net: introduce new priv_flag indicating iface capable of change mac when running

Introduce IFF_LIVE_ADDR_CHANGE priv_flag and use it to disable
netif_running() check in eth_mac_addr()

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

include/linux/if.h

@@ -81,6 +81,8 @@
 #define IFF_UNICAST_FLT	0x20000		/* Supports unicast filtering	*/
 #define IFF_TEAM_PORT	0x40000		/* device used as team port */
 #define IFF_SUPP_NOFCS	0x80000		/* device supports sending custom FCS */
+#define IFF_LIVE_ADDR_CHANGE 0x100000	/* device supports hardware address
+					 * change when it's running */
 
 
 #define IF_GET_IFACE	0x0001		/* for querying only */

net/ethernet/eth.c

@@ -283,7 +283,7 @@ int eth_mac_addr(struct net_device *dev, void *p)
 {
 	struct sockaddr *addr = p;
 
-	if (netif_running(dev))
+	if (!(dev->priv_flags & IFF_LIVE_ADDR_CHANGE) && netif_running(dev))
 		return -EBUSY;
 	if (!is_valid_ether_addr(addr->sa_data))
 		return -EADDRNOTAVAIL;