Re: [Xen-devel] [PATCH] xen/sched: fix cpu offlining with core scheduling

[Jürgen Groß <jgross@xxxxxxxx>]

On 03.03.20 17:05, Jürgen Groß wrote:
> On 03.03.20 14:45, Jan Beulich wrote:
> > On 03.03.2020 13:30, Juergen Gross wrote:
> > > @@ -2538,7 +2552,10 @@ static void sched_slave(void)
> > >       next = sched_wait_rendezvous_in(prev, &lock, cpu, now);
> > >       if ( !next )
> > > +    {
> > > +        rcu_read_unlock(&sched_res_rculock);
> > >           return;
> > > +    }
> > This and ...
> >
> > > @@ -2599,7 +2616,10 @@ static void schedule(void)
> > >           cpumask_raise_softirq(mask, SCHED_SLAVE_SOFTIRQ);
> > >           next = sched_wait_rendezvous_in(prev, &lock, cpu, now);
> > >           if ( !next )
> > > +        {
> > > +            rcu_read_unlock(&sched_res_rculock);
> > >               return;
> > > +        }
> > ... this look like independent fixes, as on Arm,
> > sched_wait_rendezvous_in() can already return NULL. If they get
> > folded into here, I think the description should clarify that
> > these are orthogonal to the rest.
> Yeah, probably better to split the patch.
Oh, this patch was wrong: Up to now sched_wait_rendezvous_in() always
was responsible for dropping sched_res_rculock, so I should do that in
the new NULL return case, too.

So no patch splitting, but V2.


Juergen

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