1 files changed, 33 insertions, 44 deletions

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 237eee26fbc3..7671914be172 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1048,7 +1048,7 @@ static void handle_control_message(struct ports_device *portdev,
         cpkt = (struct virtio_console_control *)(buf->buf + buf->offset);
 
         port = find_port_by_id(portdev, cpkt->id);
-        if (!port) {
+        if (!port && cpkt->event != VIRTIO_CONSOLE_PORT_ADD) {
                 /* No valid header at start of buffer.  Drop it. */
                 dev_dbg(&portdev->vdev->dev,
                         "Invalid index %u in control packet\n", cpkt->id);
@@ -1056,6 +1056,30 @@ 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.
+                         */
+                        send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1);
+                        break;
+                }
+                if (cpkt->id >= portdev->config.max_nr_ports) {
+                        dev_warn(&portdev->vdev->dev,
+                                "Request for adding port with out-of-bound id %u, max. supported id: %u\n",
+                                cpkt->id, portdev->config.max_nr_ports - 1);
+                        break;
+                }
+                add_port(portdev, cpkt->id);
+                break;
+        case VIRTIO_CONSOLE_PORT_REMOVE:
+                remove_port(port);
+                break;
         case VIRTIO_CONSOLE_CONSOLE_PORT:
                 if (!cpkt->value)
                         break;
@@ -1114,32 +1138,6 @@ static void handle_control_message(struct ports_device *portdev,
                         kobject_uevent(&port->dev->kobj, KOBJ_CHANGE);
                 }
                 break;
-        case VIRTIO_CONSOLE_PORT_REMOVE:
-                /*
-                 * Hot unplug the port.  We don't decrement nr_ports
-                 * since we don't want to deal with extra complexities
-                 * of using the lowest-available port id: We can just
-                 * pick up the nr_ports number as the id and not have
-                 * userspace send it to us.  This helps us in two
-                 * ways:
-                 *
-                 * - We don't need to have a 'port_id' field in the
-                 *   config space when a port is hot-added.  This is a
-                 *   good thing as we might queue up multiple hotplug
-                 *   requests issued in our workqueue.
-                 *
-                 * - Another way to deal with this would have been to
-                 *   use a bitmap of the active ports and select the
-                 *   lowest non-active port from that map.  That
-                 *   bloats the already tight config space and we
-                 *   would end up artificially limiting the
-                 *   max. number of ports to sizeof(bitmap).  Right
-                 *   now we can support 2^32 ports (as the port id is
-                 *   stored in a u32 type).
-                 *
-                 */
-                remove_port(port);
-                break;
         }
 }
 
@@ -1347,7 +1345,6 @@ static const struct file_operations portdev_fops = {
 static int __devinit virtcons_probe(struct virtio_device *vdev)
 {
         struct ports_device *portdev;
-        u32 i;
         int err;
         bool multiport;
 
@@ -1376,29 +1373,15 @@ static int __devinit virtcons_probe(struct virtio_device *vdev)
         }
 
         multiport = false;
-        portdev->config.nr_ports = 1;
         portdev->config.max_nr_ports = 1;
         if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT)) {
                 multiport = true;
                 vdev->features[0] |= 1 << VIRTIO_CONSOLE_F_MULTIPORT;
 
                 vdev->config->get(vdev, offsetof(struct virtio_console_config,
-                                                 nr_ports),
-                                  &portdev->config.nr_ports,
-                                  sizeof(portdev->config.nr_ports));
-                vdev->config->get(vdev, offsetof(struct virtio_console_config,
                                                  max_nr_ports),
                                   &portdev->config.max_nr_ports,
                                   sizeof(portdev->config.max_nr_ports));
-                if (portdev->config.nr_ports > portdev->config.max_nr_ports) {
-                        dev_warn(&vdev->dev,
-                                 "More ports (%u) specified than allowed (%u). Will init %u ports.",
-                                 portdev->config.nr_ports,
-                                 portdev->config.max_nr_ports,
-                                 portdev->config.max_nr_ports);
-
-                        portdev->config.nr_ports = portdev->config.max_nr_ports;
-                }
         }
 
         /* Let the Host know we support multiple ports.*/
@@ -1428,11 +1411,17 @@ static int __devinit virtcons_probe(struct virtio_device *vdev)
                 }
         }
 
-        for (i = 0; i < portdev->config.nr_ports; i++)
-                add_port(portdev, i);
+        /*
+         * 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;
 
 free_vqs: