xen-netback: handle IPv6 TCP GSO packets from the guest
[cascardo/linux.git] / drivers / net / xen-netback / xenbus.c
index 1fe48fe..02cb00b 100644 (file)
 struct backend_info {
        struct xenbus_device *dev;
        struct xenvif *vif;
+
+       /* This is the state that will be reflected in xenstore when any
+        * active hotplug script completes.
+        */
+       enum xenbus_state state;
+
        enum xenbus_state frontend_state;
        struct xenbus_watch hotplug_status_watch;
        u8 have_hotplug_status_watch:1;
@@ -33,16 +39,20 @@ static int connect_rings(struct backend_info *);
 static void connect(struct backend_info *);
 static void backend_create_xenvif(struct backend_info *be);
 static void unregister_hotplug_status_watch(struct backend_info *be);
+static void set_backend_state(struct backend_info *be,
+                             enum xenbus_state state);
 
 static int netback_remove(struct xenbus_device *dev)
 {
        struct backend_info *be = dev_get_drvdata(&dev->dev);
 
+       set_backend_state(be, XenbusStateClosed);
+
        unregister_hotplug_status_watch(be);
        if (be->vif) {
                kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
                xenbus_rm(XBT_NIL, dev->nodename, "hotplug-status");
-               xenvif_disconnect(be->vif);
+               xenvif_free(be->vif);
                be->vif = NULL;
        }
        kfree(be);
@@ -95,6 +105,22 @@ static int netback_probe(struct xenbus_device *dev,
                        goto abort_transaction;
                }
 
+               err = xenbus_printf(xbt, dev->nodename, "feature-gso-tcpv6",
+                                   "%d", sg);
+               if (err) {
+                       message = "writing feature-gso-tcpv6";
+                       goto abort_transaction;
+               }
+
+               /* We support partial checksum setup for IPv6 packets */
+               err = xenbus_printf(xbt, dev->nodename,
+                                   "feature-ipv6-csum-offload",
+                                   "%d", 1);
+               if (err) {
+                       message = "writing feature-ipv6-csum-offload";
+                       goto abort_transaction;
+               }
+
                /* We support rx-copy path. */
                err = xenbus_printf(xbt, dev->nodename,
                                    "feature-rx-copy", "%d", 1);
@@ -136,6 +162,8 @@ static int netback_probe(struct xenbus_device *dev,
        if (err)
                goto fail;
 
+       be->state = XenbusStateInitWait;
+
        /* This kicks hotplug scripts, so do it immediately. */
        backend_create_xenvif(be);
 
@@ -208,15 +236,113 @@ static void backend_create_xenvif(struct backend_info *be)
        kobject_uevent(&dev->dev.kobj, KOBJ_ONLINE);
 }
 
+static void backend_disconnect(struct backend_info *be)
+{
+       if (be->vif)
+               xenvif_disconnect(be->vif);
+}
 
-static void disconnect_backend(struct xenbus_device *dev)
+static void backend_connect(struct backend_info *be)
 {
-       struct backend_info *be = dev_get_drvdata(&dev->dev);
+       if (be->vif)
+               connect(be);
+}
 
-       if (be->vif) {
-               xenbus_rm(XBT_NIL, dev->nodename, "hotplug-status");
-               xenvif_disconnect(be->vif);
-               be->vif = NULL;
+static inline void backend_switch_state(struct backend_info *be,
+                                       enum xenbus_state state)
+{
+       struct xenbus_device *dev = be->dev;
+
+       pr_debug("%s -> %s\n", dev->nodename, xenbus_strstate(state));
+       be->state = state;
+
+       /* If we are waiting for a hotplug script then defer the
+        * actual xenbus state change.
+        */
+       if (!be->have_hotplug_status_watch)
+               xenbus_switch_state(dev, state);
+}
+
+/* Handle backend state transitions:
+ *
+ * The backend state starts in InitWait and the following transitions are
+ * allowed.
+ *
+ * InitWait -> Connected
+ *
+ *    ^    \         |
+ *    |     \        |
+ *    |      \       |
+ *    |       \      |
+ *    |        \     |
+ *    |         \    |
+ *    |          V   V
+ *
+ *  Closed  <-> Closing
+ *
+ * The state argument specifies the eventual state of the backend and the
+ * function transitions to that state via the shortest path.
+ */
+static void set_backend_state(struct backend_info *be,
+                             enum xenbus_state state)
+{
+       while (be->state != state) {
+               switch (be->state) {
+               case XenbusStateClosed:
+                       switch (state) {
+                       case XenbusStateInitWait:
+                       case XenbusStateConnected:
+                               pr_info("%s: prepare for reconnect\n",
+                                       be->dev->nodename);
+                               backend_switch_state(be, XenbusStateInitWait);
+                               break;
+                       case XenbusStateClosing:
+                               backend_switch_state(be, XenbusStateClosing);
+                               break;
+                       default:
+                               BUG();
+                       }
+                       break;
+               case XenbusStateInitWait:
+                       switch (state) {
+                       case XenbusStateConnected:
+                               backend_connect(be);
+                               backend_switch_state(be, XenbusStateConnected);
+                               break;
+                       case XenbusStateClosing:
+                       case XenbusStateClosed:
+                               backend_switch_state(be, XenbusStateClosing);
+                               break;
+                       default:
+                               BUG();
+                       }
+                       break;
+               case XenbusStateConnected:
+                       switch (state) {
+                       case XenbusStateInitWait:
+                       case XenbusStateClosing:
+                       case XenbusStateClosed:
+                               backend_disconnect(be);
+                               backend_switch_state(be, XenbusStateClosing);
+                               break;
+                       default:
+                               BUG();
+                       }
+                       break;
+               case XenbusStateClosing:
+                       switch (state) {
+                       case XenbusStateInitWait:
+                       case XenbusStateConnected:
+                       case XenbusStateClosed:
+                               backend_switch_state(be, XenbusStateClosed);
+                               break;
+                       default:
+                               BUG();
+                       }
+                       break;
+               default:
+                       BUG();
+               }
        }
 }
 
@@ -228,42 +354,33 @@ static void frontend_changed(struct xenbus_device *dev,
 {
        struct backend_info *be = dev_get_drvdata(&dev->dev);
 
-       pr_debug("frontend state %s\n", xenbus_strstate(frontend_state));
+       pr_debug("%s -> %s\n", dev->otherend, xenbus_strstate(frontend_state));
 
        be->frontend_state = frontend_state;
 
        switch (frontend_state) {
        case XenbusStateInitialising:
-               if (dev->state == XenbusStateClosed) {
-                       pr_info("%s: prepare for reconnect\n", dev->nodename);
-                       xenbus_switch_state(dev, XenbusStateInitWait);
-               }
+               set_backend_state(be, XenbusStateInitWait);
                break;
 
        case XenbusStateInitialised:
                break;
 
        case XenbusStateConnected:
-               if (dev->state == XenbusStateConnected)
-                       break;
-               backend_create_xenvif(be);
-               if (be->vif)
-                       connect(be);
+               set_backend_state(be, XenbusStateConnected);
                break;
 
        case XenbusStateClosing:
-               if (be->vif)
-                       kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
-               disconnect_backend(dev);
-               xenbus_switch_state(dev, XenbusStateClosing);
+               set_backend_state(be, XenbusStateClosing);
                break;
 
        case XenbusStateClosed:
-               xenbus_switch_state(dev, XenbusStateClosed);
+               set_backend_state(be, XenbusStateClosed);
                if (xenbus_dev_is_online(dev))
                        break;
                /* fall through if not online */
        case XenbusStateUnknown:
+               set_backend_state(be, XenbusStateClosed);
                device_unregister(&dev->dev);
                break;
 
@@ -356,7 +473,9 @@ static void hotplug_status_changed(struct xenbus_watch *watch,
        if (IS_ERR(str))
                return;
        if (len == sizeof("connected")-1 && !memcmp(str, "connected", len)) {
-               xenbus_switch_state(be->dev, XenbusStateConnected);
+               /* Complete any pending state change */
+               xenbus_switch_state(be->dev, be->state);
+
                /* Not interested in this watch anymore. */
                unregister_hotplug_status_watch(be);
        }
@@ -386,12 +505,8 @@ static void connect(struct backend_info *be)
        err = xenbus_watch_pathfmt(dev, &be->hotplug_status_watch,
                                   hotplug_status_changed,
                                   "%s/%s", dev->nodename, "hotplug-status");
-       if (err) {
-               /* Switch now, since we can't do a watch. */
-               xenbus_switch_state(dev, XenbusStateConnected);
-       } else {
+       if (!err)
                be->have_hotplug_status_watch = 1;
-       }
 
        netif_wake_queue(be->vif->dev);
 }
@@ -475,7 +590,12 @@ static int connect_rings(struct backend_info *be)
        if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-no-csum-offload",
                         "%d", &val) < 0)
                val = 0;
-       vif->csum = !val;
+       vif->ip_csum = !val;
+
+       if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-ipv6-csum-offload",
+                        "%d", &val) < 0)
+               val = 0;
+       vif->ipv6_csum = !!val;
 
        /* Map the shared frame, irq etc. */
        err = xenvif_connect(vif, tx_ring_ref, rx_ring_ref,