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io_uring: don't set COMP_LOCKED if won't put 

__io_kill_linked_timeout() sets REQ_F_COMP_LOCKED for a linked timeout
even if it can't cancel it, e.g. it's already running. It not only races
with io_link_timeout_fn() for ->flags field, but also leaves the flag
set and so io_link_timeout_fn() may find it and decide that it holds the
lock. Hopefully, the second problem is potential.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2020-10-13 09:43:56 +01:00 committed by Jens Axboe
parent 035fbafc7a
commit 368c5481ae
1 changed files with 1 additions and 1 deletions
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2
fs/io_uring.c
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@ -1769,6 +1769,7 @@ static bool io_link_cancel_timeout(struct io_kiocb *req)
ret = hrtimer_try_to_cancel(&io->timer);
if (ret != -1) {
req->flags |= REQ_F_COMP_LOCKED;
io_cqring_fill_event(req, -ECANCELED);
io_commit_cqring(ctx);
req->flags &= ~REQ_F_LINK_HEAD;
@ -1791,7 +1792,6 @@ static bool __io_kill_linked_timeout(struct io_kiocb *req)
return false;
list_del_init(&link->link_list);
link->flags |= REQ_F_COMP_LOCKED;
wake_ev = io_link_cancel_timeout(link);
req->flags &= ~REQ_F_LINK_TIMEOUT;
return wake_ev;