Re: [Xen-devel] [PATCH v1 12/12] libxl: add device backend listener in order to launch backends

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2013-11-07 at 16:35 +0000, Ian Jackson wrote:
> Ian Campbell writes ("Re: [PATCH v1 12/12] libxl: add device backend listener 
> in order to launch backends"):
> > On Mon, 2013-11-04 at 17:59 +0000, Ian Jackson wrote:
> > > +    assert(parent->magic == LIBXL__AO_MAGIC);
> > 
> > Is the intention to allow multiple levels of nesting or would it be a
> > good idea to have an assert(!parent->nested) here?
> 
> I don't think there is anything wrong with multiple levels of nesting
> although I'm hoping no-one will find a use for it!

Indeed!

> > In either case it would be good to be explicit in the comment, either
> > here or in the header.
> 
> Sure.

OK. I trust you will write something sensible, so here is a preemptive:
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

Use it wisely ;-)

> [...]
> If there is no first-class ao running, then nothing might be running
> the libxl event loop and the "escaped" sub-ao might never make
> progress.
> 
> So the requirement is there to stop people writing a broken daemonic
> sub-ao (ie, one which outlives its parent).  It's slightly stricter
> than the actual requirement for correctness, which is that _some_ ao
> must still continue.  But I'm hoping that no-one wants to have some
> more complicated semantic relationship between a sub-ao and the
> system's real ao's than parenthood.

Makes sense.

Ian



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