Re: [PATCH net-next v7] selftests: net: add tests for PPP

[Paolo Abeni <pabeni@redhat.com>]

On 4/2/26 4:26 AM, Qingfang Deng wrote:
> On Thu, Apr 2, 2026 at 8:56 AM Jakub Kicinski <kuba@kernel.org> wrote:
>> On Wed, 1 Apr 2026 23:45:38 +0800 Qingfang Deng wrote:
>>>> # iperf3: error - unable to connect to server - server may have stopped running or use a different port, firewall issue, etc.: Network is unreachable
>>>> # TEST: PPPoE                                                         [FAIL]
>>>> not ok 1 selftests: net/ppp: pppoe.sh # exit=1
>>>
>>> It looks like pppoe-server fails to start. You may check the syslog to
>>> see what's going on.
>>
>> Hm, we don't capture syslog automatically :S We capture stdout and
>> stderr
>>
>> I'm not even sure there's something listening on syslog in virtme-ng
>> Is it possible to make the daemon log to stdout or a file and dump
>> that file to stdout on failure? Even if we fix the current issue
>> it will be quite inconvenient if we have to go into syslog every time
>> the test is failing. The test output should provide enough info to
>> debug failures.
> 
> Add Cc: Dianne
> 
> I checked the man page of pppoe-server and did not find such option.
> We can instead start our own listener and redirect the syslog to a
> file or stdout:
> 
> socat -u UNIX-RECV:/dev/log,ignoreeof STDOUT &

Note that similar failures in the past in other test-cases were usually
due to timing issues. i.e. the pppoe-server starts in background too
late for the client.

Possibly a somewhat clean solution is to wait in a loop for the
'pppoe-server ready' event, somewhat similar to wait_local_port_listen().

Otherwise an hackish sleep in between should do.

Note that you should be possibly able to reproduce this kind of failure
in a virtualized/slow enough environment (i.e. using vng as described on
nipa wiki)

Finally, note that in this test script you should start the socat
listener only if /dev/log does not exists, or ignore socat startup
errors - because self-test should run also on different systems.

/P