X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Fcmd.c;h=5bf00be8536f12cb124fd0d828486344b75734b7;hp=dc465173e3521984f48b91f23e1782b83ba22b09;hb=cde3e505b7948c15880114268534d21fb1f10a1c;hpb=0210bba27680d0bc4278b926cad8b77eaa1b61ae

diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
index dc465173e..5bf00be85 100644
--- a/src/bin/lttng-sessiond/cmd.c
+++ b/src/bin/lttng-sessiond/cmd.c
@@ -1779,6 +1779,7 @@ error:
 int cmd_start_trace(struct ltt_session *session)
 {
 	int ret;
+	unsigned long nb_chan = 0;
 	struct ltt_kernel_session *ksession;
 	struct ltt_ust_session *usess;
 
@@ -1794,6 +1795,21 @@ int cmd_start_trace(struct ltt_session *session)
 		goto error;
 	}
 
+	/*
+	 * Starting a session without channel is useless since after that it's not
+	 * possible to enable channel thus inform the client.
+	 */
+	if (usess && usess->domain_global.channels) {
+		nb_chan += lttng_ht_get_count(usess->domain_global.channels);
+	}
+	if (ksession) {
+		nb_chan += ksession->channel_count;
+	}
+	if (!nb_chan) {
+		ret = LTTNG_ERR_NO_CHANNEL;
+		goto error;
+	}
+
 	session->enabled = 1;
 
 	/* Kernel tracing */