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Re: [Xen-devel] [PATCH 3/5] libxl: add support for vscsi

On Wed, Feb 03, 2016 at 02:36:03PM +0000, Wei Liu wrote:
> (Note that I'm not very familiar with this, so what I'm talking might be
> non-sense, and please bear with me if I ask stupid questions.)
> On Wed, Jan 27, 2016 at 11:00:12AM +0100, Olaf Hering wrote:
> > On Fri, Nov 13, Olaf Hering wrote:
> > 
> > > Port pvscsi support from xend to libxl:
> > 
> > How should code which converts devices from xenstore to json handle
> > devices which got marked as "to be removed"?
> > 
> > In my pvscsi code I set XenbusStateClosing in the vscsidev, then
> > XenbusStateReconfiguring in vscsictrl. This causes the backend/frontend
> > to reevaluate the vscsi bus. During that timeframe some other code can
> > walk xenstore and find such a device. In libxl__vscsi_fill_host below
> > such device gets the ->remove flag. This flag is handled elsewhere to
> > indicate that its not an active device anymore. IanC asked to remove the
> > flag and I'm converting the code to work without such flag. The question
> > still stands what to do with such devices when filling the list of
> > vscsidevs on a vscsictrl. Is it up to the caller to inspect the state of
> > each vscsidev to decide what to do with it? Or should the function below
> > just skip the device right away?
> > 
> > I think in the current state the device would endup in d_config and in json.
> > 
> If it is to be removed, why don't you just filter it out and not have it
> in JSON at all? This is provided libxl won't rely on that to do proper
> clean-up I don't see the value of retaining them, and if libxl is
> relying on the JSON file to do clean-up the design is probably wrong.
> In the mean time I will start (re-)reading this vscsi thing...

BTW if you plan to post a new version please just go ahead. Don't wait
for me to comment on this version.


> Wei.

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