[PATCH v2 7/7] 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 0e0b3e75010c..7f6b1fd37606 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -737,6 +737,8 @@ static bool io_cqring_event_overflow(struct io_ring_ctx *ctx, u64 user_data,
 	size_t ocq_size = sizeof(struct io_overflow_cqe);
 	bool is_cqe32 = (ctx->flags & IORING_SETUP_CQE32);
 
+	io_lockdep_assert_cq_locked(ctx);
+
 	if (is_cqe32)
 		ocq_size += sizeof(struct io_uring_cqe);
 
-- 
2.49.0