Re: Re: [PATCH bpf-next] netkit: Add some ethtool ops to provide information to user

[Feng Zhou]

在 2023/12/6 18:57, Daniel Borkmann 写道:
> On 12/6/23 7:59 AM, Feng Zhou wrote:
> > 在 2023/12/4 23:22, Daniel Borkmann 写道:
> > > Thanks, so the netkit_get_link_ksettings is optional. 
> >
> > Yes, netkit_get_link_ksettings really not necessary, I just added it 
> > in line with veth.
> >
> > I don't quite
> > > follow what you
> > > mean with regards to your business logic in veth to obtain peer 
> > > ifindex. What does
> > > the script do exactly with the peer ifindex (aka /why/ is it needed), 
> > > could you
> > > elaborate some more - it's still somewhat too vague? 🙂 E.g. why it 
> > > does not suffice
> > > to look at the device type or other kind of attributes?
> >
> > The scripting logic of the business colleagues should just be simple 
> > logging records, using ethtool. Then they saw that netkit has this 
> > missing, so raised this requirement, so I sent this patch, wanting to 
> > hear your opinions. If you don't think it's necessary, let the 
> > business colleagues modify it.
>
> So it is basically only logging the peer_ifindex data from ethtool but 
> nothing
> more is done with it? Meaning, this was raised as a requirement because 
> this was
> missing from the logging data, or was there anything more to it?
>
> The peer ifindex is already available via IFLA_LINK (which does 
> dev_get_iflink()
> internally to fetch the peer's ifindex). This is also what you see in 
> iproute2:
>
> # ip l
> [...]
> 163: nk0@nk1: <BROADCAST,MULTICAST,NOARP,M-DOWN> mtu 1500 qdisc noop 
> state DOWN group default qlen 1000
>      link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
> 164: nk1@nk0: <BROADCAST,MULTICAST,NOARP,M-DOWN> mtu 1500 qdisc noop 
> state DOWN group default qlen 1000
>      link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
> [...]
> # ip netns add blue
> # ip link set nk1 netns blue
> # ip l
> [...]
> 163: nk0@if164: <BROADCAST,MULTICAST,NOARP> mtu 1500 qdisc noop state 
> DOWN group default qlen 1000
>      link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff link-netns blue
> [...]
>
> The `if164` denotes the peer's ifindex and `link-netns blue` provides 
> info on the netns of the peer.
> This is much better and more generic than the ethtool hack. I would 
> suggest changing the logic to
> rather look at data populated by rtnl_fill_link_netnsid() instead.
>
> Thanks,
> Daniel

Yes, if veth supports ethtool -S to get the function of peer's ifindex, 
it is not necessary for netkit and can be replaced by other ways.