macvlan: return correct error value

A MAC address must be unique among all the macvlan devices with the same
lower device. The only exception is the passthru [sic] mode,
which shares the lower device address.

When duplicate addresses are detected, EBUSY is returned when bringing
the interface up:

    # ip link add macvlan0 link eth0 type macvlan
    # read addr </sys/class/net/eth0/address
    # ip link set macvlan0 address $addr
    # ip link set macvlan0 up
    RTNETLINK answers: Device or resource busy

Use correct error code which is EADDRINUSE, and do the check also
earlier, on address change:

    # ip link set macvlan0 address $addr
    RTNETLINK answers: Address already in use
Signed-off-by: NMatteo Croce <mcroce@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/macvlan.c

@@ -608,7 +608,7 @@ static int macvlan_open(struct net_device *dev)
 		goto hash_add;
 	}
 
-	err = -EBUSY;
+	err = -EADDRINUSE;
 	if (macvlan_addr_busy(vlan->port, dev->dev_addr))
 		goto out;
 
@@ -706,7 +706,7 @@ static int macvlan_sync_address(struct net_device *dev, unsigned char *addr)
 	} else {
 		/* Rehash and update the device filters */
 		if (macvlan_addr_busy(vlan->port, addr))
-			return -EBUSY;
+			return -EADDRINUSE;
 
 		if (!macvlan_passthru(port)) {
 			err = dev_uc_add(lowerdev, addr);
@@ -747,6 +747,9 @@ static int macvlan_set_mac_address(struct net_device *dev, void *p)
 		return dev_set_mac_address(vlan->lowerdev, addr);
 	}
 
+	if (macvlan_addr_busy(vlan->port, addr->sa_data))
+		return -EADDRINUSE;
+
 	return macvlan_sync_address(dev, addr->sa_data);
 }