io_uring: add IOU_STOP_MULTISHOT return code

For multishot we want a way to signal the caller that multishot has ended
but also this might not be an error return.

For example sockets return 0 when closed, which should end a multishot
recv, but still have a CQE with result 0

Introduce IOU_STOP_MULTISHOT which does this and indicates that the return
code is stored inside req->cqe

Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220630091231.1456789-7-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 7 insertions, 0 deletions

diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h
index f77e4a5403e4..e8da70781fa3 100644
--- a/io_uring/io_uring.h
+++ b/io_uring/io_uring.h
@@ -15,6 +15,13 @@
 enum {
 	IOU_OK			= 0,
 	IOU_ISSUE_SKIP_COMPLETE	= -EIOCBQUEUED,
+
+	/*
+	 * Intended only when both REQ_F_POLLED and REQ_F_APOLL_MULTISHOT
+	 * are set to indicate to the poll runner that multishot should be
+	 * removed and the result is set on req->cqe.res.
+	 */
+	IOU_STOP_MULTISHOT	= -ECANCELED,
 };
 
 struct io_uring_cqe *__io_get_cqe(struct io_ring_ctx *ctx);