[PATCH liburing 1/1] man/io_uring_enter.2: notes about cqe-skip & drain interoperability

[Pavel Begunkov <asml.silence@gmail.com>]

IOSQE_CQE_SKIP_SUCCESS can't be used together with draining in a single
ring, add a paragraph explaining what are the restrictions.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 man/io_uring_enter.2 | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/man/io_uring_enter.2 b/man/io_uring_enter.2
index b003e05..871cbce 100644
--- a/man/io_uring_enter.2
+++ b/man/io_uring_enter.2
@@ -1115,6 +1115,15 @@ CQEs in cases where the side effects of a successfully executed operation is
 enough for userspace to know the state of the system. One such example would
 be writing to a synchronisation file.
 
+It also doesn't work with
+.B IOSQE_IO_DRAIN.
+Using both of them in a ring is undefined behaviour even when they never appear
+together in a single request. Currently, after first request with
+.B IOSQE_CQE_SKIP_SUCCESS,
+all subsequent requests marked for drain will be failed. However, the
+error reporting is best effort only and restrictions may change in
+the future.
+
 Available since 5.17.
 
 .PP
-- 
2.34.0