Fix: relayd: connection abruptly closed on viewer stream creation failure

Commit fe88e5175 explains (and fixes) an issue that could cause the
creation of viewer streams to fail. Currently, the error path causes the
relay daemon to abruptly close the connection to its live viewer peer.
This behaviour makes it impossible for the viewer to determine if an
error occurred or if the network connection simply failed.

Returning an `LTTNG_VIEWER_NEW_STREAMS_ERR` status code allows the
viewer to report a precise error. The viewer connection is closed since
the internal error is unlikely to be recoverable.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I557a8b66c1bd1c0bf361cfbabe962d8a6808f4f4

diff --git a/src/bin/lttng-relayd/live.c b/src/bin/lttng-relayd/live.c
index 7de33d5613f12228111d4415493662b73cb3547a..2c7b00f8ac7bab7ce50423abe97b597c0f7e50f1 100644 (file)
--- a/src/bin/lttng-relayd/live.c
+++ b/src/bin/lttng-relayd/live.c
@@ -1180,7 +1180,12 @@ int viewer_get_new_streams(struct relay_connection *conn)
                        LTTNG_VIEWER_SEEK_BEGINNING, &nb_total, &nb_unsent,
                        &nb_created, &closed);
        if (ret < 0) {
-               goto error_unlock_session;
+               /*
+                * This is caused by an internal error; propagate the negative
+                * 'ret' to close the connection.
+                */
+               response.status = htobe32(LTTNG_VIEWER_NEW_STREAMS_ERR);
+               goto send_reply;
        }
        send_streams = 1;
        response.status = htobe32(LTTNG_VIEWER_NEW_STREAMS_OK);
@@ -1235,10 +1240,6 @@ end_put_session:
        }
 error:
        return ret;
-error_unlock_session:
-       pthread_mutex_unlock(&session->lock);
-       session_put(session);
-       return ret;
 }
 
 /*