* MIT-style license :
-xchg() privimitive has been rewritten from scratch starting from atomic_ops 1.2
+xchg() primitive has been rewritten from scratch starting from atomic_ops 1.2
which has a MIT-style license that is intended to allow use in both free and
proprietary software:
http://www.hpl.hp.com/research/linux/atomic_ops/LICENSING.txt