From: Xin Long <lucien....@gmail.com>
Date: Mon, 25 Dec 2017 14:45:12 +0800
> Commit 582442d6d5bc ("ipv6: Allow the MTU of ipip6 tunnel to be set
> below 1280") fixed a mtu setting issue. It works for ipip6 tunnel.
>
> But ip6gre dev updates the mtu also with ip6_tnl_change_mtu. Since
> the inner packet over ip6gre can be ipv4 and it's mtu should also
> be allowed to set below 1280, the same issue also exists on ip6gre.
>
> This patch is to fix it by simply changing to check if parms.proto
> is IPPROTO_IPV6 in ip6_tnl_change_mtu instead, to make ip6gre to
> go to 'else' branch.
>
> Signed-off-by: Xin Long <lucien....@gmail.com>
Applied.
