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;
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 */
ret = ust_app_snapshot_record(usess, output, wait, nb_streams);
if (ret < 0) {
- if (ret == -EINVAL) {
+ switch (-ret) {
+ case EINVAL:
ret = LTTNG_ERR_INVALID;
- goto error_snapshot;
+ break;
+ case ENODATA:
+ ret = LTTNG_ERR_SNAPSHOT_NODATA;
+ break;
+ default:
+ ret = LTTNG_ERR_SNAPSHOT_FAIL;
+ break;
}
-
- ret = LTTNG_ERR_SNAPSHOT_FAIL;
goto error_snapshot;
}