+ case LTTNG_KERNEL_ENABLE_CHANNEL:
+ {
+ struct ltt_kernel_channel *chan;
+
+ /* Setup lttng message with no payload */
+ ret = setup_lttng_msg(cmd_ctx, 0);
+ if (ret < 0) {
+ goto setup_error;
+ }
+
+ chan = get_kernel_channel_by_name(cmd_ctx->lsm->u.enable.channel_name,
+ cmd_ctx->session->kernel_session);
+ if (chan == NULL) {
+ ret = LTTCOMM_KERN_CHAN_NOT_FOUND;
+ goto error;
+ } else if (chan->enabled == 0) {
+ ret = kernel_enable_channel(chan);
+ if (ret < 0) {
+ if (ret != EEXIST) {
+ ret = LTTCOMM_KERN_CHAN_ENABLE_FAIL;
+ }
+ goto error;
+ }
+ }
+
+ kernel_wait_quiescent(kernel_tracer_fd);
+ ret = LTTCOMM_OK;
+ break;
+ }