dumpcap: weird failure with six IPv6 hosts in the filter

[Konstantin Ananyev]

Hi Isaac,

> 
> On Wed, Jun 19, 2024 at 2:06 AM Konstantin Ananyev
> <konstantin.v.ananyev at yandex.ru> wrote:
>>
>> 17.06.2024 22:40, Stephen Hemminger пишет:
>>> On Mon, 17 Jun 2024 23:43:19 +0300
>>> Isaac Boukris <iboukris at gmail.com> wrote:
>>>
>>>> On Mon, Jun 17, 2024 at 10:37 PM Isaac Boukris <iboukris at gmail.com> wrote:
>>>>>
>>>>>> Just a quick update that I still see the issue in my env with the
>>>>>> master branch (24.07.0-rc0), I'm now testing by adding the filter to
>>>>>> 'sample_filters' in test_bpf.c and running:
>>>>>> time sudo build/app/dpdk-test bpf_convert_autotest
>>>>>>
>>>>>> With 5 hosts it takes less than 2 secs, with 6 it takes about 25 secs,
>>>>>> i'll try to strace it maybe.
>>>>>
>>>>> strace was useless, no syscalls for ~18 secs, not sure how to debug it
>>>>> further, valgrind / callgrind don't work on dpdk..
>>>>>
>>>>> It doesn't seem to be about the size though, I was able to produce
>>>>> larger bpf code with ipv4 addresses and it worked fine too.
>>>>
>>>> Debugged a bit further with gdb, it looks like it is stuck in a while
>>>> loop in lib/bpf/bpf_validate.c:evaluate(), there is a comment saying
>>>> "make sure we evaluate each node only once" but it seem to go back and
>>>> forth on the same idx's afaict.
>>>
>>> No idea, only original author understands the verifier.
>>> Having our own unique verifier may not be a good idea.
>>> There some other userspace BPF projects, seems like a good place for
>>> convergence.
>>>
>>>
>>> https://lpc.events/event/17/contributions/1639/attachments/1280/2585/userspace-ebpf-bpftime-lpc.pdf
>>
>> hi Isaac,
>> please create a bug report in DPDK bugzilla.
>> Ideally with a clear and simple way to reproduce
>> the bug you are facing in the description.
>> I'll try to have a look when I'll have some free time.
>> Thanks
>> Konstantin
> 
> Done:
> 
> https://bugs.dpdk.org/show_bug.cgi?id=1465


In case you didn't get update from the bugzilla,
here is a patch to try, when you'll get a chance:
http://patchwork.dpdk.org/project/dpdk/list/?series=32321
Thanks
Konstantin


> 
> Thanks a lot!