[PATCH for-next] io_uring/msg-ring: ensure flags passing works for task_work completions

[Jens Axboe <axboe@kernel.dk>]

If the target ring is using IORING_SETUP_SINGLE_ISSUER and we're posting
a message from a different thread, then we need to ensure that the
fallback task_work that posts the CQE knwos about the flags passing as
well. If not we'll always be posting 0 as the flags.

Fixes: 5ffd63f2b73e ("io_uring/msg_ring: Pass custom flags to the cqe")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

---

diff --git a/io_uring/msg_ring.c b/io_uring/msg_ring.c
index dc233f72a541..5d052d2f3d93 100644
--- a/io_uring/msg_ring.c
+++ b/io_uring/msg_ring.c
@@ -49,11 +49,15 @@ static void io_msg_tw_complete(struct callback_head *head)
 	struct io_msg *msg = container_of(head, struct io_msg, tw);
 	struct io_kiocb *req = cmd_to_io_kiocb(msg);
 	struct io_ring_ctx *target_ctx = req->file->private_data;
+	u32 flags = 0;
 	int ret = 0;
 
+	if (msg->flags & IORING_MSG_RING_FLAGS_PASS)
+		flags = msg->cqe_flags;
+
 	if (current->flags & PF_EXITING)
 		ret = -EOWNERDEAD;
-	else if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0))
+	else if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, flags))
 		ret = -EOVERFLOW;
 
 	if (ret < 0)

-- 
Jens Axboe