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Re: [Xen-devel] [PATCH] xc_save: ignore the first suspend event channel

To: Brendan Cully <brendan@xxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] xc_save: ignore the first suspend event channel notification
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Mon, 08 Sep 2008 11:18:48 +0100
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On 7/9/08 03:28, "Brendan Cully" <brendan@xxxxxxxxx> wrote:

> I could certainly code this up as well (it'd need a static flag in
> evtchn_suspend as well to avoid resignalling the domain, I think). But
> generally without clearing the event channel before signalling the
> guest, the first suspend attempt will always return early. I'm not
> really clear on the scenario that results in the domain not being
> suspended after *suspend has succesfully returned. Could you clarify?

I checked in your patch as is. One question: do we need the
wait-one-second-for-shutdown loop in suspend_and_state() at all? My reading
of (*suspend)() is that it should be sure the domain is suspended when it
returns, and hence should suspend_and_state() not simply raise an error if
it finds that domaininfo does not indicate the guest is shut down? The retry
loop may simply be allowing bugs of the sort you've just fixed to linger.

 -- Keir

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