arp: flush arp cache on IFF_NOARP change

IFF_NOARP affects what kind of neighbor entries are created
(nud NOARP or nud INCOMPLETE). If the flag changes, flush the arp
cache to refresh all entries.

Signed-off-by: Timo Teräs <timo.teras@iki.fi>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>

v2->v3: shortened notifier_info struct name
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 0 deletions

diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index bf574029a183..4429b013f269 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -1235,12 +1235,18 @@ static int arp_netdev_event(struct notifier_block *this, unsigned long event,
                             void *ptr)
 {
         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+        struct netdev_notifier_change_info *change_info;
 
         switch (event) {
         case NETDEV_CHANGEADDR:
                 neigh_changeaddr(&arp_tbl, dev);
                 rt_cache_flush(dev_net(dev));
                 break;
+        case NETDEV_CHANGE:
+                change_info = ptr;
+                if (change_info->flags_changed & IFF_NOARP)
+                        neigh_changeaddr(&arp_tbl, dev);
+                break;
         default:
                 break;
         }