irqdomain: Fix mapping-creation race

Parallel probing of devices that share interrupts (e.g. when a driver
uses asynchronous probing) can currently result in two mappings for the
same hardware interrupt to be created due to missing serialisation.

Make sure to hold the irq_domain_mutex when creating mappings so that
looking for an existing mapping before creating a new one is done
atomically.

Fixes: 765230b5 ("driver-core: add asynchronous probing support for drivers")
Fixes: b62b2cf5 ("irqdomain: Fix handling of type settings for existing mappings")
Link: https://lore.kernel.org/r/YuJXMHoT4ijUxnRb@hovoldconsulting.com


Cc: stable@vger.kernel.org      # 4.8
Cc: Dmitry Torokhov <dtor@chromium.org>
Cc: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Hsin-Yi Wang <hsinyi@chromium.org>
Tested-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230213104302.17307-7-johan+linaro@kernel.org