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author | Pavel Begunkov <asml.silence@gmail.com> | 2021-05-23 15:48:39 +0100 |
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committer | Jens Axboe <axboe@kernel.dk> | 2021-05-25 19:39:58 -0600 |
commit | 17a91051fe63b40ec651b80097c9fff5b093fdc5 (patch) | |
tree | 2ff23057d8bb5cbbed0b123eb9a8b3dd803c1586 /fs/io-wq.h | |
parent | ba5ef6dc8a827a904794210a227cdb94828e8ae7 (diff) | |
download | linux-17a91051fe63b40ec651b80097c9fff5b093fdc5.tar.gz linux-17a91051fe63b40ec651b80097c9fff5b093fdc5.tar.bz2 linux-17a91051fe63b40ec651b80097c9fff5b093fdc5.zip |
io_uring/io-wq: close io-wq full-stop gap
There is an old problem with io-wq cancellation where requests should be
killed and are in io-wq but are not discoverable, e.g. in @next_hashed
or @linked vars of io_worker_handle_work(). It adds some unreliability
to individual request canellation, but also may potentially get
__io_uring_cancel() stuck. For instance:
1) An __io_uring_cancel()'s cancellation round have not found any
request but there are some as desribed.
2) __io_uring_cancel() goes to sleep
3) Then workers wake up and try to execute those hidden requests
that happen to be unbound.
As we already cancel all requests of io-wq there, set IO_WQ_BIT_EXIT
in advance, so preventing 3) from executing unbound requests. The
workers will initially break looping because of getting a signal as they
are threads of the dying/exec()'ing user task.
Cc: stable@vger.kernel.org
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/abfcf8c54cb9e8f7bfbad7e9a0cc5433cc70bdc2.1621781238.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/io-wq.h')
-rw-r--r-- | fs/io-wq.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/io-wq.h b/fs/io-wq.h index 0e6d310999e8..af2df0680ee2 100644 --- a/fs/io-wq.h +++ b/fs/io-wq.h @@ -122,7 +122,7 @@ struct io_wq_data { }; struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data); -void io_wq_put(struct io_wq *wq); +void io_wq_exit_start(struct io_wq *wq); void io_wq_put_and_exit(struct io_wq *wq); void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work); |