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>

1 files changed, 10 insertions, 16 deletions

diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 77fee1d51fb2..01bb854c7f62 100644
--- 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);
 }