Re: [Xen-devel] [hypervisor deadlock] Re: [PATCH v9 for Xen 4.7 1/4] xen: enable per-VCPU parameter for RTDS

[Dario Faggioli <dario.faggioli@xxxxxxxxxx>]

On Mon, 2016-04-04 at 17:05 +0100, George Dunlap wrote:
> On 04/04/16 16:58, Chong Li wrote:
> > On Mon, Apr 4, 2016 at 10:14 AM, Andrew Cooper
> > <andrew.cooper3@xxxxxxxxxx> wrote:
> > > On 01/04/16 05:59, Chong Li wrote:
> > > > 
> > > > --- a/xen/common/sched_credit2.c
> > > > +++ b/xen/common/sched_credit2.c
> > > > @@ -1421,14 +1421,12 @@ csched2_dom_cntl(
> > > >       * runq lock to update csvcs. */
> > > >      spin_lock_irqsave(&prv->lock, flags);
> > > > 
> > > > -    if ( op->cmd == XEN_DOMCTL_SCHEDOP_getinfo )
> > > > +    switch ( op->cmd )
> > > >      {
> > > > +    case XEN_DOMCTL_SCHEDOP_getinfo:
> > > >          op->u.credit2.weight = sdom->weight;
> > > > -    }
> > > > -    else
> > > > -    {
> > > > -        ASSERT(op->cmd == XEN_DOMCTL_SCHEDOP_putinfo);
> > > > -
> > > > +        break;
> > > > +    case XEN_DOMCTL_SCHEDOP_putinfo:
> > > >          if ( op->u.credit2.weight != 0 )
> > > >          {
> > > >              struct vcpu *v;
> > > > @@ -1457,6 +1455,9 @@ csched2_dom_cntl(
> > > >                  vcpu_schedule_unlock(lock, svc->vcpu);
> > > >              }
> > > >          }
> > > > +        break;
> > > > +    default:
> > > > +        return -EINVAL;
> > > As does this.
> > > 
> > > Please submit a bugfix ASAP.  This will become a security
> > > vulnerability
> > > if Xen 4.7 is shipped without it being fixed.
> > > 
> > > > 
> > > >      }
> > > > 
> > > >      spin_unlock_irqrestore(&prv->lock, flags);
> > Thanks for pointing this out.
> > 
> > Dario, do you want to include this bugfix in your cleanup patch, or
> > let me submit this?
> If you're around and can test it, it's probably better if you can
> send a
> patch right a way.
> 
Exactly. In fact:
 - we don't fold bugfixes in clanups,
 - I think I mentioned wanting to cleanup some code duplication in 
   libxl, this is in xen,
 - cleanups are delayed to 4.8, while this must be fixed before 
   release (or the patch/the whole feature be reverted).

So, if you can't work out a fix today or, at most, tomorrow, let me
know and I'll do it myself.

Sorry for not catching this during review... :-/

Regards,
Dario
-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)

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