python-udsoncan: Socket timeout when trying to send data on second socket

Hi,

I’m currently facing a quite systematic issue when using 2 different sockets to send UDS data on the same bus.

The stack trace ends like this:

    IsoTPSocketConnection.send(self, data)
  File "/venv/lib/python3.8/site-packages/udsoncan/connections.py", line 65, in send
    self.specific_send(payload)
  File "/venv/lib/python3.8/site-packages/udsoncan/connections.py", line 321, in specific_send
    self.tpsock.send(payload)
  File "/venv/lib/python3.8/site-packages/isotp/tpsock/__init__.py", line 89, in send
    return self._socket.send(*args, **kwargs)
socket.timeout: timed out

• I’m running Ubuntu 20.04LTS and the issue appeared after kernel update from 5.15.0-78-generic to 5.15.0-79-generic.
• I also reproduced the issue with Ubuntu 22.04 LTS after update from 5.19.0-45-generic to 6.2.0-33-generic.
• Moving back to old kernels restores the good behavior.

In details, the aim of my project is to simulate UDS conversation then:

• opening a socket to simulate UDS requests
• opening a second socket to simulate the answers

The 2 sockets are opened successfully, the first one sends the request, the second one raises an exception when trying to send.

This setup was working well with old kernels but with recent ones, the timeout is very frequent but not systematic.

I tried without success:

• to update all python libs linked to can communication (udsoncan, can-isotp, python-can, msgpack 0.6.2)
• to install most recent kernel, with the hope to get it fixed

Could you help me to identify the component which introduced this “issue”? I’m not familiar with the different layers in action for this topic:

• python libs
• kernel modules
• kernel core

Thanks in advance, best regards,