releases/3.10.18/xen-netback-don-t-destroy-the-netdev-until-the-vif-is-shut-down.patch

From 410cea5ccb7486942d6d5e0e5bfc65b317c7fdf8 Mon Sep 17 00:00:00 2001
From: Paul Durrant <paul.durrant@citrix.com>
Date: Tue, 8 Oct 2013 14:22:56 +0100
Subject: xen-netback: Don't destroy the netdev until the vif is shut down

From: Paul Durrant <paul.durrant@citrix.com>

[ 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>
---
 drivers/net/xen-netback/common.h    |    1 +
 drivers/net/xen-netback/interface.c |   12 ++++++++++--
 drivers/net/xen-netback/xenbus.c    |   17 ++++++++++++-----
 3 files changed, 23 insertions(+), 7 deletions(-)

--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -115,6 +115,7 @@ struct xenvif *xenvif_alloc(struct devic
 int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
 		   unsigned long rx_ring_ref, unsigned int 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);
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -304,6 +304,9 @@ struct xenvif *xenvif_alloc(struct devic
 	}
 
 	netdev_dbg(dev, "Successfully created xenvif\n");
+
+	__module_get(THIS_MODULE);
+
 	return vif;
 }
 
@@ -369,9 +372,14 @@ void xenvif_disconnect(struct xenvif *vi
 	if (vif->irq)
 		unbind_from_irqhandler(vif->irq, vif);
 
-	unregister_netdev(vif->dev);
-
 	xen_netbk_unmap_frontend_rings(vif);
+}
+
+void xenvif_free(struct xenvif *vif)
+{
+	unregister_netdev(vif->dev);
 
 	free_netdev(vif->dev);
+
+	module_put(THIS_MODULE);
 }
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -42,7 +42,7 @@ static int netback_remove(struct xenbus_
 	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);
@@ -203,9 +203,18 @@ static void disconnect_backend(struct xe
 {
 	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;
 	}
 }
@@ -237,14 +246,11 @@ static void frontend_changed(struct xenb
 	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;
@@ -253,6 +259,7 @@ static void frontend_changed(struct xenb
 		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);