Commit a2416e1e authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring: don't halt iopoll too early 



IOPOLL users should care more about getting completions for requests
they submitted, but not in "device did/completed something". Currently,
io_do_iopoll() may return a positive number, which will instruct
io_iopoll_check() to break the loop and end the syscall, even if there
is not enough CQEs or none at all.

Don't return positive numbers, so io_iopoll_check() exits only when it
gets an actual error, need reschedule or got enough CQEs.

Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/641a88f751623b6758303b3171f0a4141f06726e.1628471125.git.asml.silence@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 864ea921

fs/io_uring.c

+6 −9
Original line number Diff line number Diff line
@@ -2288,7 +2288,6 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events, 
	struct io_kiocb *req, *tmp;

	LIST_HEAD(done);

	bool spin;

	int ret;



	/*

	 * Only spin for completions if we don't have multiple devices hanging
@@ -2296,9 +2295,9 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events, 
	 */

	spin = !ctx->poll_multi_queue && *nr_events < min;



	ret = 0;

	list_for_each_entry_safe(req, tmp, &ctx->iopoll_list, inflight_entry) {

		struct kiocb *kiocb = &req->rw.kiocb;

		int ret;



		/*

		 * Move completed and retryable entries to our local lists.
@@ -2313,22 +2312,20 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events, 
			break;



		ret = kiocb->ki_filp->f_op->iopoll(kiocb, spin);

		if (ret < 0)

			break;

		if (unlikely(ret < 0))

			return ret;

		else if (ret)

			spin = false;



		/* iopoll may have completed current req */

		if (READ_ONCE(req->iopoll_completed))

			list_move_tail(&req->inflight_entry, &done);



		if (ret && spin)

			spin = false;

		ret = 0;

	}



	if (!list_empty(&done))

		io_iopoll_complete(ctx, nr_events, &done, resubmit);



	return ret;

	return 0;

}



/*