Re: dumpcap: weird failure with six IPv6 hosts in the filter

[Konstantin Ananyev <konstantin.v.ananyev@yandex.ru>]

17.06.2024 22:40, Stephen Hemminger пишет:
> On Mon, 17 Jun 2024 23:43:19 +0300
> Isaac Boukris <iboukris@gmail.com> wrote:
> 
>> On Mon, Jun 17, 2024 at 10:37 PM Isaac Boukris <iboukris@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