virtio: console: Resize console port 0 on config intr only if multiport is off

When using multiport, we'll use control messages. Ensure we don't
accidentally update port 0 size on config interrupts.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
CC: Christian Borntraeger <borntraeger@de.ibm.com>
CC: linuxppc-dev@ozlabs.org
CC: Kusanagi Kouichi <slash@ac.auone-net.jp>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

drivers/char/virtio_console.c

@@ -1319,13 +1319,16 @@ static void config_intr(struct virtio_device *vdev)
 
 	portdev = vdev->priv;
 
-	/*
-	 * We'll use this way of resizing only for legacy support.
-	 * For newer userspace (VIRTIO_CONSOLE_F_MULTPORT+), use
-	 * control messages to indicate console size changes so that
-	 * it can be done per-port
-	 */
-	resize_console(find_port_by_id(portdev, 0));
+	if (!use_multiport(portdev)) {
+		/*
+		 * We'll use this way of resizing only for legacy
+		 * support.  For newer userspace
+		 * (VIRTIO_CONSOLE_F_MULTPORT+), use control messages
+		 * to indicate console size changes so that it can be
+		 * done per-port.
+		 */
+		resize_console(find_port_by_id(portdev, 0));
+	}
 }
 
 static int init_vqs(struct ports_device *portdev)