vlan: Don't propagate flag changes on down interfaces.

vlan: Don't propagate flag changes on down interfaces.

commit deede2fabe24e00bd7e246eb81cd5767dc6fcfc7 upstream.

When (de)configuring a vlan interface, the IFF_ALLMULTI ans IFF_PROMISC
flags are cleared or set on the underlying interface. So, if these flags
are changed on a vlan interface that is not up, the flags underlying
interface might be set or cleared twice.

Only propagating flag changes when a device is up makes sure this does
not happen. It also makes sure that an underlying device is not set to
promiscuous or allmulti mode for a vlan device that is down.

Signed-off-by: Matthijs Kooijman <matthijs@stdin.nl>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: This is a dependency of commit d2615bf45069 ("net: core: Always
 propagate flag changes to interfaces"), already backported in 2.6.32.62]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Willy Tarreau <w@1wt.eu>