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SubjectRe: [PATCH v3 2/2] irqchip: dw-apb-ictl: add irq_set_affinity support
On Mon, 6 Jul 2015, Jisheng Zhang wrote:
> On Mon, 6 Jul 2015 12:30:01 +0200
> Thomas Gleixner <tglx@linutronix.de> wrote:
>
> > On Mon, 6 Jul 2015, Jisheng Zhang wrote:
> > > +static int dw_apb_ictl_set_affinity(struct irq_data *d,
> > > + const struct cpumask *mask_val,
> > > + bool force)
> > > +{
> > > + struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
> > > + struct dw_apb_ictl_priv *priv = gc->private;
> > > + struct irq_chip *chip = irq_get_chip(priv->parent_irq);
> > > + struct irq_data *data = irq_get_irq_data(priv->parent_irq);
> > > +
> > > + if (chip && chip->irq_set_affinity)
> > > + return chip->irq_set_affinity(data, mask_val, force);
> >
> > This is wrong as it lacks proper locking of the parent irq. That needs
> > to be solved at the core code level in a clean way.
>
> Is it acceptable to call irq_set_affinity() or irq_force_affinity() as the
> following:
>
> if (force)
> return irq_force_affinity(priv->parent_irq, mask_val);
> else
> return irq_set_affinity(priv->parent_irq, mask_val);

Not from the driver, as you run into lock nesting hell. As I said,
this needs to be solved at the core code level and needs a proper
thought out design.

Just for the record: I'm not too happy about that 'fiddle with the
parent' mechanism because it opens just a large can of worms. I wish
hardware designers would talk to OS people before they implement random
nonsense.

Thanks,

tglx




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