rtnetlink: support specifying device flags on device creation

rtnetlink: support specifying device flags on device creation

commit e8469ed959c373c2ff9e6f488aa5a14971aebe1f
Author: Patrick McHardy <kaber@trash.net>
Date:   Tue Feb 23 20:41:30 2010 +0100

Support specifying the initial device flags when creating a device though
rtnl_link. Devices allocated by rtnl_create_link() are marked as INITIALIZING
in order to surpress netlink registration notifications. To complete setup,
rtnl_configure_link() must be called, which performs the device flag changes
and invokes the deferred notifiers if everything went well.

Two examples:

# add macvlan to eth0
#
$ ip link add link eth0 up allmulticast on type macvlan

[LINK]11: macvlan0@eth0: <BROADCAST,MULTICAST,ALLMULTI,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN
    link/ether 26:f8:84:02:f9:2a brd ff:ff:ff:ff:ff:ff
[ROUTE]ff00::/8 dev macvlan0  table local  metric 256  mtu 1500 advmss 1440 hoplimit 0
[ROUTE]fe80::/64 dev macvlan0  proto kernel  metric 256  mtu 1500 advmss 1440 hoplimit 0
[LINK]11: macvlan0@eth0: <BROADCAST,MULTICAST,ALLMULTI,UP,LOWER_UP> mtu 1500
    link/ether 26:f8:84:02:f9:2a
[ADDR]11: macvlan0    inet6 fe80::24f8:84ff:fe02:f92a/64 scope link
       valid_lft forever preferred_lft forever
[ROUTE]local fe80::24f8:84ff:fe02:f92a via :: dev lo  table local  proto none  metric 0  mtu 16436 advmss 16376 hoplimit 0
[ROUTE]default via fe80::215:e9ff:fef0:10f8 dev macvlan0  proto kernel  metric 1024  mtu 1500 advmss 1440 hoplimit 0
[NEIGH]fe80::215:e9ff:fef0:10f8 dev macvlan0 lladdr 00:15:e9:f0:10:f8 router STALE
[ROUTE]2001:6f8:974::/64 dev macvlan0  proto kernel  metric 256  expires 0sec mtu 1500 advmss 1440 hoplimit 0
[PREFIX]prefix 2001:6f8:974::/64 dev macvlan0 onlink autoconf valid 14400 preferred 131084
[ADDR]11: macvlan0    inet6 2001:6f8:974:0:24f8:84ff:fe02:f92a/64 scope global dynamic
       valid_lft 86399sec preferred_lft 14399sec

# add VLAN to eth1, eth1 is down
#
$ ip link add link eth1 up type vlan id 1000
RTNETLINK answers: Network is down

<no events>

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>