IB/uverbs: Fix to consider event queue closing also upon non-blocking mode

stable inclusion
from stable-v5.10.185
commit 2f9d26345c6eb3521724d04328d6c25560b2e409
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8L5XP

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2f9d26345c6eb3521724d04328d6c25560b2e409



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[ Upstream commit 62fab312 ]

Fix ib_uverbs_event_read() to consider event queue closing also upon
non-blocking mode.

Once the queue is closed (e.g. hot-plug flow) all the existing events
are cleaned-up as part of ib_uverbs_free_event_queue().

An application that uses the non-blocking FD mode should get -EIO in
that case to let it knows that the device was removed already.

Otherwise, it can loose the indication that the device was removed and
won't recover.

As part of that, refactor the code to have a single flow with regards to
'is_closed' for both blocking and non-blocking modes.

Fixes: 14e23bd6 ("RDMA/core: Fix locking in ib_uverbs_event_read")
Reviewed-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Link: https://lore.kernel.org/r/97b00116a1e1e13f8dc4ec38a5ea81cf8c030210.1685960567.git.leon@kernel.org


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