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Re: [Xen-devel] xen-netback notify DomU to send ARP.

On 2013-1-9 18:06, Jan Beulich wrote:
On 09.01.13 at 08:39, jianhai luan <jianhai.luan@xxxxxxxxxx> wrote:
@@ -34,11 +35,42 @@ 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);

+#define nb_to_backend(nb) container_of(nb, struct backend_info, vif_notifier)
+ * When network condition of vif change, notify the frontend.
+ */
+static int netback_netdev_event(struct notifier_block *this,
+                               unsigned long event, void *ptr)
+       struct net_device *event_dev = (struct net_device *)ptr;
Pointless cast.

+       struct backend_info *be = nb_to_backend(this);
+       pr_debug("event_dev: %s, event: %lx\n",
+                event_dev ? event_dev->name : "None", event);
+       if (!be->vif)
+               goto out;
+       switch (event) {
+               /* Notify frontend to Send gratuitous ARP */
+               xenbus_switch_state(be->dev, XenbusStateInitialised);
+               xenbus_switch_state(be->dev, );
This is the sort of change that clearly isn't acceptable, as I don't
think you have ways to check _all_ existing frontends for their
compatibility with this. A connected -> connected transition
might be acceptable (that was done in the block frontend too, for
implementing dynamic resize), but will likely need to be
accompanied by a frontend side patch to handle that (which so
far should be a no-op).
The latest xen net-frontent driver have handled the condition. State XenbusStateInitialised will do nothing, but change to XenbusStateConnected will trigger netdev_notify_peers(netdev) to send ARP.

+               break;
+       default:
+               break;
Pointless default case.

+       }
I don't think you really need the label (and the goto above) - just
put a return there.

+       return NOTIFY_DONE;
static int netback_remove(struct xenbus_device *dev)
        struct backend_info *be = dev_get_drvdata(&dev->dev);

+       unregister_netdevice_notifier(&be->vif_notifier);
        if (be->vif) {
                kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
                xenbus_rm(XBT_NIL, dev->nodename, "hotplug-status");
@@ -129,6 +161,10 @@ static int netback_probe(struct xenbus_device *dev,
        /* This kicks hotplug scripts, so do it immediately. */

+       /*   Event Notify */
+       (be->vif_notifier).notifier_call = netback_netdev_event;
Pointless parentheses.


+       register_netdevice_notifier(&be->vif_notifier);
        return 0;


Attachment: 0001-xen-netback-notify-DomU-to-send-ARP.patch
Description: Text document

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