib_irq_domain_select() to match the domain
fwnode against the fwnode parent of the fwspec.fwnode.

The fwnode_get_parent() caller must call fwnode_handle_put() on the
returned pointer value, lest fwnode refcounting for the parent ends up
being out of kilter.

Fix this by relying on the fwnode_handle clean-up handlers and by
incrementing the fwnode refcount regardless of whether parent matching is
used or not (the domain selection code already holds a reference before
calling msi_lib_irq_domain_select() but to make the exit path more uniform
if IRQ_DOMAIN_FLAG_FWNODE_PARENT is not set fwnode_handle_get() is called
again on fwspec.fwnode so that the clean-up code is the same for the two
matching patterns).

Fixes: 8b65db1e93a2 ("irqchip/msi-lib: Add IRQ_DOMAIN_FLAG_FWNODE_PARENT handling")
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250804145553.795065-1-lpieralisi@kernel.org

diff --git a/drivers/irqchip/irq-msi-lib.c b/drivers/irqchip/irq-msi-lib.c
index 454c7f16dd4d6fb4093ee3e5526555d944657b95..908944009c210bcae7d32d781736651417cdb145 100644 (file)
--- a/drivers/irqchip/irq-msi-lib.c
+++ b/drivers/irqchip/irq-msi-lib.c
@@ -133,13 +133,13 @@ int msi_lib_irq_domain_select(struct irq_domain *d, struct irq_fwspec *fwspec,
 {
        const struct msi_parent_ops *ops = d->msi_parent_ops;
        u32 busmask = BIT(bus_token);
-       struct fwnode_handle *fwh;
 
        if (!ops)
                return 0;
 
-       fwh = d->flags & IRQ_DOMAIN_FLAG_FWNODE_PARENT ? fwnode_get_parent(fwspec->fwnode)
-                                                      : fwspec->fwnode;
+       struct fwnode_handle *fwh __free(fwnode_handle) =
+               d->flags & IRQ_DOMAIN_FLAG_FWNODE_PARENT ? fwnode_get_parent(fwspec->fwnode)
+                                                        : fwnode_handle_get(fwspec->fwnode);
        if (fwh != d->fwnode || fwspec->param_count != 0)
                return 0;