int event_ust_enable_tracepoint(struct ltt_ust_session *usess,
struct ltt_ust_channel *uchan, struct lttng_event *event,
char *filter_expression,
int event_ust_enable_tracepoint(struct ltt_ust_session *usess,
struct ltt_ust_channel *uchan, struct lttng_event *event,
char *filter_expression,