[PATCH v2 2/7] io_uring: init overflow entry before passing to tracing

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

trace_io_uring_cqe_overflow() doesn't dereference the overflow pointer,
but it's still a good idea to initialise it beforehand if some bpf will
try to poke into it. That will also help to simplifying the tracing
helper in the future.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 io_uring/io_uring.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 2fa84912b053..d112f103135b 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -732,6 +732,16 @@ static bool io_cqring_event_overflow(struct io_ring_ctx *ctx, u64 user_data,
 		ocq_size += sizeof(struct io_uring_cqe);
 
 	ocqe = kmalloc(ocq_size, GFP_ATOMIC | __GFP_ACCOUNT);
+	if (ocqe) {
+		ocqe->cqe.user_data = user_data;
+		ocqe->cqe.res = res;
+		ocqe->cqe.flags = cflags;
+		if (is_cqe32) {
+			ocqe->cqe.big_cqe[0] = extra1;
+			ocqe->cqe.big_cqe[1] = extra2;
+		}
+	}
+
 	trace_io_uring_cqe_overflow(ctx, user_data, res, cflags, ocqe);
 	if (!ocqe) {
 		struct io_rings *r = ctx->rings;
@@ -748,14 +758,6 @@ static bool io_cqring_event_overflow(struct io_ring_ctx *ctx, u64 user_data,
 	if (list_empty(&ctx->cq_overflow_list)) {
 		set_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq);
 		atomic_or(IORING_SQ_CQ_OVERFLOW, &ctx->rings->sq_flags);
-
-	}
-	ocqe->cqe.user_data = user_data;
-	ocqe->cqe.res = res;
-	ocqe->cqe.flags = cflags;
-	if (is_cqe32) {
-		ocqe->cqe.big_cqe[0] = extra1;
-		ocqe->cqe.big_cqe[1] = extra2;
 	}
 	list_add_tail(&ocqe->list, &ctx->cq_overflow_list);
 	return true;
-- 
2.49.0