[PATCH 4/4] io_uring: add lockdep warning for overflow posting

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

io_cqring_event_overflow() must be called in the same CQ protection
section as the preceding io_get_cqe(), otherwise overflowed and normal
CQEs can get out of order. It's hard to debug check that exactly, but we
can verify that io_cqring_event_overflow() is called with the CQ locked,
which should be good enough to catch most cases of misuse.

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

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 927d8e45dbdb..da1075b66a87 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -754,6 +754,8 @@ static bool io_cqring_event_overflow(struct io_ring_ctx *ctx, bool locked,
 	gfp_t gfp = GFP_KERNEL_ACCOUNT;
 	bool queued;
 
+	io_lockdep_assert_cq_locked(ctx);
+
 	if (is_cqe32)
 		ocq_size += sizeof(struct io_uring_cqe);
 	if (locked)
-- 
2.49.0