On Saturday, January 31, 2015 09:25:45 AM 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. This patch does that.
Clever. :-) This is fine by me. Thomas, what do you think? > This patch allows the IRQF_EARLY_RESUME to be removed from > twl4030_sih_setup(). That flag attempts to fix the same problem > is a very different way, but causes > > [ 56.095825] WARNING: CPU: 0 PID: 3 at ../kernel/irq/manage.c:661 > irq_nested_primary_handler+0x18/0x28() > [ 56.095825] Primary handler called for nested irq 348 > > warnings on resume. > > Signed-off-by: NeilBrown <n...@brown.name> > > diff --git a/kernel/irq/pm.c b/kernel/irq/pm.c > index 3ca532592704..40cbcfb7fc43 100644 > --- a/kernel/irq/pm.c > +++ b/kernel/irq/pm.c > @@ -118,6 +118,8 @@ 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); > @@ -158,6 +160,8 @@ 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); -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.
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