bonding: fix panic on non-ARPHRD_ETHER enslave failure

commit 40baec22 upstream.

Since commit 7d5cd2ce529b, when bond_enslave fails on devices that
are not ARPHRD_ETHER, if needed, it resets the bonding device back to
ARPHRD_ETHER by calling ether_setup.

	Unfortunately, ether_setup clobbers dev->flags, clearing IFF_UP
if the bond device is up, leaving it in a quasi-down state without
having actually gone through dev_close.  For bonding, if any periodic
work queue items are active (miimon, arp_interval, etc), those will
remain running, as they are stopped by bond_close.  At this point, if
the bonding module is unloaded or the bond is deleted, the system will
panic when the work function is called.

	This panic is resolved by calling dev_close on the bond itself
prior to calling ether_setup.

Cc: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: Jay Vosburgh <jay.vosburgh@canonical.com>
Fixes: 7d5cd2ce ("bonding: correctly handle bonding type change on enslave failure")
Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/net/bonding/bond_main.c

@@ -1667,6 +1667,7 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 					    slave_dev->dev_addr))
 			eth_hw_addr_random(bond_dev);
 		if (bond_dev->type != ARPHRD_ETHER) {
+			dev_close(bond_dev);
 			ether_setup(bond_dev);
 			bond_dev->flags |= IFF_MASTER;
 			bond_dev->priv_flags &= ~IFF_TX_SKB_SHARING;