[PATCH] io_uring: net: fix bug of completing multishot accept twice

[Hao Xu <hao.xu@linux.dev>]

From: Hao Xu <howeyxu@tencent.com>

Now that we use centralized completion in io_issue_sqe, we should skip
that for multishot accept requests since we complete them in the
specific op function.

Fixes: 34106529422e ("io_uring: never defer-complete multi-apoll")
Signed-off-by: Hao Xu <howeyxu@tencent.com>
---

I retrieved the history:

in 4e86a2c98013 ("io_uring: implement multishot mode for accept")
we add the multishot accept, it repeatly completes cqe in io_accept()
until get -EAGAIN [1], then it returns 0 to io_issue_sqe().
io_issue_sqe() does nothing to it then.

in 09eaa49e078c ("io_uring: handle completions in the core")
we add __io_req_complete() for IOU_OK in io_issue_sqe(). This causes at
[1], we do call __io_req_complete().But since IO_URING_F_COMPLETE_DEFER
is set, it does nothing.

in 34106529422e ("io_uring: never defer-complete multi-apoll")
we remove IO_URING_F_COMPLETE_DEFER, but unluckily the multishot accept
test is broken, we didn't find the error.

So it just has infuence to for-5.20, I'll update the liburing test
today.

 io_uring/net.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/io_uring/net.c b/io_uring/net.c
index 207803758222..5097df5b2c46 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -630,7 +630,7 @@ int io_accept(struct io_kiocb *req, unsigned int issue_flags)
 			 */
 			if ((req->flags & IO_APOLL_MULTI_POLLED) ==
 			    IO_APOLL_MULTI_POLLED)
-				ret = 0;
+				ret = IOU_ISSUE_SKIP_COMPLETE;
 			return ret;
 		}
 		if (ret == -ERESTARTSYS)

base-commit: 0efaf0d19e9e1271f2275393e62f709907cd40e2
-- 
2.25.1