irqdomain: Look for existing mapping only once

stable inclusion
from stable-v5.10.175
commit ff762cdbf0c8c9bf0b97684f39af13b3332e77e8
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8711T

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ff762cdbf0c8c9bf0b97684f39af13b3332e77e8



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[ Upstream commit 6e6f75c9 ]

Avoid looking for an existing mapping twice when creating a new mapping
using irq_create_fwspec_mapping() by factoring out the actual allocation
which is shared with irq_create_mapping_affinity().

The new helper function will also be used to fix a shared-interrupt
mapping race, hence the Fixes tag.

Fixes: b62b2cf5 ("irqdomain: Fix handling of type settings for existing mappings")
Cc: stable@vger.kernel.org      # 4.8
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/20230213104302.17307-5-johan+linaro@kernel.org


Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>