Most of the code handling sessions' MTU has no effect. The ->mtu field in struct l2tp_session might be used at session creation time, but neither PPP nor Ethernet pseudo-wires take updates into account.
L2TP sessions don't have a concept of MTU, which is the reason why ->mtu is mostly ignored. MTU should remain a network device thing. Therefore this patch set does not try to propagate/update ->mtu to/from the device. That would complicate the code unnecessarily. Instead this field and the associated ioctl commands and netlink attributes are removed. Patch #1 defines l2tp_tunnel_dst_mtu() in order to simplify the following patches. Then patches #2 and #3 remove MTU handling from PPP and Ethernet pseudo-wires respectively. Guillaume Nault (3): l2tp: define l2tp_tunnel_dst_mtu() l2tp: simplify MTU handling in l2tp_ppp l2tp: ignore L2TP_ATTR_MTU include/uapi/linux/l2tp.h | 2 +- net/l2tp/l2tp_core.c | 1 - net/l2tp/l2tp_core.h | 20 +++++++++-- net/l2tp/l2tp_debugfs.c | 3 +- net/l2tp/l2tp_eth.c | 25 +++++-------- net/l2tp/l2tp_netlink.c | 9 +---- net/l2tp/l2tp_ppp.c | 74 ++++++++++----------------------------- 7 files changed, 47 insertions(+), 87 deletions(-) -- 2.18.0
