[infogulch]

What about:

     #define LOCKED(lk) for(int i=lk_lock(lk); i == 0; lk_unlock(lk), i++)

Probably better to test for 0 exactly, in case it fails. You don't want it to unlock twice just because it returns -1.

[eps]

This is so wrong on so many levels.

[infogulch]

It's not any worse than what was suggested in the linked article...