Errors using span interface on if_bridge(4)

[hiren panchasara]

Below is my setup:
11.0-CURRENT FreeBSD 11.0-CURRENT #1 r260789:260806M: Thu Jan 23
21:18:08 UTC 2014
(n/w stack is untouched)

ix1: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric
0 mtu 1500
        options=8400b8<VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,VLAN_HWTSO>
        ether 38:ea:a7:8b:af:c4
        inet6 fe80::3aea:a7ff:fe8b:afc4%ix1 prefixlen 64 scopeid 0x6
        inet 10.73.149.91 netmask 0xffffff00 broadcast 10.73.149.255
        nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
        media: Ethernet autoselect (10Gbase-Twinax <full-duplex>)
        status: active
ix2: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric
0 mtu 1500
        options=8400b8<VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,VLAN_HWTSO>
        ether 90:e2:ba:30:73:40
        inet6 fe80::92e2:baff:fe30:7340%ix2 prefixlen 64 scopeid 0x7
        inet 192.168.0.2 netmask 0xffffff00 broadcast 192.168.0.255
        nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
        media: Ethernet autoselect (10Gbase-Twinax <full-duplex>)
        status: active
ix3: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric
0 mtu 1500
        options=8400b8<VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,VLAN_HWTSO>
        ether 90:e2:ba:30:73:41
        inet6 fe80::92e2:baff:fe30:7341%ix3 prefixlen 64 scopeid 0x8
        inet 192.168.0.3 netmask 0xffffff00 broadcast 192.168.0.255
        nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
        media: Ethernet autoselect (autoselect <full-duplex>)
        status: active
bridge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        ether 02:a1:25:9a:8f:00
        nd6 options=9<PERFORMNUD,IFDISABLED>
        id 00:00:00:00:00:00 priority 32768 hellotime 2 fwddelay 15
        maxage 20 holdcnt 6 proto rstp maxaddr 2000 timeout 1200
        root id 00:00:00:00:00:00 priority 32768 ifcost 0 port 0
        member: ix1 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
                ifmaxaddr 0 port 6 priority 128 path cost 2000
        member: ix2 flags=8<SPAN>
                ifmaxaddr 0 port 7 priority 128 path cost 2000

ix2 and ix3 are connected back to back via a cable so that I can snoop
any traffic arriving on bridge0 on to ix3.

I have tcpdump going on all 3 interfaces. What I am seeing is
interesting when I send data to ix1 via iperf3 (iperf3 -c
10.73.149.91) . I see packets coming to ix1, getting copied to ix2 but
on ix3 I only see a few packets making it successfully, for rest I
see:

23:30:01.308691 IP bad-hlen 0
23:30:01.308700 IP bad-hlen 0
23:30:01.308711 IP bad-hlen 0

Failure is intermittent. Some packets get through but I see this error
for others.

Looking at the packet carefully, for all those packets with errors,
header length for ipv4 is being reported as 0. Only other indication I
could see was:

-bash-4.2$ sysctl -a | grep checksum_errs
dev.ix.0.mac_stats.checksum_errs: 0
dev.ix.1.mac_stats.checksum_errs: 0
dev.ix.2.mac_stats.checksum_errs: 0
dev.ix.3.mac_stats.checksum_errs: 5686743

I also disabled tso and lro on all of them.

Looking at the code: if_bridge.c has bridge_span() which does
m_copypacket() to span interface.

2549                 mc = m_copypacket(m, M_NOWAIT);
2550                 if (mc == NULL) {
2551                         sc->sc_ifp->if_oerrors++;
2552                         continue;
2553                 }
2554
2555                 bridge_enqueue(sc, dst_if, mc);

Now, I am not sure if its failing at m_copypacket() or after that in
bridge_enqueue(). Not sure how do I look at if_oerrors count.

Any further help in debugging would be great.

cheers,
Hiren