Re: [Xen-devel] Wrong cpupool handling

[Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxx>]

Am Dienstag 11 November 2014, 15:21:01 schrieb Juergen Gross:
> Hi again,
> 
> On 11/11/2014 01:18 PM, Dietmar Hahn wrote:
> > Hi list,
> >
> > When creating a cpupool, starting and destroying a guest within this pool,
> > then removing this pool doesn't work because of EBUSY.
> >
> > It seems the cause of this behavior is the commit
> > bac6334b51d9bcfe57ecf4a4cb5288348fcf044a.
> >
> > In domain_kill() the function sched_move_domain() gets called changing the
> > d->cpupool pointer to the new cpupool without incrementing/decrementing the
> > counters "n_dom" of the new/old cpupool.
> >
> > This leads to decrementing the wrong  cpupool0->n_dom counter when
> > cpupool_rm_domain() gets called at the end and my own cpupool can't be
> > destroyed because n_dom = 1!
> >
> > I don't have a fast patch because I'am not enough familiar with the code
> > this time but I think it should be fixed for 4.5.
> 
> Please discard previous patch, try this one.

Yes this patch works.
But I think in general a better solution would be to have the changing of the
cpupool pointer in sched_move_domain() together with the increment/decrement
of the counters but I see the locking problem.
Thanks.

Dietmar.

> 
> Juergen
> 

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