More irqdomain problems (Was: next/mmotm unbootable on G5: irqdomain)

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

Allright, another one Grant:

unsigned int irq_find_mapping(struct irq_domain *domain,
			      irq_hw_number_t hwirq)
{
	struct irq_data *data;

	/* Look for default domain if nececssary */
	if (domain == NULL)
		domain = irq_default_domain;
	if (domain == NULL)
		return 0;

	switch (domain->revmap_type) {
	case IRQ_DOMAIN_MAP_LEGACY:
		return irq_domain_legacy_revmap(domain, hwirq);
	case IRQ_DOMAIN_MAP_LINEAR:
		return irq_linear_revmap(domain, hwirq);
	case IRQ_DOMAIN_MAP_TREE:
		rcu_read_lock();
		data = radix_tree_lookup(&domain->revmap_data.tree, hwirq);
		rcu_read_unlock();
		if (data)
			return data->irq;
-               break;
+               return 0;
	case IRQ_DOMAIN_MAP_NOMAP:

Please, stick a proper commit message and my s-o-b and see if you can fix
your tree before you ask Linus to pull because that's not pretty on any
pseries .... irq_find_mapping() does get called for all interrupt the
first time it's mapped to check if there's a pre-existing mapping, so
the case of the thing being unpopulated is absolutely legit.

the NOMAP case has a similar dubious exit case but since I'm not that
familiar with NOMAP I haven't touched it.

Cheers,
Ben.