netdev - Re: arping stuck with ENOBUFS in 4.19.150

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Date:   Fri, 30 Oct 2020 11:50:54 +0000
From:   Joakim Tjernlund <Joakim.Tjernlund@...inera.com>
To:     "dsahern@...il.com" <dsahern@...il.com>,
        "linyunsheng@...wei.com" <linyunsheng@...wei.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "kuba@...nel.org" <kuba@...nel.org>
Subject: Re: arping stuck with ENOBUFS in 4.19.150

On Fri, 2020-10-30 at 09:36 +0800, Yunsheng Lin wrote:
> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.
> 
> 
> On 2020/10/29 23:18, David Ahern wrote:
> > On 10/29/20 8:10 AM, Joakim Tjernlund wrote:
> > > OK, bisecting (was a bit of a bother since we merge upstream releases into our tree, is there a way to just bisect that?)
> > > 
> > > Result was commit "net: sch_generic: aviod concurrent reset and enqueue op for lockless qdisc"  (749cc0b0c7f3dcdfe5842f998c0274e54987384f)
> > > 
> > > Reverting that commit on top of our tree made it work again. How to fix?
> > 
> > Adding the author of that patch (linyunsheng@...wei.com) to take a look.
> > 
> > 
> > > 
> > >  Jocke
> > > 
> > > On Mon, 2020-10-26 at 12:31 -0600, David Ahern wrote:
> > > > 
> > > > On 10/26/20 6:58 AM, Joakim Tjernlund wrote:
> > > > > Ping  (maybe it should read "arping" instead :)
> > > > > 
> > > > >  Jocke
> > > > > 
> > > > > On Thu, 2020-10-22 at 17:19 +0200, Joakim Tjernlund wrote:
> > > > > > strace arping -q -c 1 -b -U  -I eth1 0.0.0.0
> > > > > > ...
> > > > > > sendto(3, "\0\1\10\0\6\4\0\1\0\6\234\v\6 \v\v\v\v\377\377\377\377\377\377\0\0\0\0", 28, 0, {sa_family=AF_PACKET, proto=0x806, if4, pkttype=PACKET_HOST, addr(6)={1, ffffffffffff},
> > > > > > 20) = -1 ENOBUFS (No buffer space available)
> > > > > > ....
> > > > > > and then arping loops.
> > > > > > 
> > > > > > in 4.19.127 it was:
> > > > > > sendto(3, "\0\1\10\0\6\4\0\1\0\6\234\5\271\362\n\322\212E\377\377\377\377\377\377\0\0\0\0", 28, 0, {sa_family=AF_PACKET, proto=0x806, if4, pkttype=PACKET_HOST, addr(6)={1,
> > > > > > ffffffffffff}, 20) = 28
> > > > > > 
> > > > > > Seems like something has changed the IP behaviour between now and then ?
> > > > > > eth1 is UP but not RUNNING and has an IP address.
> 
> "eth1 is UP but not RUNNING" usually mean user has configure the netdev as up,
> but the hardware has not detected a linkup yet.
> 
> Also What is the output of "ethtool eth1"?

echo 1 >  /sys/class/net/eth1/carrier
cu3-jocke ~ # arping -q -c 1 -b -U  -I eth1 0.0.0.0
cu3-jocke ~ # echo 0 >  /sys/class/net/eth1/carrier
cu3-jocke ~ # arping -q -c 1 -b -U  -I eth1 0.0.0.0
^Ccu3-jocke ~ # ethtool eth1
Settings for eth1:
	Supported ports: [ MII ]
	Supported link modes:   1000baseT/Full 
	Supported pause frame use: Symmetric Receive-only
	Supports auto-negotiation: Yes
	Advertised link modes:  1000baseT/Full 
	Advertised pause frame use: Symmetric Receive-only
	Advertised auto-negotiation: Yes
	Speed: 10Mb/s
	Duplex: Half
	Port: MII
	PHYAD: 1
	Transceiver: external
	Auto-negotiation: on
	Current message level: 0x00000037 (55)
			       drv probe link ifdown ifup
	Link detected: no

We have a writeable carrier since eth device is PHY less. Maybe that path is different ?
Check drivers/net/ethernet/freescale/dpaa/dpa_eth.c

> 
> It would be good to see the status of netdev before and after executing arping cmd
> too.

hmm, how do you mean?

> 
> Thanks.
> 
> > > > > > 
> > > > > >  Jocke
> > > > > 
> > > > 
> > > > do a git bisect between the releases to find out which commit is causing
> > > > the change in behavior.
> 
> unfortunately, I did not reproduce the above problem in 4.19.150 too.
> 
> root@(none)$ arping -q -c 1 -b -U  -I eth0 0.0.0.0
> root@(none)$ arping -v
> ARPing 2.21, by Thomas Habets <thomas@...ets.se>
> usage: arping [ -0aAbdDeFpPqrRuUv ] [ -w <sec> ] [ -W <sec> ] [ -S <host/ip> ]
>               [ -T <host/ip ] [ -s <MAC> ] [ -t <MAC> ] [ -c <count> ]
>               [ -C <count> ] [ -i <interface> ] [ -m <type> ] [ -g <group> ]
>               [ -V <vlan> ] [ -Q <priority> ] <host/ip/MAC | -B>
> For complete usage info, use --help or check the manpage.
> root@(none)$ cat /proc/version
> Linux version 4.19.150 (linyunsheng@...ntu) (gcc version 5.4.0 20160609 (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.12)) #4 SMP PREEMPT Fri Oct 30 09:22:06 CST 2020
> 
> 
> 
> > > 
> > 
> >