[lttng-dev] Quick questions about liburcu and RCU in general

[Paul E. McKenney]

On Tue, May 07, 2013 at 04:51:12PM +0200, Richard Braun wrote:
> On Tue, May 07, 2013 at 07:23:52AM -0700, Paul E. McKenney wrote:
> > Yes, LGPLv2+ allows you to migrate to LGPLv3+, which is compatible with
> > GPLv3+.  So as long as you derive the code from lttng's userspace-rcu
> > library, you are set.
> > 
> > That said, you could also just link userspace-rcu into your GPLv3+
> > application.
> 
> My question is rather about the techniques than the existing
> implementations. Is it safe to implement RCU in an unrelated project under
> GPLv3+, considering it's patented ?

I am not a lawyer, but my understanding is that the GPL patent protection
applies to derived works.  So if you start with userspace-rcu, adapt it
to your application, and relicense to GPLv3+, you should be OK.  I do
not believe this works if you do a cleanroom implementation, but again,
I am not a lawyer.

							Thanx, Paul