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io_uring: fix tw losing poll events 

We may never try to process a poll wake and its mask if there was
multiple wake ups racing for queueing up a tw. Force
io_poll_check_events() to update the mask by vfs_poll().

Cc: stable@vger.kernel.org
Fixes: aa43477b04 ("io_uring: poll rework")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/00344d60f8b18907171178d7cf598de71d127b0b.1668710222.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2022-11-17 18:40:15 +00:00 committed by Jens Axboe
parent b98186aee2
commit 539bcb57da
1 changed files with 7 additions and 0 deletions
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7
io_uring/poll.c
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@ -228,6 +228,13 @@ static int io_poll_check_events(struct io_kiocb *req, bool *locked)
return IOU_POLL_DONE;
if (v & IO_POLL_CANCEL_FLAG)
return -ECANCELED;
/*
* cqe.res contains only events of the first wake up
* and all others are be lost. Redo vfs_poll() to get
* up to date state.
*/
if ((v & IO_POLL_REF_MASK) != 1)
req->cqe.res = 0;
/* the mask was stashed in __io_poll_execute */
if (!req->cqe.res) {