to be inserted,
2) acquire the futex lock,
3) add the lock entry, with its thread id (TID) in the bottom 29 bits
to be inserted,
2) acquire the futex lock,
3) add the lock entry, with its thread id (TID) in the bottom 29 bits
to be removed,
2) remove the lock entry for this lock from the 'head' list,
2) release the futex lock, and
to be removed,
2) remove the lock entry for this lock from the 'head' list,
2) release the futex lock, and