resource/udev: fix intermittent AttributeError in USBSDWireDevice

[ohporter]

The control_serial attribute is conditionally declared by assignment which causes a race where it may not be declared before being accessed in USBSDWireExport _get_params(). This causes an AttributeError when starting the exporter.

Remove the unused control_path attribute and explicitly declare control_serial to fix it.

Failure log:

Oct 08 12:25:14 sage labgrid-exporter[2757866]: add resource rpi3/USBSDWireDevice: USBSDWireDevice/OrderedDict([('match', OrderedDict([('@ID_SERIAL_SHORT', '202110140001')]))])
Oct 08 12:25:14 sage labgrid-exporter[2757866]: Traceback (most recent call last):
Oct 08 12:25:14 sage labgrid-exporter[2757866]:   File "/opt/labgrid-venv/bin/labgrid-exporter", line 7, in <module>
Oct 08 12:25:14 sage labgrid-exporter[2757866]:     sys.exit(main())
Oct 08 12:25:14 sage labgrid-exporter[2757866]:              ^^^^^^
Oct 08 12:25:14 sage labgrid-exporter[2757866]:   File "/opt/labgrid-venv/lib/python3.11/site-packages/labgrid/remote/exporter.py", line 1109, in main
Oct 08 12:25:14 sage labgrid-exporter[2757866]:     asyncio.run(amain(config), debug=bool(args.debug))
Oct 08 12:25:14 sage labgrid-exporter[2757866]:   File "/usr/lib/python3.11/asyncio/runners.py", line 190, in run
Oct 08 12:25:14 sage labgrid-exporter[2757866]:     return runner.run(main)
Oct 08 12:25:14 sage labgrid-exporter[2757866]:            ^^^^^^^^^^^^^^^^
Oct 08 12:25:14 sage labgrid-exporter[2757866]:   File "/usr/lib/python3.11/asyncio/runners.py", line 118, in run
Oct 08 12:25:14 sage labgrid-exporter[2757866]:     return self._loop.run_until_complete(task)
Oct 08 12:25:14 sage labgrid-exporter[2757866]:            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Oct 08 12:25:14 sage labgrid-exporter[2757866]:   File "/usr/lib/python3.11/asyncio/base_events.py", line 653, in run_until_complete
Oct 08 12:25:14 sage labgrid-exporter[2757866]:     return future.result()
Oct 08 12:25:14 sage labgrid-exporter[2757866]:            ^^^^^^^^^^^^^^^
Oct 08 12:25:14 sage labgrid-exporter[2757866]:   File "/opt/labgrid-venv/lib/python3.11/site-packages/labgrid/remote/exporter.py", line 1032, in amain
Oct 08 12:25:14 sage labgrid-exporter[2757866]:     await exporter.run()
Oct 08 12:25:14 sage labgrid-exporter[2757866]:   File "/opt/labgrid-venv/lib/python3.11/site-packages/labgrid/remote/exporter.py", line 844, in run
Oct 08 12:25:14 sage labgrid-exporter[2757866]:     await self.add_resource(group_name, resource_name, cls, params)
Oct 08 12:25:14 sage labgrid-exporter[2757866]:   File "/opt/labgrid-venv/lib/python3.11/site-packages/labgrid/remote/exporter.py", line 1006, in add_resource
Oct 08 12:25:14 sage labgrid-exporter[2757866]:     res.poll()
Oct 08 12:25:14 sage labgrid-exporter[2757866]:   File "/opt/labgrid-venv/lib/python3.11/site-packages/labgrid/remote/exporter.py", line 161, in poll
Oct 08 12:25:14 sage labgrid-exporter[2757866]:     params = self._get_params()
Oct 08 12:25:14 sage labgrid-exporter[2757866]:              ^^^^^^^^^^^^^^^^^^
Oct 08 12:25:14 sage labgrid-exporter[2757866]:   File "/opt/labgrid-venv/lib/python3.11/site-packages/labgrid/remote/exporter.py", line 424, in _get_params
Oct 08 12:25:14 sage labgrid-exporter[2757866]:     "control_serial": self.local.control_serial,
Oct 08 12:25:14 sage labgrid-exporter[2757866]:                       ^^^^^^^^^^^^^^^^^^^^^^^^^
Oct 08 12:25:14 sage labgrid-exporter[2757866]: AttributeError: 'USBSDWireDevice' object has no attribute 'control_serial'

[Emantor]

@JPEWdev can you test/ack this? I don't have a device to test with.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 45.4%. Comparing base (fc8901c) to head (11c5b75).
⚠️ Report is 4 commits behind head on master.

Additional details and impacted files

@@          Coverage Diff           @@
##           master   #1754   +/-   ##
======================================
  Coverage    45.4%   45.4%           
======================================
  Files         172     172           
  Lines       13503   13503           
======================================
  Hits         6131    6131           
  Misses       7372    7372           

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3.10	45.4% <100.0%> (ø)
3.11	45.4% <100.0%> (ø)
3.12	45.4% <100.0%> (ø)
3.13	45.3% <100.0%> (ø)
3.9	45.4% <100.0%> (ø)

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[JPEWdev]

defaulting control_serial to None makes sense, but not by making it an attribute in this way. IIUC this is for properties you can set in the YAML file, which is not the case for this because whatever you set will be ignored (or rather, overwritten in poll()). I think the better option is to set self.control_serial = None in __attrs_post_init__

[ohporter]

Makes sense to me, thanks. I've updated as suggested.