unregister_trace_event
extern int unregister_trace_event(struct trace_event *event);
unregister_trace_event(&trace_blk_event);
unregister_trace_event(&call->event);
unregister_trace_event(&user->call.event);
EXPORT_SYMBOL_GPL(unregister_trace_event);
unregister_trace_event(&call->event);