Re: [RFC, PATCH 0/2] utrace/ptrace: simplify/cleanup ptrace attach

[Ingo Molnar <mingo@elte.hu>]

* Oleg Nesterov <oleg@redhat.com> wrote:

> On 05/04, Andrew Morton wrote:
> >
> > On Mon,  4 May 2009 12:43:48 -0700 (PDT)
> > Roland McGrath <roland@redhat.com> wrote:
> >
> > > I guess we should take Andrew's advice on this.  To me, it 
> > > makes most sense just to order the -mm patches so utrace comes 
> > > later, and replace the utrace patch as necessary with a 
> > > compatible version.  Perhaps things would be simpler if we 
> > > made a separate standalone series or git tree (tip/ptrace?) 
> > > for ptrace cleanups.
> >
> > Staging the utrace patch at end-of-series would make sense if 
> > utrace is not on track for a 2.6.31 merge.
> >
> > And afaict, this is indeed the case - things seem to have gone a 
> > bit quiet on the utrace front lately.
> 
> The only goal of current ptrace cleanups is to simplify the 
> "ptrace over utrace" change (hopefully they make sense by 
> themselves though).
> 
> I am obviously biased, but imho the only real problem with 
> utrace-ptrace.patch is the current ptrace code which needs 
> cleanups.

Yes. But realize the fundamental reason for that: _without_ 
ptrace-over-utrace the utrace core code is a big chunk of dead code 
only used on the fringes. I see and agree with all the future uses 
of utrace, but it's easy to be problem-free if a facility is not 
used by anything significant.

So a clean ptrace-over-utrace plugin is absolutely needed for utrace 
to go upstream in v2.6.31. The ftrace plugin alone does not justify 
it. The real prize here is a (much!) cleaner ptrace code. Once 
ptrace is driven via utrace and it works, its value (and trust 
level) will skyrocket.

	Ingo