Mathieu Desnoyers May 13th, 2009 IBM Corporation allowed LGPLv2.1+ licensing of their contribution to the userspace RCU library in a patch submitted on May 8, 2009 from Paul E. McKenney and reviewed by Steven L. Bennett: https://lists.lttng.org/pipermail/lttng-dev/2009-May/012835.html I (Mathieu Desnoyers) re-implemented ACCESS_ONCE(), likely(), unlikely() and barrier() from scratch without reference to the original code. commit id : 2dc5fa0f7cfbfb0a64a7a67b39626650e863f16a Bert Wesarg approved LGPL relicensing of his patch in an email dated May 13, 2009 : http://lkml.org/lkml/2009/5/13/16 xchg() primitives has been rewritten from a MIT-licensed cmpxchg for Intel and powerpc. They are MIT-licensed and therefore usable in LGPL code. This cmpxchg code was obtained from the atomic_ops project: http://www.hpl.hp.com/research/linux/atomic_ops/ I (Mathieu Desnoyers) wrote the remainder of the code. The license for the library files in this project was therefore changed to LGPLv2.1 on May 13, 2009, as detailed in LICENSE.