[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] xc_save: ignore the first suspend event channel notification
On Monday, 08 September 2008 at 11:18, Keir Fraser wrote: > 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. I agree that that retry loop is a bit dubious. It appears to come from changeset 2147:949f21fc9e77 (Fix migrate to cope with domains that are paused.) This was long before device migration appeared in xend (changeset 9657:1fe63743a147), when the only thing that mattered was that the domain be suspended before the final round. Removing the poll in suspend_and_state undoes 2147. If we want to keep that logic, we could probably just hoist it up into *suspend. There's still no protection that I know of between concurrent invocation of xc_save on the same domain, but that's a whole other kettle of fish :) _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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