Inverted retry condition in SysUtil.link_infos() makes retry loop ineffective

[MahmoudSultan1]

In library/network_connections.py, the retry logic in link_infos() around line 236 has an inverted condition:

except Exception:
    if try_count < 50:
        raise
    continue

This re-raises the exception immediately on the first failure instead of retrying. Hence, continue is never reached.

The fix is to invert the condition:

except Exception:
    if try_count >= 50:
        raise
    continue

Present in 1.17.9 and current main.

[richm]

@MahmoudSultan1 thanks. How are you able to cause this condition to happen?

[MahmoudSultan1]

@MahmoudSultan1 thanks. How are you able to cause this condition to happen?

This is reproduced intermittently on a system with a large number of network interfaces configured. The race window between the two consecutive _link_infos_fetch() calls becomes more likely as the number of interfaces increases, since reading /sys/class/net/ takes longer and there is more opportunity for interface state to change between the two reads.

The logic issue can be verified by looking at any similar pattern where an exception is raised within the retry loop, making it a single attempt loop.

[richm]

Fixed by #874 - @MahmoudSultan1 basically the fix you suggested, and some unit tests to exercise the code.