Fix: load event state (enabled/disabled) correctly

This bug fix is a workaround due to limitations of lttng_disable_event_ext
regarding the disabling of events with similar name but different
characteristics. Although lttng_disable_event_ext provides support for
disabling by name and filter string it does not support exclusion.

The loading of events is cut in 3 phases.

1 - Create all events regardless of their state.
2 - Disable all events.
3 - Enable only the events with the 'enabled' state.

Fixes #959

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/src/common/config/session-config.c b/src/common/config/session-config.c
index 48094c59a427f9636e5b222c09bd85c6b5c3a0d9..743b5143893a4364cf5bf4f314e408102f77824d 100644 (file)
--- a/src/common/config/session-config.c
+++ b/src/common/config/session-config.c
@@ -177,6 +177,11 @@ LTTNG_HIDDEN const char * const config_event_context_preemptible = "PREEMPTIBLE"
 LTTNG_HIDDEN const char * const config_event_context_need_reschedule = "NEED_RESCHEDULE";
 LTTNG_HIDDEN const char * const config_event_context_migratable = "MIGRATABLE";
 
+enum process_event_node_phase {
+       CREATION = 0,
+       ENABLE = 1,
+};
+
 struct consumer_output {
        int enabled;
        char *path;
@@ -1455,9 +1460,9 @@ end:
 
 static
 int process_event_node(xmlNodePtr event_node, struct lttng_handle *handle,
-       const char *channel_name)
+       const char *channel_name, const enum process_event_node_phase phase)
 {
-       int ret, i;
+       int ret = 0, i;
        xmlNodePtr node;
        struct lttng_event event;
        char **exclusions = NULL;
@@ -1708,25 +1713,14 @@ int process_event_node(xmlNodePtr event_node, struct lttng_handle *handle,
                }
        }
 
-       ret = lttng_enable_event_with_exclusions(handle, &event, channel_name,
-                       filter_expression, exclusion_count, exclusions);
-       if (ret) {
-               goto end;
-       }
-
-       if (!event.enabled) {
-               /*
-                * Note that we should use lttng_disable_event_ext() (2.6+) to
-                * eliminate the risk of clashing on events of the same
-                * name (with different event types and loglevels).
-                *
-                * Unfortunately, lttng_disable_event_ext() only performs a
-                * match on the name and event type and errors out if any other
-                * event attribute is not set to its default value.
-                *
-                * This will disable all events that match this name.
-                */
-               ret = lttng_disable_event(handle, event.name, channel_name);
+       if ((event.enabled && phase == ENABLE) || phase == CREATION) {
+               ret = lttng_enable_event_with_exclusions(handle, &event, channel_name,
+                               filter_expression, exclusion_count, exclusions);
+               if (ret < 0) {
+                       WARN("Enabling event (name:%s) on load failed.", event.name);
+                       ret = -LTTNG_ERR_LOAD_INVALID_CONFIG;
+                       goto end;
+               }
        }
 end:
        for (i = 0; i < exclusion_count; i++) {
@@ -1743,6 +1737,7 @@ int process_events_node(xmlNodePtr events_node, struct lttng_handle *handle,
        const char *channel_name)
 {
        int ret = 0;
+       struct lttng_event event;
        xmlNodePtr node;
 
        assert(events_node);
@@ -1751,11 +1746,33 @@ int process_events_node(xmlNodePtr events_node, struct lttng_handle *handle,
 
        for (node = xmlFirstElementChild(events_node); node;
                node = xmlNextElementSibling(node)) {
-               ret = process_event_node(node, handle, channel_name);
+               ret = process_event_node(node, handle, channel_name, CREATION);
                if (ret) {
                        goto end;
                }
        }
+
+       /*
+        * Disable all events to enable only the necessary events.
+        * Limitations regarding lttng_disable_events and tuple descriptor
+        * force this approach.
+        */
+       memset(&event, 0, sizeof(event));
+       event.loglevel = -1;
+       event.type = LTTNG_EVENT_ALL;
+       ret = lttng_disable_event_ext(handle, &event, channel_name, NULL);
+       if (ret) {
+               goto end;
+       }
+
+       for (node = xmlFirstElementChild(events_node); node;
+                       node = xmlNextElementSibling(node)) {
+               ret = process_event_node(node, handle, channel_name, ENABLE);
+               if (ret) {
+                       goto end;
+               }
+       }
+
 end:
        return ret;
 }