X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Fcmd.c;h=2a61eee064f5af2fa558e73db87f2057fd8eb120;hb=1148bd3a82f9819f3e59b9ce2b3adc139de9db45;hp=cca25992313cd8c48f5f049d717cff73e6a41045;hpb=92d28f51315353f6c9085de290e06f0e30c2b1ef;p=lttng-tools.git

diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
index cca259923..2a61eee06 100644
--- a/src/bin/lttng-sessiond/cmd.c
+++ b/src/bin/lttng-sessiond/cmd.c
@@ -1583,6 +1583,7 @@ 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;
 
@@ -1598,6 +1599,21 @@ 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 */