RE: iMX6 FEC driver Linux-fslc 4.17 - IPV6 Multicast not working when unplugging/plugging ethernet cable

[Andy Duan]

From: Stefano Cappa <stefano.cappa.ks89@xxxxxxxxx>
> Hi everyone,
> I already posted this in NXP forum as a comment
> (https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fco
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> A user in meta-freescale's mailing list suggested to resend this message to the
> emails obtained running "./scripts/get_maintainer.pl -F
> drivers/net/ethernet/freescale/fec_main.c".
> 
> 
> The problem is:
> 
> If I boot my iMX6 device with ethernet cable attached and I execute "ping6
> ff02::fb" to ping the multicast address I get this response:
> ~# ping6 ff02::fb
> PING ff02::fb (ff02::fb): 56 data bytes
> 64 bytes from fe80::c2f:eff:fe11:2d71: seq=0 ttl=64 time=2.057 ms
> 64 bytes from fe80::809:1bfb:8d4c:ae54: seq=0 ttl=64 time=73.101 ms
> (DUP!)
> 64 bytes from fe80::3e28:6dff:feed:5b97: seq=0 ttl=64 time=150.772 ms
> (DUP!)
> 
> 
> Otherwise, If I unplug and plug again ethernet cable, I cannot ping the
> multicast ipv6 address anymore.
> The result is:
> ~# ping6 ff02::fb
> PING ff02::fb (ff02::fb): 56 data bytes
> ping6: sendto: Network is unreachable
> 
> 
> The original NXP discussion was about older version of Linux, however this
> issue is happening with both Linux 4.9.88 and Linux 4.17.
> Probably also with the latest version, but I didn't try.
> 
I just test it on L4.14 kernel, it works as blow log.
If you unplug and plug the ethernet cable, you should see the log print out:
Unplug:  IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
Plug:    IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready

Please check the link status in your local.

Log:
root@imx8mqevk:~# ping6 ff02::fb
PING ff02::fb (ff02::fb): 56 data bytes
64 bytes from fe80::219:19ff:fe81:9149: seq=0 ttl=64 time=0.208 ms
64 bytes from fe80::be30:5bff:feeb:81f1: seq=0 ttl=64 time=1.586 ms (DUP!)
64 bytes from fe80::baac:6fff:fe37:e4d9: seq=0 ttl=64 time=1.611 ms (DUP!)
64 bytes from fe80::85da:f9d1:6bbc:f86d: seq=0 ttl=64 time=1.633 ms (DUP!)
64 bytes from fe80::38b2:b24:bc4a:1475: seq=0 ttl=64 time=1.653 ms (DUP!)
64 bytes from fe80::204:9fff:fe02:e33d: seq=0 ttl=64 time=1.673 ms (DUP!)
64 bytes from fe80::baac:6fff:fe37:e62f: seq=0 ttl=64 time=1.692 ms (DUP!)
64 bytes from fe80::cf53:3c0e:3d04:87c6: seq=0 ttl=64 time=1.712 ms (DUP!)
64 bytes from fe80::204:9fff:fe02:7786: seq=0 ttl=64 time=1.732 ms (DUP!)
64 bytes from fe80::f781:3862:65df:dadd: seq=0 ttl=64 time=1.752 ms (DUP!)
64 bytes from fe80::f69b:5750:754b:4583: seq=0 ttl=64 time=1.771 ms (DUP!)
64 bytes from fe80::204:9fff:fe02:c5eb: seq=0 ttl=64 time=1.791 ms (DUP!)
64 bytes from fe80::204:9fff:fe02:556a: seq=0 ttl=64 time=1.811 ms (DUP!)
64 bytes from fe80::20e:c6ff:fea6:6880: seq=0 ttl=64 time=1.830 ms (DUP!)
64 bytes from fe80::82dc:2912:4288:c88f: seq=0 ttl=64 time=1.850 ms (DUP!)
64 bytes from fe80::1479:ad62:9b34:1e3e: seq=0 ttl=64 time=1.869 ms (DUP!)
64 bytes from fe80::972f:1cc8:846f:85e2: seq=0 ttl=64 time=1.889 ms (DUP!)
64 bytes from fe80::62ae:d015:196e:5d76: seq=0 ttl=64 time=1.908 ms (DUP!)
64 bytes from fe80::204:9fff:fe03:c37e: seq=0 ttl=64 time=2.439 ms (DUP!)
64 bytes from fe80::204:9fff:fe05:cf0f: seq=0 ttl=64 time=2.462 ms (DUP!)
64 bytes from fe80::204:9fff:fe05:cf11: seq=0 ttl=64 time=3.550 ms (DUP!)
^C
--- ff02::fb ping statistics ---
1 packets transmitted, 1 packets received, 20 duplicates, 0% packet loss
round-trip min/avg/max = 0.208/1.829/3.550 ms
root@imx8mqevk:~# [ 2338.265902] fec 30be0000.ethernet eth0: Link is Down
[ 2338.298193] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready

root@imx8mqevk:~# [ 2344.410482] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[ 2344.418129] fec 30be0000.ethernet eth0: Link is Up - 1Gbps/Full - flow control rx/tx

root@imx8mqevk:~# ping6 ff02::fb
PING ff02::fb (ff02::fb): 56 data bytes
64 bytes from fe80::219:19ff:fe81:9149: seq=0 ttl=64 time=0.158 ms
64 bytes from fe80::be30:5bff:feeb:81f1: seq=0 ttl=64 time=1.853 ms (DUP!)
64 bytes from fe80::38b2:b24:bc4a:1475: seq=0 ttl=64 time=1.879 ms (DUP!)
64 bytes from fe80::85da:f9d1:6bbc:f86d: seq=0 ttl=64 time=1.901 ms (DUP!)
64 bytes from fe80::cf53:3c0e:3d04:87c6: seq=0 ttl=64 time=1.921 ms (DUP!)
64 bytes from fe80::baac:6fff:fe37:e4d9: seq=0 ttl=64 time=1.940 ms (DUP!)
64 bytes from fe80::f781:3862:65df:dadd: seq=0 ttl=64 time=1.961 ms (DUP!)


> 
> Do you have any suggestions? Is this a bug? This is really a frustrating and I'm
> really surprised to see the same problem also on Linux 4.17.
> 
> 
> PS: I'm sorry for the double email, but the previous one was in html and it was
> rejected.
> 
> Thank u.