On Wed, Jun 13, 2018 at 11:48:09AM +0200, Thomas Gleixner wrote:
> On Tue, 12 Jun 2018, Ricardo Neri wrote:
> > + /* There are no CPUs to monitor. */
> > + if (!cpumask_weight(&hdata->monitored_mask))
> > + return NMI_HANDLED;
> > +
> > inspect_for_hardlockups(regs);
> >
> > + /*
> > + * Target a new CPU. Keep trying until we find a monitored CPU. CPUs
> > + * are addded and removed to this mask at cpu_up() and cpu_down(),
> > + * respectively. Thus, the interrupt should be able to be moved to
> > + * the next monitored CPU.
> > + */
> > + spin_lock(&hld_data->lock);
>
> Yuck. Taking a spinlock from NMI ...
I am sorry. I will look into other options for locking. Do you think rcu_lock
would help in this case? I need this locking because the CPUs being monitored
changes as CPUs come online and offline.
>
> > + for_each_cpu_wrap(cpu, &hdata->monitored_mask, smp_processor_id() + 1) {
> > + if (!irq_set_affinity(hld_data->irq, cpumask_of(cpu)))
> > + break;
>
> ... and then calling into generic interrupt code which will take even more
> locks is completely broken.
I will into reworking how the destination of the interrupt is set.
Thanks and BR,
Ricardo
