virtio: console: Don't always create a port 0 if using multiport

If we're using multiport, there's no point in always creating a console
port. Create the console port only if the host doesn't support
multiport.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

drivers/char/virtio_console.c

@@ -784,6 +784,13 @@ int init_port_console(struct port *port)
 	spin_unlock_irq(&pdrvdata_lock);
 	port->guest_connected = true;
 
+	/*
+	 * Start using the new console output if this is the first
+	 * console to come up.
+	 */
+	if (early_put_chars)
+		early_put_chars = NULL;
+
 	/* Notify host of port being opened */
 	send_control_msg(port, VIRTIO_CONSOLE_PORT_OPEN, 1);
 
@@ -1058,14 +1065,8 @@ static void handle_control_message(struct ports_device *portdev,
 	switch (cpkt->event) {
 	case VIRTIO_CONSOLE_PORT_ADD:
 		if (port) {
-			/*
-			 * This can happen for port 0: we have to
-			 * create a console port during probe() as was
-			 * the behaviour before the MULTIPORT feature.
-			 * On a newer host, when the host tells us
-			 * that a port 0 is available, we should just
-			 * say we have the port all set up.
-			 */
+			dev_dbg(&portdev->vdev->dev,
+				"Port %u already added\n", port->id);
 			send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1);
 			break;
 		}
@@ -1409,17 +1410,14 @@ static int __devinit virtcons_probe(struct virtio_device *vdev)
 			err = -ENOMEM;
 			goto free_vqs;
 		}
+	} else {
+		/*
+		 * For backward compatibility: Create a console port
+		 * if we're running on older host.
+		 */
+		add_port(portdev, 0);
 	}
 
-	/*
-	 * For backward compatibility: if we're running on an older
-	 * host, we always want to create a console port.
-	 */
-	add_port(portdev, 0);
-
-	/* Start using the new console output. */
-	early_put_chars = NULL;
-
 	__send_control_msg(portdev, VIRTIO_CONSOLE_BAD_ID,
 			   VIRTIO_CONSOLE_DEVICE_READY, 1);
 	return 0;