irqchip/mips: Fix RCU violation when using irqdomain lookup on interrupt entry

Since d4a45c68dc81 ("irqdomain: Protect the linear revmap with RCU"),
any irqdomain lookup requires the RCU read lock to be held.

This assumes that the architecture code will be structured such as
irq_enter() will be called *before* the interrupt is looked up
in the irq domain. However, this isn't the case for MIPS, and a number
of drivers are structured to do it the other way around when handling
an interrupt in their root irqchip (secondary irqchips are OK by
construction).

This results in a RCU splat on a lockdep-enabled kernel when the kernel
takes an interrupt from idle, as reported by Guenter Roeck.

Note that this could have fired previously if any driver had used
tree-based irqdomain, which always had the RCU requirement.

To solve this, provide a MIPS-specific helper (do_domain_IRQ())
as the pendent of do_IRQ() that will do thing in the right order
(and maybe save some cycles in the process).

Ideally, MIPS would be moved over to using handle_domain_irq(),
but that's much more ambitious.

Reported-by: Guenter Roeck <[email protected]>
Tested-by: Guenter Roeck <[email protected]>
[maz: add dependency on CONFIG_IRQ_DOMAIN after report from the kernelci bot]
Signed-off-by: Marc Zyngier <[email protected]>
Cc: Thomas Bogendoerfer <[email protected]>
Cc: Serge Semin <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Link: https://lore.kernel.org/r/[email protected]

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