Commit ceff5017 authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring: don't race double poll setting REQ_F_ASYNC_DATA 



Just as with io_poll_double_prepare() setting REQ_F_DOUBLE_POLL, we can
race with the first poll entry when setting REQ_F_ASYNC_DATA. Move it
under io_poll_double_prepare().

Fixes: a18427bb2d9b ("io_uring: optimise submission side poll_refs")
Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/df6920f509c11115aa2bce8b34dc5fdb0eb98920.1657203020.git.asml.silence@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 7a121ced

io_uring/poll.c

+3 −3
Original line number Diff line number Diff line
@@ -410,6 +410,8 @@ static void io_poll_double_prepare(struct io_kiocb *req) 
		spin_lock_irq(&head->lock);



	req->flags |= REQ_F_DOUBLE_POLL;

	if (req->opcode == IORING_OP_POLL_ADD)

		req->flags |= REQ_F_ASYNC_DATA;



	if (head)

		spin_unlock_irq(&head->lock);
@@ -448,13 +450,11 @@ static void __io_queue_proc(struct io_poll *poll, struct io_poll_table *pt, 
			return;

		}



		io_poll_double_prepare(req);

		/* mark as double wq entry */

		wqe_private |= IO_WQE_F_DOUBLE;

		io_init_poll_iocb(poll, first->events, first->wait.func);

		io_poll_double_prepare(req);

		*poll_ptr = poll;

		if (req->opcode == IORING_OP_POLL_ADD)

			req->flags |= REQ_F_ASYNC_DATA;

	} else {

		/* fine to modify, there is no poll queued to race with us */

		req->flags |= REQ_F_SINGLE_POLL;