X-Git-Url: http://git.efficios.com/?a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Faction-executor.c;h=a259933521517c358bd2ab2aa9be32b53c1f8756;hb=e1bbf98908a6399f39a9a8bc95bd8b59cecaa816;hp=9a89865a930c142e395f134d6fb23303b3d3508d;hpb=0efb2ad7fc448283184e43d6fb0915febae45384;p=lttng-tools.git

diff --git a/src/bin/lttng-sessiond/action-executor.c b/src/bin/lttng-sessiond/action-executor.c
index 9a89865a9..a25993352 100644
--- a/src/bin/lttng-sessiond/action-executor.c
+++ b/src/bin/lttng-sessiond/action-executor.c
@@ -135,7 +135,7 @@ static int action_executor_snapshot_session_handler(
 		struct action_executor *executor,
 		const struct action_work_item *,
 		struct action_work_subitem *);
-static int action_executor_group_handler(struct action_executor *executor,
+static int action_executor_list_handler(struct action_executor *executor,
 		const struct action_work_item *,
 		struct action_work_subitem *);
 static int action_executor_generic_handler(struct action_executor *executor,
@@ -148,7 +148,7 @@ static const action_executor_handler action_executors[] = {
 	[LTTNG_ACTION_TYPE_STOP_SESSION] = action_executor_stop_session_handler,
 	[LTTNG_ACTION_TYPE_ROTATE_SESSION] = action_executor_rotate_session_handler,
 	[LTTNG_ACTION_TYPE_SNAPSHOT_SESSION] = action_executor_snapshot_session_handler,
-	[LTTNG_ACTION_TYPE_GROUP] = action_executor_group_handler,
+	[LTTNG_ACTION_TYPE_LIST] = action_executor_list_handler,
 };
 
 /* Forward declaration */
@@ -660,11 +660,11 @@ end:
 	return ret;
 }
 
-static int action_executor_group_handler(struct action_executor *executor,
+static int action_executor_list_handler(struct action_executor *executor,
 		const struct action_work_item *work_item,
 		struct action_work_subitem *item)
 {
-	ERR("Execution of a group action by the action executor should never occur");
+	ERR("Execution of a list action by the action executor should never occur");
 	abort();
 }
 
@@ -1010,7 +1010,7 @@ static int add_action_to_subitem_array(struct lttng_action *action,
 	assert(action);
 	assert(subitems);
 
-	if (type == LTTNG_ACTION_TYPE_GROUP) {
+	if (type == LTTNG_ACTION_TYPE_LIST) {
 		unsigned int count, i;
 
 		status = lttng_action_list_get_count(action, &count);
@@ -1031,7 +1031,7 @@ static int add_action_to_subitem_array(struct lttng_action *action,
 
 		/*
 		 * Go directly to the end since there is no need to add the
-		 * group action by itself to the subitems array.
+		 * list action by itself to the subitems array.
 		 */
 		goto end;
 	}
@@ -1060,7 +1060,7 @@ static int add_action_to_subitem_array(struct lttng_action *action,
 				action, &session_name);
 		assert(status == LTTNG_ACTION_STATUS_OK);
 		break;
-	case LTTNG_ACTION_TYPE_GROUP:
+	case LTTNG_ACTION_TYPE_LIST:
 	case LTTNG_ACTION_TYPE_UNKNOWN:
 		/* Fallthrough */
 	default:
@@ -1076,17 +1076,26 @@ static int add_action_to_subitem_array(struct lttng_action *action,
 	 * simplicity and consistency.
 	 */
 	if (session_name != NULL) {
-		struct ltt_session *session = NULL;
+		uint64_t session_id;
 
-		session_lock_list();
-		session = session_find_by_name(session_name);
-		if (session) {
+		/*
+		 * Instantaneous sampling of the session id if present.
+		 *
+		 * This method is preferred over `sessiond_find_by_name` then
+		 * fetching the session'd id since `sessiond_find_by_name`
+		 * requires the session list lock to be taken.
+		 *
+		 * Taking the session list lock can lead to a deadlock
+		 * between the action executor and the notification thread
+		 * (caller of add_action_to_subitem_array). It is okay if the
+		 * session state changes between the enqueuing time and the
+		 * execution time. The execution context is validated at
+		 * execution time.
+		 */
+		if (sample_session_id_by_name(session_name, &session_id)) {
 			LTTNG_OPTIONAL_SET(&subitem.context.session_id,
-					session->id);
-			session_put(session);
+					session_id);
 		}
-
-		session_unlock_list();
 	}
 
 	/* Get a reference to the action. */