[BUG] irq_dispose_mapping after irq request failure

[Benjamin Herrenschmidt]

On Tue, 2013-02-12 at 17:18 +1100, Michael Ellerman wrote:
> 
> I don't think you can, "active" is not well defined. Other code may have
> done nothing other than create the mapping and remembered the virq,
> which will break if you destroy the mapping. Or?

Active as in "requested". Yes there's a potential problems with multiple
requests for mappings & shared interrupts. This is not a problem for PCI
on powerpc because we don't free those mappings afaik.

> I agree refcounting is not fun. It'll end up with the same mess as
> of_node_get/put() where practically every 2nd piece of code leaks
> references.
> 
> I guess we can't go the other way, and say that mapping the same hwirq
> twice is an error.

Might be worth it, and force the sharing case to be handled at some kind
of upper level (bus or platform).

Ben.