bond: have random dev address by default instead of zeroes

Makes more sense to have randomly generated address by default than to
have all zeroes. It also allows user to for example put the bond into
bridge without need to have any slaves in it.

Also note that this changes only behaviour of bonds with no slaves. Once
the first slave device is enslaved, its address will be used (no change
here).

Also, fix dev_assign_type values on the way.
Reported-by: Pavel Šimerda <psimerda@redhat.com>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_main.c

@@ -1320,14 +1320,15 @@ static void bond_netpoll_cleanup(struct net_device *bond_dev)
 
 /*---------------------------------- IOCTL ----------------------------------*/
 
-static int bond_sethwaddr(struct net_device *bond_dev,
+static void bond_set_dev_addr(struct net_device *bond_dev,
 			      struct net_device *slave_dev)
 {
 	pr_debug("bond_dev=%p\n", bond_dev);
 	pr_debug("slave_dev=%p\n", slave_dev);
 	pr_debug("slave_dev->addr_len=%d\n", slave_dev->addr_len);
 	memcpy(bond_dev->dev_addr, slave_dev->dev_addr, slave_dev->addr_len);
-	return 0;
+	bond_dev->addr_assign_type = NET_ADDR_SET;
+	call_netdevice_notifiers(NETDEV_CHANGEADDR, bond_dev);
 }
 
 static netdev_features_t bond_fix_features(struct net_device *dev,
@@ -1628,10 +1629,8 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 
 	/* If this is the first slave, then we need to set the master's hardware
 	 * address to be the same as the slave's. */
-	if (is_zero_ether_addr(bond->dev->dev_addr))
-		memcpy(bond->dev->dev_addr, slave_dev->dev_addr,
-		       slave_dev->addr_len);
-
+	if (bond->dev_addr_from_first)
+		bond_set_dev_addr(bond->dev, slave_dev);
 
 	new_slave = kzalloc(sizeof(struct slave), GFP_KERNEL);
 	if (!new_slave) {
@@ -2048,12 +2047,8 @@ int bond_release(struct net_device *bond_dev, struct net_device *slave_dev)
 
 	if (bond->slave_cnt == 0) {
 		bond_set_carrier(bond);
-
-		/* if the last slave was removed, zero the mac address
-		 * of the master so it will be set by the application
-		 * to the mac address of the first slave
-		 */
-		memset(bond_dev->dev_addr, 0, bond_dev->addr_len);
+		eth_hw_addr_random(bond_dev);
+		bond->dev_addr_from_first = true;
 
 		if (bond_vlan_used(bond)) {
 			pr_warning("%s: Warning: clearing HW address of %s while it still has VLANs.\n",
@@ -2234,11 +2229,8 @@ static int bond_release_all(struct net_device *bond_dev)
 		write_lock_bh(&bond->lock);
 	}
 
-	/* zero the mac address of the master so it will be
-	 * set by the application to the mac address of the
-	 * first slave
-	 */
-	memset(bond_dev->dev_addr, 0, bond_dev->addr_len);
+	eth_hw_addr_random(bond_dev);
+	bond->dev_addr_from_first = true;
 
 	if (bond_vlan_used(bond)) {
 		pr_warning("%s: Warning: clearing HW address of %s while it still has VLANs.\n",
@@ -3708,7 +3700,8 @@ static int bond_do_ioctl(struct net_device *bond_dev, struct ifreq *ifr, int cmd
 			break;
 		case BOND_SETHWADDR_OLD:
 		case SIOCBONDSETHWADDR:
-			res = bond_sethwaddr(bond_dev, slave_dev);
+			bond_set_dev_addr(bond_dev, slave_dev);
+			res = 0;
 			break;
 		case BOND_CHANGE_ACTIVE_OLD:
 		case SIOCBONDCHANGEACTIVE:
@@ -4858,6 +4851,13 @@ static int bond_init(struct net_device *bond_dev)
 
 	bond_debug_register(bond);
 
+	/* Ensure valid dev_addr */
+	if (is_zero_ether_addr(bond_dev->dev_addr) &&
+	    bond_dev->addr_assign_type == NET_ADDR_PERM) {
+		eth_hw_addr_random(bond_dev);
+		bond->dev_addr_from_first = true;
+	}
+
 	__hw_addr_init(&bond->mc_list);
 	return 0;
 }

drivers/net/bonding/bonding.h

@@ -248,6 +248,7 @@ struct bonding {
 	/* debugging support via debugfs */
 	struct	 dentry *debug_dir;
 #endif /* CONFIG_DEBUG_FS */
+	bool	dev_addr_from_first;
 };
 
 static inline bool bond_vlan_used(struct bonding *bond)