About the memory barrier in BSD libc

[Fengwei yin]

Hi list,
If this is not correct question on the list, please let me know and
sorry for noise.

I have a question regarding the BSD libc for SMP arch. I didn't see
memory barrier used in libc.
How can we make sure it's safe on SMP arch?

BTW, there are memory barrier used in kernel instead. So I suppose the
memory barrier is needed.

Regards
Yin, Fengwei