Clarify empty string/NULL filter errors

[lttng-tools.git] / include / lttng / lttng.h

diff --git a/include/lttng/lttng.h b/include/lttng/lttng.h
index c6fc60558ae833a5fe011147d24ec75f10b20b5c..515e07c4e9703653c600e633d887ccae6f194957 100644 (file)
--- a/include/lttng/lttng.h
+++ b/include/lttng/lttng.h
@@ -516,6 +516,8 @@ extern int lttng_enable_event(struct lttng_handle *handle,
  * If event_name is NULL, all events are enabled with that filter.
  * If channel_name is NULL, the default channel is used (channel0) and created
  * if not found.
+ * If filter_expression is NULL, an event without associated filter is
+ * created.
  */
 extern int lttng_enable_event_with_filter(struct lttng_handle *handle,
                struct lttng_event *event, const char *channel_name,