Re: [RFC][PATCH 0/20] Multiple instances of the process id namespace

[Hubertus Franke <frankeh@watson.ibm.com>]

Eric W. Biederman wrote:
> Hubertus Franke <frankeh@watson.ibm.com> writes:
>
>
> > find_task_by_pid( pid ) { return find_task_pidspace_by_pid ( current->pspace,
> > pid ); }
> >
> > and then only deal with the exceptional cases using find_task_pidspace_by_pid
> > when the pidspace is different..
>
>
> That is a possibility.  However I want to break some eggs so that the
> users are updated appropriately.  It is only by a strenuous act of
> will that I don't change the type of pid,tgid,pgrp,session.
>
> The size of the changes is much less important than being clear.
> So for I want find_task_by_pid to be an absolute interface.

Fair enough, valid answers .. I checked the patch and it would only take
19/33 instances out .. so not the end of the world.

> > >  Does the use of clone to create a new namespace instance look
> > >  like the sane approach?
> >
> > At he surface it looks OK .. how does this work in a multi-threaded
> > process which does cloen ( CLONE_NPSPACE ) ?
> > We discussed at some point that exec is the right place to do it,
> > but what I get is that because this is the container_init task
> > we are OK !
> > A bit clarification would help here ...
>
>
> Well the parent doesn't much matter.  But the child must have a fresh
> start on all the groups of processes.  As all other groupings known by
> a pid are per pspace, so they can't cross that line.

Now, on which kernel does this compile/work ?
Do you have a "helper" program you can share that starts/exec's an
app under a new container (uhmm, namespace). No point for us to
actually write that..

-- Hubertus


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