From: Glauber de Oliveira Costa <gcosta@redhat.com>
Subject: Re: [PATCH RHEL5] Fix netfront teardown
Date: Thu, 21 Dec 2006 20:57:07 -0200
Bugzilla: 219563
Message-Id: <20061221225707.GA27427@redhat.com>
Changelog: [xen] Fix netfront teardown


On Thu, Dec 21, 2006 at 03:12:40PM -0500, James Morris wrote:
> On Thu, 21 Dec 2006, Glauber de Oliveira Costa wrote:
> 
> > It is crucial that between netif_disconnect_backend() and free_netdev()
> > there is a call to unregister_netdev(). The first triggers carrier
> > watches , that can be handled only after free. unregister_netdev()
> > makes sures that all pending events are handled, so after that, we're
> > safe.
> > 
> > ACKS?
> 
> Ack.

-- 
Glauber de Oliveira Costa
Red Hat Inc.
"Free as in Freedom"

--- linux-2.6.18.x86_64/drivers/xen/netfront/netfront.c.orig	2006-12-21 18:28:42.000000000 -0500
+++ linux-2.6.18.x86_64/drivers/xen/netfront/netfront.c	2006-12-21 18:49:31.000000000 -0500
@@ -232,12 +232,8 @@ static inline grant_ref_t xennet_get_rx_
 static int setup_device(struct xenbus_device *, struct netfront_info *);
 static struct net_device *create_netdev(struct xenbus_device *);
 
-static void netfront_closing(struct xenbus_device *);
-
 static void end_access(int, void *);
 static void netif_disconnect_backend(struct netfront_info *);
-static int open_netdev(struct netfront_info *);
-static void close_netdev(struct netfront_info *);
 static void netif_free(struct netfront_info *);
 
 static int network_connect(struct net_device *);
@@ -282,9 +278,20 @@ static int __devinit netfront_probe(stru
 	info = netdev_priv(netdev);
 	dev->dev.driver_data = info;
 
-	err = open_netdev(info);
-	if (err)
+	err = register_netdev(info->netdev);
+	if (err) {
+		printk(KERN_WARNING "%s: register_netdev err=%d\n",
+		       __FUNCTION__, err);
+		goto fail;
+	}
+
+	err = xennet_sysfs_addif(info->netdev);
+	if (err) {
+		unregister_netdev(info->netdev);
+		printk(KERN_WARNING "%s: add sysfs failed err=%d\n",
+		       __FUNCTION__, err);
 		goto fail;
+	}
 
 	return 0;
 
@@ -294,6 +301,24 @@ static int __devinit netfront_probe(stru
 	return err;
 }
 
+static int __devexit netfront_remove(struct xenbus_device *dev)
+{
+	struct netfront_info *info = dev->dev.driver_data;
+
+	DPRINTK("%s\n", dev->nodename);
+
+	netif_disconnect_backend(info);
+
+	del_timer_sync(&info->rx_refill_timer);
+
+	xennet_sysfs_delif(info->netdev);
+
+	unregister_netdev(info->netdev);
+
+	free_netdev(info->netdev);
+
+	return 0;
+}
 
 /**
  * We are reconnecting to the backend, due to a suspend/resume, or a backend
@@ -518,7 +543,7 @@ static void backend_changed(struct xenbu
 		break;
 
 	case XenbusStateClosing:
-		netfront_closing(dev);
+ 		xenbus_frontend_closed(dev);
 		break;
 	}
 }
@@ -1973,70 +1998,6 @@ inetdev_notify(struct notifier_block *th
 }
 
 
-/* ** Close down ** */
-
-
-/**
- * Handle the change of state of the backend to Closing.  We must delete our
- * device-layer structures now, to ensure that writes are flushed through to
- * the backend.  Once is this done, we can switch to Closed in
- * acknowledgement.
- */
-static void netfront_closing(struct xenbus_device *dev)
-{
-	struct netfront_info *info = dev->dev.driver_data;
-
-	DPRINTK("%s\n", dev->nodename);
-
-	close_netdev(info);
-	xenbus_frontend_closed(dev);
-}
-
-
-static int __devexit netfront_remove(struct xenbus_device *dev)
-{
-	struct netfront_info *info = dev->dev.driver_data;
-
-	DPRINTK("%s\n", dev->nodename);
-
-	netif_disconnect_backend(info);
-	free_netdev(info->netdev);
-
-	return 0;
-}
-
-
-static int open_netdev(struct netfront_info *info)
-{
-	int err;
-	
-	err = register_netdev(info->netdev);
-	if (err) {
-		printk(KERN_WARNING "%s: register_netdev err=%d\n",
-		       __FUNCTION__, err);
-		return err;
-	}
-
-	err = xennet_sysfs_addif(info->netdev);
-	if (err) {
-		unregister_netdev(info->netdev);
-		printk(KERN_WARNING "%s: add sysfs failed err=%d\n",
-		       __FUNCTION__, err);
-		return err;
-	}
-
-	return 0;
-}
-
-static void close_netdev(struct netfront_info *info)
-{
-	del_timer_sync(&info->rx_refill_timer);
-
-	xennet_sysfs_delif(info->netdev);
-	unregister_netdev(info->netdev);
-}
-
-
 static void netif_disconnect_backend(struct netfront_info *info)
 {
 	/* Stop old i/f to prevent errors whilst we rebuild the state. */

--- linux-2.6.18.noarch/drivers/xen/netfront/netfront.c.orig	2007-04-20 16:01:53.000000000 -0400
+++ linux-2.6.18.noarch/drivers/xen/netfront/netfront.c	2007-04-20 16:02:03.000000000 -0400
@@ -2023,7 +2023,6 @@
 
 static void netif_free(struct netfront_info *info)
 {
-	close_netdev(info);
 	netif_disconnect_backend(info);
 	free_netdev(info->netdev);
 }