Re: [PATCHv4 bpf-next 0/2] xdp: add dev map multicast support

On Tue, Jun 16, 2020 at 11:09:22AM +0200, Jesper Dangaard Brouer wrote:

quoted

quoted

BTW, when using pktgen, I got an panic because the skb don't have enough
header room. The code path looks like

do_xdp_generic()
  - netif_receive_generic_xdp()
    - skb_headroom(skb) < XDP_PACKET_HEADROOM
      - pskb_expand_head()
        - BUG_ON(skb_shared(skb))

So I added a draft patch for pktgen, not sure if it has any influence.  

Hmm, as Jesper said pktgen was really not intended to be used this way,
so I guess that's why. I guess I'll let him comment on whether he thinks
it's worth fixing; or you could send this as a proper patch and see if
anyone complains about it ;)

Don't use pktgen in this way with veth.  If anything pktgen should
detect that you use pktgen in virtual interfaces and reject/disallow
that you do this.

OK, got it.

Thanks
Hangbin