xen-netback: Don't destroy the netdev until the vif is shut down

[ upstream commit id: 279f438e36c0a70b23b86d2090aeec50155034a9 ]

Without this patch, if a frontend cycles through states Closing
and Closed (which Windows frontends need to do) then the netdev
will be destroyed and requires re-invocation of hotplug scripts
to restore state before the frontend can move to Connected. Thus
when udev is not in use the backend gets stuck in InitWait.

With this patch, the netdev is left alone whilst the backend is
still online and is only de-registered and freed just prior to
destroying the vif (which is also nicely symmetrical with the
netdev allocation and registration being done during probe) so
no re-invocation of hotplug scripts is required.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index 8a4d77ee9c5b61a312c3f2142ffa42fc0671e122..4d9a5e70c992c64e6db0ab0093990947d19e13ad 100644 (file)
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -120,6 +120,7 @@ int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
                   unsigned long rx_ring_ref, unsigned int tx_evtchn,
                   unsigned int rx_evtchn);
 void xenvif_disconnect(struct xenvif *vif);
+void xenvif_free(struct xenvif *vif);
 
 void xenvif_get(struct xenvif *vif);
 void xenvif_put(struct xenvif *vif);

diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 087d2db0389d04efc3368a0ba48a925a3b070124..73336c144d926394b5c43239f2b381a62e2bf601 100644 (file)
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -326,6 +326,9 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
        }
 
        netdev_dbg(dev, "Successfully created xenvif\n");
+
+       __module_get(THIS_MODULE);
+
        return vif;
 }
 
@@ -413,12 +416,6 @@ void xenvif_carrier_off(struct xenvif *vif)
 
 void xenvif_disconnect(struct xenvif *vif)
 {
-       /* Disconnect funtion might get called by generic framework
-        * even before vif connects, so we need to check if we really
-        * need to do a module_put.
-        */
-       int need_module_put = 0;
-
        if (netif_carrier_ok(vif->dev))
                xenvif_carrier_off(vif);
 
@@ -432,18 +429,16 @@ void xenvif_disconnect(struct xenvif *vif)
                        unbind_from_irqhandler(vif->tx_irq, vif);
                        unbind_from_irqhandler(vif->rx_irq, vif);
                }
-               /* vif->irq is valid, we had a module_get in
-                * xenvif_connect.
-                */
-               need_module_put = 1;
        }
 
-       unregister_netdev(vif->dev);
-
        xen_netbk_unmap_frontend_rings(vif);
+}
+
+void xenvif_free(struct xenvif *vif)
+{
+       unregister_netdev(vif->dev);
 
        free_netdev(vif->dev);
 
-       if (need_module_put)
-               module_put(THIS_MODULE);
+       module_put(THIS_MODULE);
 }

diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 1fe48fe364ed919a1f011170949c5cd37f4ad905..a53782ef154078717cbcff039a010e93e559fa58 100644 (file)
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -42,7 +42,7 @@ static int netback_remove(struct xenbus_device *dev)
        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);
@@ -213,9 +213,18 @@ static void disconnect_backend(struct xenbus_device *dev)
 {
        struct backend_info *be = dev_get_drvdata(&dev->dev);
 
+       if (be->vif)
+               xenvif_disconnect(be->vif);
+}
+
+static void destroy_backend(struct xenbus_device *dev)
+{
+       struct backend_info *be = dev_get_drvdata(&dev->dev);
+
        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;
        }
 }
@@ -246,14 +255,11 @@ static void frontend_changed(struct xenbus_device *dev,
        case XenbusStateConnected:
                if (dev->state == XenbusStateConnected)
                        break;
-               backend_create_xenvif(be);
                if (be->vif)
                        connect(be);
                break;
 
        case XenbusStateClosing:
-               if (be->vif)
-                       kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
                disconnect_backend(dev);
                xenbus_switch_state(dev, XenbusStateClosing);
                break;
@@ -262,6 +268,7 @@ static void frontend_changed(struct xenbus_device *dev,
                xenbus_switch_state(dev, XenbusStateClosed);
                if (xenbus_dev_is_online(dev))
                        break;
+               destroy_backend(dev);
                /* fall through if not online */
        case XenbusStateUnknown:
                device_unregister(&dev->dev);