io_uring/msg: initialise msg request opcode

It's risky to have msg request opcode set to garbage, so at least
initialise it to nop. Later we might want to add a user inaccessible
opcode for such cases.

Signed-off-by: Pavel Begunkov <[email protected]>
Link: https://lore.kernel.org/r/9afe650fcb348414a4529d89f52eb8969ba06efd.1743190078.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <[email protected]>

Author: isilence

io_uring/msg_ring.c

@@ -93,6 +93,7 @@ static int io_msg_remote_post(struct io_ring_ctx *ctx, struct io_kiocb *req,
 		kmem_cache_free(req_cachep, req);
 		return -EOWNERDEAD;
 	}
+	req->opcode = IORING_OP_NOP;
 	req->cqe.user_data = user_data;
 	io_req_set_res(req, res, cflags);
 	percpu_ref_get(&ctx->refs);