1 files changed, 7 insertions, 2 deletions

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index fb595e8dc15b..59c121b932ac 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -503,8 +503,8 @@ static netdev_tx_t __gre6_xmit(struct sk_buff *skb,
                                __u32 *pmtu, __be16 proto)
 {
         struct ip6_tnl *tunnel = netdev_priv(dev);
-        __be16 protocol = (dev->type == ARPHRD_ETHER) ?
-                          htons(ETH_P_TEB) : proto;
+        struct dst_entry *dst = skb_dst(skb);
+        __be16 protocol;
 
         if (dev->type == ARPHRD_ETHER)
                 IPCB(skb)->flags = 0;
@@ -518,9 +518,14 @@ static netdev_tx_t __gre6_xmit(struct sk_buff *skb,
                 tunnel->o_seqno++;
 
         /* Push GRE header. */
+        protocol = (dev->type == ARPHRD_ETHER) ? htons(ETH_P_TEB) : proto;
         gre_build_header(skb, tunnel->tun_hlen, tunnel->parms.o_flags,
                          protocol, tunnel->parms.o_key, htonl(tunnel->o_seqno));
 
+        /* TooBig packet may have updated dst->dev's mtu */
+        if (dst && dst_mtu(dst) > dst->dev->mtu)
+                dst->ops->update_pmtu(dst, NULL, skb, dst->dev->mtu);
+
         return ip6_tnl_xmit(skb, dev, dsfield, fl6, encap_limit, pmtu,
                             NEXTHDR_GRE);
 }