genirq: Add mutex to irq desc to serialize request/free_irq()

genirq: Add mutex to irq desc to serialize request/free_irq()

The irq_request/release_resources() callbacks ar currently invoked under
desc->lock with interrupts disabled. This is a source of problems on RT and
conceptually not required.

Add a seperate mutex to struct irq_desc which allows to serialize
request/free_irq(), which can be used to move the resource functions out of
the desc->lock held region.

Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Marc Zyngier <[email protected]>
Cc: Heiko Stuebner <[email protected]>
Cc: Julia Cartwright <[email protected]>
Cc: Linus Walleij <[email protected]>
Cc: Brian Norris <[email protected]>
Cc: Doug Anderson <[email protected]>
Cc: [email protected]
Cc: John Keeping <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]