On Thu, 20 Oct 2016 20:08:26 +0000 (UTC), a...@asbjorn.biz wrote: > diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c > index 965f7e3..ba82dcc 100644 > --- a/net/l2tp/l2tp_eth.c > +++ b/net/l2tp/l2tp_eth.c > @@ -259,6 +259,7 @@ static int l2tp_eth_create(struct net *net, u32 > tunnel_id, u32 session_id, u32 p > session->mtu = dev->mtu - session->hdr_len; > dev->mtu = session->mtu; > dev->needed_headroom += session->hdr_len; > + dev->max_mtu = ETH_MAX_MTU - dev->needed_headroom;
I forgot to add that subtracting dev->needed_headroom doesn't give the exact maximum MTU, but one that is a bit too high. It could also just be set to ETH_MAX_MTU, to indicate that the encapsulation is not included. Calculations like in R. Parameswaran's patch is needed for the exact one. https://lkml.org/lkml/2016/10/17/3 -- Best regards Asbjørn Sloth Tønnesen