On Sun, May 17, 2015 at 03:19:34PM +1000, NeilBrown wrote: > > > Nested IRQs can only fire when the parent irq fires. > So when the parent is suspended, there is no need to suspend > the child irq. > > Suspending nested irqs can cause a problem is they are suspended or > resumed in the wrong order. > If an interrupt fires while the parent is active but the child is > suspended, then the interrupt will not be acknowledged properly > and so an interrupt storm can result. > This is particularly likely if the parent is resumed before > the child, and the interrupt was raised during suspend. > > Ensuring correct ordering would be possible, but it is simpler > to just never suspend nested interrupts.
Looks sane to me, but it's Thomas' call. FWIW: Acked-by: Peter Zijlstra (Intel) <pet...@infradead.org> > > Signed-off-by: NeilBrown <n...@brown.name> > --- > diff --git a/kernel/irq/pm.c b/kernel/irq/pm.c > index 5204a6d1b985..d22786a6dbde 100644 > --- a/kernel/irq/pm.c > +++ b/kernel/irq/pm.c > @@ -123,6 +123,8 @@ void suspend_device_irqs(void) > unsigned long flags; > bool sync; > > + if (irq_settings_is_nested_thread(desc)) > + continue; > raw_spin_lock_irqsave(&desc->lock, flags); > sync = suspend_device_irq(desc, irq); > raw_spin_unlock_irqrestore(&desc->lock, flags); > @@ -163,6 +165,8 @@ static void resume_irqs(bool want_early) > > if (!is_early && want_early) > continue; > + if (irq_settings_is_nested_thread(desc)) > + continue; > > raw_spin_lock_irqsave(&desc->lock, flags); > resume_irq(desc, irq); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
