ring-buffer: Fix ring buffer size in rb_write_something()

'cnt' should be used to calculate ring buffer size rather than data->cnt

Link: http://lkml.kernel.org/r/1537704693-184237-1-git-send-email-yuehaibing@huawei.comSigned-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

kernel/trace/ring_buffer.c

@@ -4979,7 +4979,7 @@ static __init int rb_write_something(struct rb_test_data *data, bool nested)
 	cnt = data->cnt + (nested ? 27 : 0);
 
 	/* Multiply cnt by ~e, to make some unique increment */
-	size = (data->cnt * 68 / 25) % (sizeof(rb_string) - 1);
+	size = (cnt * 68 / 25) % (sizeof(rb_string) - 1);
 
 	len = size + sizeof(struct rb_item);