linux-next: add utrace tree

[Oleg Nesterov]

On 01/21, Linus Torvalds wrote:
>
> On Thu, 21 Jan 2010, Andrew Morton wrote:
> >
> > ptrace is a nasty, complex part of the kernel which has a long history
> > of problems, but it's all been pretty quiet in there for the the past few
> > years.
>
> More importantly, we're not ever going to get rid of it.

Unfortunately, you are right. The current ptrace (as it is visible from
user-space) should stay forever.

> Quite frankly, judging my all past history we have ever seen in kernel
> interfaces, new an non-portable interfaces simply are never used. The
> whole question whether they are nicer or not is entirely immaterial.

I have to admit this point looks very reasonable to me. Except, can't
resist, ptrace itself is hardly portable.

> I'm personally very dubious that there are any merits to utrace that
> outweigh the very clear disadvantages: just another layer that adds a new
> level of abstraction to the only interface that people actually _use_,
> namely ptrace.

Of course they can't use other interfaces, we don't have them. And
without the new abstraction layer we will never have, I think.

Oleg.