[Xen-devel] Re: [PATCH] Require that xenstored writes to a domain complete in a single chunk

[David Edmondson <dme@xxxxxxx>]

* keir@xxxxxxxxxxxxx [2007-02-26 17:20:34]
> This seems dubious. There's no reason we might not have payloads
> bigger than the ring size (which is only 1kB).

Agreed.

> The right fix would be in the guest, which should already be
> stopping any transactions or commands across save/restore. Does this
> problem occur when xenstored sends an asynchronous watch-fired
> message?

All of the cases I examined (a few dozen) were for watch events.

> Probably the packet-reading thread should be interrupted
> and put to sleep before suspending.

I'll look at this.

> For older guest compatibility perhaps we can take a variant of your
> patch that only waits for enough space is the entire message fits in
> the ring in one go. This would be 'best-effort' at compatibility
> while not precluding use of larger messages in general.

Is the implication that you think that this problem could occur with a
Linux guest (I've never seen it, though have tested much less)?

dme.
-- 
David Edmondson, Sun Microsystems, http://www.dme.org


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