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

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>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index a1977430ddfb9be616a6e97c7cfb4951da2cdd09..5715318d6bab3b4c7905c7c69ee549e39636c6cc 100644 (file)
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -184,6 +184,7 @@ 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);
 
 int xenvif_xenbus_init(void);
 void xenvif_xenbus_fini(void);

diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 77fee1d51fb2fc2cf47b218e9eba0ab4f56a1820..01bb854c7f62bfc281dfdc0081829237f2f843d6 100644 (file)
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -353,6 +353,9 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
        }
 
        netdev_dbg(dev, "Successfully created xenvif\n");
+
+       __module_get(THIS_MODULE);
+
        return vif;
 }
 
@@ -366,8 +369,6 @@ int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
        if (vif->tx_irq)
                return 0;
 
-       __module_get(THIS_MODULE);
-
        err = xenvif_map_frontend_rings(vif, tx_ring_ref, rx_ring_ref);
        if (err < 0)
                goto err;
@@ -452,12 +453,6 @@ 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);
 
@@ -468,23 +463,22 @@ 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;
+               vif->tx_irq = 0;
        }
 
        if (vif->task)
                kthread_stop(vif->task);
 
+       xenvif_unmap_frontend_rings(vif);
+}
+
+void xenvif_free(struct xenvif *vif)
+{
        netif_napi_del(&vif->napi);
 
        unregister_netdev(vif->dev);
 
-       xenvif_unmap_frontend_rings(vif);
-
        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);