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From:   Ian Kumlien <ian.kumlien@gmail.com>
Date:   Wed, 9 Jan 2019 00:00:03 +0100
Message-ID: <CAA85sZt=mrqprwkKLGbv2UMy6vQb0XSc58YrWvqxzK4yhdbpGQ@mail.gmail.com>
Subject: Re: [BUG] v4.20 - bridge not getting DHCP responses? (works in 4.19.13)
To:     Stephen Hemminger <stephen@networkplumber.org>
Cc:     Linux Kernel Network Developers <netdev@vger.kernel.org>,
        jeffrey.t.kirsher@intel.com,
        Roopa Prabhu <roopa@cumulusnetworks.com>,
        nikolay@cumulusnetworks.com,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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On Tue, Jan 8, 2019 at 11:51 PM Stephen Hemminger
<stephen@networkplumber.org> wrote:
> On Tue, 8 Jan 2019 23:10:04 +0100
> Ian Kumlien <ian.kumlien@gmail.com> wrote:
> > On Sun, Jan 6, 2019 at 11:21 PM Ian Kumlien <ian.kumlien@gmail.com> wrote:
> > >
> > > [Sorry for the repost, screwed up the netdev address...]
> > >
> > > Hi,
> > >
> > > Switching from 4.19.x -> 4.20 resulted in DHCP not working for my VM:s.
> > >
> > > My firewall (which also runs the dhcpd) runs VM:s and it does this by
> > > having physical
> > > interfaces attached to bridges - which the VM:s in turn attach to.
> > >
> > > Since 4.20 the VM:s can't use DHCP, it's odd since the requests are
> > > seen - a response is sent but
> > > it never enters the interface attached to the bridge.
> > >
> > > Basically:
> > > VM vnet2: -> br0 -> eno2 -> switch -> eno1 (dhcpd)
> > > dhcpd eno1 -> siwtch and... gone.
> > >
> > > Any clues?
> > >
> > > All the nics are handled by ixgbe
> >
> > So, doing similar tests at work with other drivers works - could it be
> > related to the mac address filter that was added?
> > I don't *really* use VF:s though... (can't really find anything else atm)
> >
> > Will try to test, but the VM:s on this machine is in use.
>
> The default MAC address of the bridge device is the first device assigned
> to the bridge.  Remember most VF interfaces will only allow single MAC address
> and no promiscious mode.

Yeah, I'm not running any VF:s and it just seems like the responses
are dropped somewhere

when looking at "git log v4.19...v4.20
drivers/net/ethernet/intel/ixgbe/" nothing else really stands out...
The machine is also running NAT for my home network and all of that
works just fine...

I started with tcpdump, prooving that packets reached all the way
outside but replies never made it, reboorting
with 4.19.13 resulted in replies appearing in the tcpdump.

I don't quite know where to look - and what can i do to test - i tried
disabling all offloading (due to the UDP
offloading changes) but nothing helped...

Ideas? Patches? ;)