Inconsistent use of the poed system lock

[rothcar]

Poed maintains a system-wide exclusive lock for access to the PoE chipset communications channel. This lock is maintained poorly and the error recovery for failed lock attempts is incorrect. This can lead invalid poed state.

1. the try/except code that manages the exclusive lock includes the safe code path inside the lock exception handler. Meaning, the safe code path can throw an exception similar to the lock syscall and poed cannot tell the difference.
2. Exception handling for a failed lock attempt does not provide adequate context to the user as to the failure cause or location
3. Failed lock attempts are ignored (the safe code path result skipped).

[leonchiang]

1. Change Lock flow to prevent mixing of lock/function exceptions.
2. Will show the calling function name.
3. Will retry 5 times every 0.1s, then execute function (lock acquired) or abort(lock failed).

[leonchiang]

Please check devel-0001 branch tag:
https://github.com/leonchiang/poed/releases/tag/issue_fix_0001