4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Xin Long <[email protected]>

[ Upstream commit ffc2b6ee417435605ee8bb1eb4c8f02e9ff4b4a5 ]

It's safe to remove the setting of dev's needed_headroom and mtu in
__gre_tunnel_init, as discussed in [1], ip_tunnel_newlink can do it
properly.

Now Eric noticed that it could cover the mtu value set in do_setlink
when creating a ip_gre dev. It makes IFLA_MTU param not take effect.

So this patch is to remove them to make IFLA_MTU work, as in other
ipv4 tunnels.

  [1]: https://patchwork.ozlabs.org/patch/823504/

Fixes: c54419321455 ("GRE: Refactor GRE tunneling code.")
Reported-by: Eric Garver <[email protected]>
Signed-off-by: Xin Long <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 net/ipv4/ip_gre.c |    5 -----
 1 file changed, 5 deletions(-)

--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -951,9 +951,6 @@ static void __gre_tunnel_init(struct net
 
        t_hlen = tunnel->hlen + sizeof(struct iphdr);
 
-       dev->needed_headroom    = LL_MAX_HEADER + t_hlen + 4;
-       dev->mtu                = ETH_DATA_LEN - t_hlen - 4;
-
        dev->features           |= GRE_FEATURES;
        dev->hw_features        |= GRE_FEATURES;
 
@@ -1253,8 +1250,6 @@ static int erspan_tunnel_init(struct net
                       sizeof(struct erspanhdr);
        t_hlen = tunnel->hlen + sizeof(struct iphdr);
 
-       dev->needed_headroom = LL_MAX_HEADER + t_hlen + 4;
-       dev->mtu = ETH_DATA_LEN - t_hlen - 4;
        dev->features           |= GRE_FEATURES;
        dev->hw_features        |= GRE_FEATURES;
        dev->priv_flags         |= IFF_LIVE_ADDR_CHANGE;


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