linux-next: add utrace tree

[Linus Torvalds]

On Fri, 29 Jan 2010, Benjamin Herrenschmidt wrote:
> 
> like returning a fd to poll() on ? :-)

Well, there's the possibility of async polling (rather than the 
synchronous wait that ptrace forces now), but there are other advantages 
to having a "connection" model - like not having to look up the child 
process every time like ptrace does now.

Although 'find_task_by_vpid()' is probably cheap enough that nobody really 
cares. We do a fair job at those hash tables.

			Linus