Fix: race with the viewer and readiness of streams

[lttng-tools.git] / src / bin / lttng-relayd / live.c

diff --git a/src/bin/lttng-relayd/live.c b/src/bin/lttng-relayd/live.c
index c312e78e976e89bb6949e0aee54cf48e2bdca99c..6864ff4eca19c717c79098b906d54d66ec6562c5 100644 (file)
--- a/src/bin/lttng-relayd/live.c
+++ b/src/bin/lttng-relayd/live.c
@@ -854,7 +854,8 @@ static
 int viewer_attach_session(struct relay_command *cmd,
                struct lttng_ht *sessions_ht)
 {
-       int ret, send_streams = 0, nb_streams = 0;
+       int ret, send_streams = 0;
+       uint32_t nb_streams = 0, nb_streams_ready = 0;
        struct lttng_viewer_attach_session_request request;
        struct lttng_viewer_attach_session_response response;
        struct lttng_viewer_stream send_stream;
@@ -961,14 +962,16 @@ int viewer_attach_session(struct relay_command *cmd,
                        if (stream->session != cmd->session) {
                                continue;
                        }
+                       nb_streams++;
 
                        /*
-                        * Don't send streams with no ctf_trace, they are not ready to be
-                        * read.
+                        * Don't send streams with no ctf_trace, they are not
+                        * ready to be read.
                         */
-                       if (!stream->ctf_trace) {
+                       if (!stream->ctf_trace || !stream->viewer_ready) {
                                continue;
                        }
+                       nb_streams_ready++;
 
                        vstream = live_find_viewer_stream_by_id(stream->stream_handle);
                        if (!vstream) {
@@ -977,7 +980,11 @@ int viewer_attach_session(struct relay_command *cmd,
                                        goto end_unlock;
                                }
                        }
-                       nb_streams++;
+               }
+
+               /* We must have the same amount of existing stream and ready stream. */
+               if (nb_streams != nb_streams_ready) {
+                       nb_streams = 0;
                }
                response.streams_count = htobe32(nb_streams);
        }