bonding: clean muticast addresses when device changes type

Bonding device forbids slave device of different types under the same
master.

However, it is possible for a bonding master to change type during its
lifetime.  This can be either from ARPHRD_ETHER to ARPHRD_INFINIBAND
or the other way arround.  The change of type requires device level
multicast address cleanup because device level multicast addresses
depend on the device type.

The patch adds a call to dev_close() before the bonding master changes
type and dev_open() just after that.

In the example below I enslaved an IPoIB device (ib0) under
bond0. Since each bonding master starts as device of type ARPHRD_ETHER
by default, a change of type occurs when ib0 is enslaved.

This is how /proc/net/dev_mcast looks like without the patch

5    bond0           1     0     00ffffffff12601bffff000000000001ff96ca05
5    bond0           1     0     01005e000116
5    bond0           1     0     01005e7ffffd
5    bond0           1     0     01005e000001
5    bond0           1     0     333300000001
6    ib0             1     0     00ffffffff12601bffff000000000001ff96ca05
6    ib0             1     0     333300000001
6    ib0             1     0     01005e000001
6    ib0             1     0     01005e7ffffd
6    ib0             1     0     01005e000116
6    ib0             1     0     00ffffffff12401bffff00000000000000000001
6    ib0             1     0     00ffffffff12601bffff00000000000000000001

and this is how it looks like after the patch.

5    bond0           1     0     00ffffffff12601bffff000000000001ff96ca05
5    bond0           1     0     00ffffffff12601bffff00000000000000000001
5    bond0           1     0     00ffffffff12401bffff0000000000000ffffffd
5    bond0           1     0     00ffffffff12401bffff00000000000000000116
5    bond0           1     0     00ffffffff12401bffff00000000000000000001
6    ib0             1     0     00ffffffff12601bffff000000000001ff96ca05
6    ib0             1     0     00ffffffff12401bffff00000000000000000116
6    ib0             1     0     00ffffffff12401bffff0000000000000ffffffd
6    ib0             2     0     00ffffffff12401bffff00000000000000000001
6    ib0             2     0     00ffffffff12601bffff00000000000000000001
Signed-off-by: Moni Shoua <monis@voltaire.com>
Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_main.c

@@ -1459,8 +1459,16 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 	 * ether type (eg ARPHRD_ETHER and ARPHRD_INFINIBAND) share the same bond
 	 */
 	if (bond->slave_cnt == 0) {
+		if (bond_dev->type != slave_dev->type) {
+			dev_close(bond_dev);
+			pr_debug("%s: change device type from %d to %d\n",
+				bond_dev->name, bond_dev->type, slave_dev->type);
 			if (slave_dev->type != ARPHRD_ETHER)
 				bond_setup_by_slave(bond_dev, slave_dev);
+			else
+				ether_setup(bond_dev);
+			dev_open(bond_dev);
+		}
 	} else if (bond_dev->type != slave_dev->type) {
 		pr_err(DRV_NAME ": %s ether type (%d) is different "
 			"from other slaves (%d), can not enslave it.\n",