ip_gre: ipgre_tap device should keep dst

lxin · davem330 · commit d51711c0557d · 2017-10-01T03:46:42.000+01:00
Without keeping dst, the tunnel will not update any mtu/pmtu info,
since it does not have a dst on the skb.

Reproducer:
  client(ipgre_tap1 - eth1) &lt;-----&gt; (eth1 - ipgre_tap1)server

After reducing eth1's mtu on client, then perforamnce became 0.

This patch is to netif_keep_dst in gre_tap_init, as ipgre does.

Reported-by: Jianlin Shi &lt;jishi@redhat.com&gt;
Signed-off-by: Xin Long &lt;lucien.xin@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
@@ -1223,6 +1223,7 @@ static int gre_tap_init(struct net_device *dev)
 {
 	__gre_tunnel_init(dev);
 	dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
+	netif_keep_dst(dev);
 
 	return ip_tunnel_init(dev);
 }

Original file line number	Diff line number	Diff line change
`@@ -1223,6 +1223,7 @@ static int gre_tap_init(struct net_device *dev)`
`1223`	`1223`	`{`
`1224`	`1224`	`__gre_tunnel_init(dev);`
`1225`	`1225`	`dev->priv_flags \|= IFF_LIVE_ADDR_CHANGE;`
	`1226`	`+ netif_keep_dst(dev);`
`1226`	`1227`
`1227`	`1228`	`return ip_tunnel_init(dev);`
`1228`	`1229`	`}`