> I think adding polling to such a widely-used primitive is out of question.

I'm guessing this is because of the perceived performance impact?  (That's the main thought I have against polling in this case.)  Or is it something else?

I can certainly look at tweaking the 3 mutex implementations I mentioned previously, but I do expect that will be a bit more code; I at least wanted to put the "simpler" idea out there.  Fully knowing that "simpler" isn't necessarily better.