rtnl: Add support for netdev event to link messages

When netdev events happen, a rtnetlink_event() handler will send
messages for every event in it's white list.  These messages contain
current information about a particular device, but they do not include
the iformation about which event just happened.  So, it is impossible
to tell what just happend for these events.

This patch adds a new extension to RTM_NEWLINK message called IFLA_EVENT
that would have an encoding of event that triggered this
message.  This would allow the the message consumer to easily determine
if it needs to perform certain actions.

Signed-off-by: Vladislav Yasevich <vyasevic@redhat.com>
Acked-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/if_link.h

@@ -157,6 +157,7 @@ enum {
 	IFLA_GSO_MAX_SIZE,
 	IFLA_PAD,
 	IFLA_XDP,
+	IFLA_EVENT,
 	__IFLA_MAX
 };
 
@@ -911,4 +912,14 @@ enum {
 
 #define IFLA_XDP_MAX (__IFLA_XDP_MAX - 1)
 
+enum {
+	IFLA_EVENT_NONE,
+	IFLA_EVENT_REBOOT,		/* internal reset / reboot */
+	IFLA_EVENT_FEATURES,		/* change in offload features */
+	IFLA_EVENT_BONDING_FAILOVER,	/* change in active slave */
+	IFLA_EVENT_NOTIFY_PEERS,	/* re-sent grat. arp/ndisc */
+	IFLA_EVENT_IGMP_RESEND,		/* re-sent IGMP JOIN */
+	IFLA_EVENT_BONDING_OPTIONS,	/* change in bonding options */
+};
+
 #endif /* _UAPI_LINUX_IF_LINK_H */