qdisc errors on Azure VM (TAP Config)

[Stephen Hemminger]

On Thu, 6 Oct 2022 06:08:59 +0000
Dattu Gundu <dattu.gundu at oracle.com> wrote:

> Hi, 
> 
> I am observing the below errors during the bootup of Azure VM.
> 
> I understand these errors started popping from DPDK 20.11.1 due to extended ack support was added in Linux version 4.17
> And used for diagnosing the TAP config in kernel. 
> 
> Is it because we are trying to delete the qdisc before they are created ?
> And looks like the failure is per queue. 
> 
> Am I missing any packages ?
> 
> How to avoid these errors ?
> If they are not serious, is there a way to suppress them ?
> 
> net_vdev_netvsc: probably using routed NetVSC interface "s0p0" (index 7)
> tap_nl_dump_ext_ack(): Cannot delete qdisc with handle of zero
> tap_nl_dump_ext_ack(): Failed to find qdisc with specified classid
> tap_nl_dump_ext_ack(): Failed to find qdisc with specified classid
> tap_nl_dump_ext_ack(): Failed to find qdisc with specified classid
> tap_nl_dump_ext_ack(): Failed to find qdisc with specified classid
> tap_nl_dump_ext_ack(): Failed to find qdisc with specified classid
> tap_nl_dump_ext_ack(): Failed to find qdisc with specified classid
> tap_nl_dump_ext_ack(): Failed to find qdisc with specified classid
> tap_nl_dump_ext_ack(): Failed to find qdisc with specified classid
> net_vdev_netvsc: probably using routed NetVSC interface "s1p0" (index 8)
> tap_nl_dump_ext_ack(): Cannot delete qdisc with handle of zero
> tap_nl_dump_ext_ack(): Failed to find qdisc with specified classid
> tap_nl_dump_ext_ack(): Failed to find qdisc with specified classid
> tap_nl_dump_ext_ack(): Failed to find qdisc with specified classid
> tap_nl_dump_ext_ack(): Failed to find qdisc with specified classid
> tap_nl_dump_ext_ack(): Failed to find qdisc with specified classid
> tap_nl_dump_ext_ack(): Failed to find qdisc with specified classid
> tap_nl_dump_ext_ack(): Failed to find qdisc with specified classid
> tap_nl_dump_ext_ack(): Failed to find qdisc with specified classid
> 
> Currently using below kernel: 
> 5.4.17
> x86_64
> GNU/Linux
> #3 SMP PREEMPT Thu Aug 18 05:23:39 UTC 2022
> 
> Thanks,
> Raghava Dattu.

If possible use netvsc PMD and not the older vdev_netvsc/failsafe/tap stuff.

Are you sure your kernel has all the necessary qdisc to run the failsafe/tap
device. It needs to have flower, mirred, mqprio, etc.