[PATCH] powerpc/irq: Improve/fix migrate_irqs()

[Michael Ellerman]

Benjamin Herrenschmidt <benh at kernel.crashing.org> writes:

> migrate_irqs() is used by some platforms to migrate interrupts
> away from a CPU about to be offlined.
>
> The current implementation had various issues such as not taking
> the descriptor lock before manipulating it.

... and not checking for a NULL chip (but presumably that's never
happened), and always calling irq_set_affinity() even for IRQs not on
the CPU.

But, any reason we can't use irq_migrate_all_off_this_cpu() ?
Which is in generic code.

cheers