Re: [PATCH 3/5] sched/deadline: Fix wrong cpudl_find() in check_preempt_equal_dl()

Peter Zijlstra
2015-01-27T14:15:57Z

On Tue, Jan 27, 2015 at 01:48:15PM +0100, Peter Zijlstra wrote:
> On Mon, Jan 19, 2015 at 04:49:38AM +0000, Xunlei Pang wrote:
> > +++ b/kernel/sched/deadline.c
> > @@ -943,14 +943,23 @@ out:
> > return cpu;
> > }
> >
> > +static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask_dl);
> > +
> > static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p)
> > {
> > + struct cpumask *later_mask =
> > + this_cpu_cpumask_var_ptr(local_cpu_mask_dl);
> > +
> > + /* Make sure the mask is initialized first */
> > + if (unlikely(!later_mask))
> > + return;
> > +
> > /*
> > * Current can't be migrated, useless to reschedule,
> > * let's hope p can move out.
> > */
> > if (rq->curr->nr_cpus_allowed == 1 ||
> > - cpudl_find(&rq->rd->cpudl, rq->curr, NULL) == -1)
> > + cpudl_find(&rq->rd->cpudl, rq->curr, later_mask) == -1)
> > return;
> >
> > /*
>
> But but, should you not put something in that mask before you use it?

N/M I can't read.