Re: [Xen-devel] domains not shutting down properly - theproblemisback again

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 02/01/2009 09:11, "James Harper" <james.harper@xxxxxxxxxxxxxxxx> wrote:

>> The only thing that seems to make a difference is:
>> 
>> /etc/init.d/xend stop
>> killall xenstored
>> /etc/init.d/xend start
>> 
>> Once I do that, everything works perfectly. Now I guess I just have to
>> try and find out what is different between starting it on a freshly
>> booted system vs restarting it...
> 
> Just to clarify, by 'everything works perfectly' I mean that a domain
> that doesn't have any vif or vbd interfaces (just a 'kernel=' line for
> testing), crashes and cleans up after itself, as opposed to crashing and
> hanging around. Restarting xenstored obviously breaks the connection to
> the Dom0 backend drivers.

Yeah, I was going to say... :-)

Anyway, your observations can be explained by the fact that the restarted
xenstored will not auto-connect to any domain. So since it holds no
resources of the domU, it won't impede the domU's destruction.

Xenstored is supposed to receive a VIRQ_DOM_EXC when a domain is killed (see
xen/common/domain.c:domain_kill(). This should trigger
xenstored_domain.c:domain_cleanup() which queries every domain it knows
about and if it sees XEN_DOMINF_dying (which gets cooked in libxenctrl into
boolean flag dominfo.dying) then it should talloc_free() the domain state
and hence release resources. These are the paths you need to log.

 -- Keir



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