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 <e...@erig.me> Signed-off-by: Xin Long <lucien....@gmail.com> --- net/ipv4/ip_gre.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index 45d97e9..0901de4 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -970,9 +970,6 @@ static void __gre_tunnel_init(struct net_device *dev) 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; @@ -1290,8 +1287,6 @@ static int erspan_tunnel_init(struct net_device *dev) erspan_hdr_len(tunnel->erspan_ver); 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; -- 2.1.0
