From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Tue, 29 Oct 2019 03:29:53 +0000 (-0400)
Subject: Fix: relayd: live: some listed sessions are not attacheable
X-Git-Tag: v2.12.0-rc1~271
X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=commitdiff_plain;h=d995f382e348c509c15673aba195c3ecb624391c

Fix: relayd: live: some listed sessions are not attacheable

The list sessions command currently returns sessions that do not
have a current trace chunk. This can be caused by the session
either being destroyed or being so young that it hasn't had a
trace chunk created against it yet.

In both cases, such sessions would not be attacheable in their
current condition. This fix omits them from from the listing
to reduce the number of failures at the "attach session" and
"attach stream" step.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/src/bin/lttng-relayd/live.c b/src/bin/lttng-relayd/live.c
index 74c28a457..8c4f501aa 100644
--- a/src/bin/lttng-relayd/live.c
+++ b/src/bin/lttng-relayd/live.c
@@ -831,9 +831,18 @@ int viewer_list_sessions(struct relay_connection *conn)
 
 		health_code_update();
 
+		pthread_mutex_lock(&session->lock);
 		if (session->connection_closed) {
 			/* Skip closed session */
-			continue;
+			goto next_session;
+		}
+		if (!session->current_trace_chunk) {
+			/*
+			 * Skip un-attachable session. It is either
+			 * being destroyed or has not had a trace
+			 * chunk created against it yet.
+			 */
+			goto next_session;
 		}
 
 		if (count >= buf_count) {
@@ -844,7 +853,7 @@ int viewer_list_sessions(struct relay_connection *conn)
 				new_buf_count * sizeof(*send_session_buf));
 			if (!newbuf) {
 				ret = -1;
-				break;
+				goto break_loop;
 			}
 			send_session_buf = newbuf;
 			buf_count = new_buf_count;
@@ -854,12 +863,12 @@ int viewer_list_sessions(struct relay_connection *conn)
 				session->session_name,
 				sizeof(send_session->session_name))) {
 			ret = -1;
-			break;
+			goto break_loop;
 		}
 		if (lttng_strncpy(send_session->hostname, session->hostname,
 				sizeof(send_session->hostname))) {
 			ret = -1;
-			break;
+			goto break_loop;
 		}
 		send_session->id = htobe64(session->id);
 		send_session->live_timer = htobe32(session->live_timer);
@@ -870,6 +879,12 @@ int viewer_list_sessions(struct relay_connection *conn)
 		}
 		send_session->streams = htobe32(session->stream_count);
 		count++;
+	next_session:
+		pthread_mutex_unlock(&session->lock);
+		continue;
+	break_loop:
+		pthread_mutex_unlock(&session->lock);
+		break;
 	}
 	rcu_read_unlock();
 	if (ret < 0) {