unregister_netdevice : move RTM_DELLINK to until after ndo_uninit

This patch fixes ordering of rtnl notifications during unregister_netdevice
by moving RTM_DELLINK notification to until after ndo_uninit.

The problem was seen with unregistering bond netdevices.

bond ndo_uninit callback generates a few RTM_NEWLINK notifications for
NETDEV_CHANGEADDR and NETDEV_FEAT_CHANGE. This is seen mostly when the
bond is deleted with slaves still enslaved to the bond.

During unregister netdevice (rollback_registered_many to be specific)
bond ndo_uninit is called after RTM_DELLINK notification goes out.
This results in userspace seeing RTM_DELLINK followed by a couple of
RTM_NEWLINK's.

In userspace problem was seen with libnl. libnl cache deletes the bond
when it sees RTM_DELLINK and re-adds the bond with the following
RTM_NEWLINK. Resulting in a stale bond entry in libnl cache when the kernel
has already deleted the bond.

This patch has been tested for bond, bridges and vlan devices.

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/dev.c b/net/core/dev.c
index 11d70e3afefa467ceb64fccd3fad436b6abb9189..fe0b9cd69cb6e3ccf75d665d4981510b6d08041c 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5606,10 +5606,6 @@ static void rollback_registered_many(struct list_head *head)
                */
                call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
 
-               if (!dev->rtnl_link_ops ||
-                   dev->rtnl_link_state == RTNL_LINK_INITIALIZED)
-                       rtmsg_ifinfo(RTM_DELLINK, dev, ~0U, GFP_KERNEL);
-
                /*
                 *      Flush the unicast and multicast chains
                 */
@@ -5619,6 +5615,10 @@ static void rollback_registered_many(struct list_head *head)
                if (dev->netdev_ops->ndo_uninit)
                        dev->netdev_ops->ndo_uninit(dev);
 
+               if (!dev->rtnl_link_ops ||
+                   dev->rtnl_link_state == RTNL_LINK_INITIALIZED)
+                       rtmsg_ifinfo(RTM_DELLINK, dev, ~0U, GFP_KERNEL);
+
                /* Notifier chain MUST detach us all upper devices. */
                WARN_ON(netdev_has_any_upper_dev(dev));