io_uring: synchronise ev_posted() with waitqueues

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waitqueue_active() needs smp_mb() to be in sync with waitqueues
modification, but we miss it in io_cqring_ev_posted*() apart from
cq_wait() case.

Take an smb_mb() out of wq_has_sleeper() making it waitqueue_active(),
and place it a few lines before, so it can synchronise other
waitqueue_active() as well.

The patch doesn't add any additional overhead, so even if there are
no problems currently, it's just safer to have it this way.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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Pavel Begunkov 2021-01-07 03:15:43 +00:00 • committed by Jens Axboe

parent 4aa84f2ffa

commit b1445e59cc

1 changed files with 8 additions and 2 deletions

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fs/io_uring.c

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