ip6_gre: Fix MTU setting for ip6gretap
When creat an ip6gretap interface with an unreachable route,
the MTU is about 14 bytes larger than what was needed.
If the remote address is reachable:
ping6 2001:0:130::1 -c 2
PING 2001:0:130::1(2001:0:130::1) 56 data bytes
64 bytes from 2001:0:130::1: icmp_seq=1 ttl=64 time=1.46 ms
64 bytes from 2001:0:130::1: icmp_seq=2 ttl=64 time=81.1 ms
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index af503f5..a6fe339 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -1027,6 +1027,8 @@
dev->hard_header_len = LL_MAX_HEADER + t_hlen;
dev->mtu = ETH_DATA_LEN - t_hlen;
+ if (dev->type == ARPHRD_ETHER)
+ dev->mtu -= ETH_HLEN;
if (!(tunnel->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
dev->mtu -= 8;