> -----Original Message----- > From: Sabrina Dubroca [mailto:s...@queasysnail.net] > Sent: 2017年9月22日 20:23 > To: Eric Dumazet <eric.duma...@gmail.com> > Cc: Jarod Wilson <ja...@redhat.com>; Zhang Shengju > <zhangshen...@cmss.chinamobile.com>; da...@davemloft.net; > will...@google.com; step...@networkplumber.org; > netdev@vger.kernel.org > Subject: Re: [net-next 1/2] dummy: add device MTU validation check > > 2017-09-22, 04:05:09 -0700, Eric Dumazet wrote: > > On Fri, 2017-09-22 at 10:56 +0200, Sabrina Dubroca wrote: > > > 2017-09-21, 08:02:18 -0700, Eric Dumazet wrote: > > > > On Thu, 2017-09-21 at 21:32 +0800, Zhang Shengju wrote: > > > > > Currently, any mtu value can be assigned when adding a new dummy > device: > > > > > [~]# ip link add name dummy1 mtu 100000 type dummy [~]# ip link > > > > > show dummy1 > > > > > 15: dummy1: <BROADCAST,NOARP> mtu 100000 qdisc noop state > DOWN mode DEFAULT group default qlen 1000 > > > > > link/ether 0a:61:6b:16:14:ce brd ff:ff:ff:ff:ff:ff > > > > > > > > > > This patch adds device MTU validation check. > > > > > > > > What is wrong with big MTU on dummy ? > > > > > > It looks like the "centralize MTU checking" series broke that, but > > > only for changing the MTU on an existing dummy device. Commit > > > a52ad514fdf3 defined min_mtu/max_mtu in ether_setup, which dummy > > > uses, but there was no MTU check in dummy prior to that commit. > > > > > > > It looks like we accept big mtu on loopback, right ? > > Yes. I only meant that before commit a52ad514fdf3, there was no range check > on dummy's MTU. Commit 25e3e84b183a ("dummy: expend mtu range for > dummy device") and 8b1efc0f83f1 ("net: remove MTU limits on a few > ether_setup callers") fixed that only partially. It's the same with ifb, btw, > it > didn't have any check before a52ad514fdf3, so we should set min_mtu = > max_mtu = 0. > > -- > Sabrina
I agree, dummy and ifb device should not have any limit on mtu, just like loopback device. I will send v2 patch, and set min/max_mtu to zero for dummy and ifb device, thanks. ZSJ
