bonding: check return value of nofitier when changing type

This patch adds the possibility to refuse the bonding type change for
other subsystems (such as for example bridge, vlan, etc.)

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 12 insertions, 5 deletions

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 7eeb18751d67..cbe9e353d46a 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1480,8 +1480,15 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
                                  bond_dev->name,
                                  bond_dev->type, slave_dev->type);
 
-                        netdev_bonding_change(bond_dev,
-                                              NETDEV_PRE_TYPE_CHANGE);
+                        res = netdev_bonding_change(bond_dev,
+                                                    NETDEV_PRE_TYPE_CHANGE);
+                        res = notifier_to_errno(res);
+                        if (res) {
+                                pr_err("%s: refused to change device type\n",
+                                       bond_dev->name);
+                                res = -EBUSY;
+                                goto err_undo_flags;
+                        }
 
                         if (slave_dev->type != ARPHRD_ETHER)
                                 bond_setup_by_slave(bond_dev, slave_dev);
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 726ecd1af535..813bed723f58 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2005,7 +2005,7 @@ extern void		__dev_addr_unsync(struct dev_addr_list **to, int *to_count, struct
 extern int              dev_set_promiscuity(struct net_device *dev, int inc);
 extern int              dev_set_allmulti(struct net_device *dev, int inc);
 extern void             netdev_state_change(struct net_device *dev);
-extern void             netdev_bonding_change(struct net_device *dev,
+extern int              netdev_bonding_change(struct net_device *dev,
                                               unsigned long event);
 extern void             netdev_features_change(struct net_device *dev);
 /* Load a device via the kmod */
diff --git a/net/core/dev.c b/net/core/dev.c
index 1a7e1d1d5ad9..d1f027c41e73 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1084,9 +1084,9 @@ void netdev_state_change(struct net_device *dev)
 }
 EXPORT_SYMBOL(netdev_state_change);
 
-void netdev_bonding_change(struct net_device *dev, unsigned long event)
+int netdev_bonding_change(struct net_device *dev, unsigned long event)
 {
-        call_netdevice_notifiers(event, dev);
+        return call_netdevice_notifiers(event, dev);
 }
 EXPORT_SYMBOL(netdev_bonding_change);