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

JIRA: https://issues.redhat.com/browse/RHEL-120705
Upstream Status: 02cbf8e

commit 02cbf8e
Author: Lorenzo Pieralisi <lpieralisi@kernel.org>
Date:   Mon Aug 4 16:55:53 2025 +0200

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

    Commit 8b65db1 ("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: 8b65db1 ("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

Signed-off-by: Myron Stowe <mstowe@redhat.com>

Author: Myron Stowe

drivers/irqchip/irq-msi-lib.c

@@ -147,13 +147,13 @@ 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;