bridge: trigger RTM_NEWLINK when interface is modified by bridge ioctl

Currently, there is a difference in netlink events received when an
interface is modified through bridge ioctl() or through netlink. This
patch generates additional events when an interface is added to or
removed from a bridge via ioctl().

When adding then removing an interface from a bridge with netlink, we
get:

5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue master bridge0 state UNKNOWN group default
    link/ether 9e:da:60:ee:cf:c8 brd ff:ff:ff:ff:ff:ff
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue master bridge0 state UNKNOWN group default
    link/ether 9e:da:60:ee:cf:c8 brd ff:ff:ff:ff:ff:ff

5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue master bridge0 state UNKNOWN group default
    link/ether 9e:da:60:ee:cf:c8 brd ff:ff:ff:ff:ff:ff
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
Deleted 5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default
    link/ether 9e:da:60:ee:cf:c8 brd ff:ff:ff:ff:ff:ff

When using ioctl():

5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue master bridge0 state UNKNOWN group default
    link/ether 9e:da:60:ee:cf:c8 brd ff:ff:ff:ff:ff:ff
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue master bridge0 state UNKNOWN group default
    link/ether 9e:da:60:ee:cf:c8 brd ff:ff:ff:ff:ff:ff

5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue master bridge0 state UNKNOWN group default
    link/ether 9e:da:60:ee:cf:c8 brd ff:ff:ff:ff:ff:ff
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
Deleted 5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default
    link/ether 9e:da:60:ee:cf:c8 brd ff:ff:ff:ff:ff:ff

Without this patch, the last netlink notification is not sent.
Signed-off-by: Vincent Bernat <vincent@bernat.im>
Reviewed-by: Stephen Hemminger <stephen@networkplumber.org>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_ioctl.c

@@ -102,6 +102,9 @@ static int add_del_if(struct net_bridge *br, int ifindex, int isadd)
 	else
 		ret = br_del_if(br, dev);
 
+	if (!ret)
+		rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_MASTER, GFP_KERNEL);
+
 	return ret;
 }