[RFC, PATCH] teach utrace to destroy engine->data

[Oleg Nesterov]

On 08/23, Roland McGrath wrote:
>
> > > This model seems like a better fit for ptrace to me.  The anchoring data
> > > structure is the tracer's tracees list, which links together the
> > > ptrace_context structs.  A live ptrace_context has an engine pointer and
> > > a ref for it.
> >
> > OK. Not that I really understand this all in details, but OK.
> >
> > But. Do you think we should do this right now?
>
> If it is the right way to handle the data structure lifetimes, I don't see
> why we would do it any different way first.  One of the main points of what
> makes one plan or another "the right way" is that it makes it easier to get
> the corners right.  So if it's easier to get the corners right another way,
> then maybe that other way is the right one.
>
> > I don't. Imho, we need a lot of changes before this.
>
> I don't understand why you think this.

Simple answer. Because I do not know how to implement this. At least now.
I tried to think of this more, but I don't see how to make the first steps.

(Yes, to be honest, this looks like "unnecessary complication" to me, I have
 to admit. But this is not the reason.)

> > Do you have any suggestion what can we do right now? (assuming you won't
> > apply your ops->release patch).
>
> I didn't say I wouldn't.  I was hoping for some more discussion about it
> and better understanding of the underlying issues that made you want it,
> maybe with some voices other than just yours and mine.

Agreed, but nobody else cares ;)


So, I am going to use the simple ops->release method for now. Once we
have the working code we can reconsider the lifetime rules for engine/
engine->data.

Oleg.