TSX lock elision for glibc v12

[Rich Felker]

On Fri, Jun 21, 2013 at 07:27:01PM +0200, Andi Kleen wrote:
> > I don't want to change or expose anything externally if I don't have to.
> > This will make it easier for us to just enable elision without risking
> > to have to maintain other interfaces, break ABIs, etc.
> 
> I don't see the point of checking a new number on all the fast paths
> when it doesn't do anything different.
> 
> With elision it's just the same as TIMED_NP | NO_ELISION 
> 
> So why not use that internally?

I agree. For now, pthread_mutexattr_settype can just set the "no
elision" flag whenever it's called. I don't see a need for a new mutex
type unless it would enable doing something that's actually useful.

Rich