On Thu, 2007-10-04 at 11:34 +0200, Philippe Gerum wrote:
> > Well, this trace also reveals a second bug that can cause nasty priority
> > inversion: a high-prio domains executes when a fasteoi-IRQ arrives for a
> > low-prio domain. This will now block all IRQs until the low-prio domain
> > was able to run its IRQ handler completely. Thus we must _mask_ fasteoi
> > IRQs for low-prio domains while high-prio ones are running!
> >
>
> This code was actually there up to 2.6.17-1.5-02, and was removed at
> some point in the 2.6.19 series, due to some severe conflicts with the
> vanilla IO-APIC support which used to be a hell of a moving target at
> that time. I guess it's time to bring this code back.
>
Does the following work for you?
diff --git a/arch/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c
index 2ae79e9..517937b 100644
--- a/arch/i386/kernel/io_apic.c
+++ b/arch/i386/kernel/io_apic.c
@@ -2022,6 +2022,8 @@ static void ack_ioapic_quirk_irq(unsigned int irq)
__unmask_and_level_IO_APIC_irq(irq);
spin_unlock(&ioapic_lock);
}
+
+ __mask_IO_APIC_irq(irq);
}
static int ioapic_retrigger_irq(unsigned int irq)
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index ba497a7..1560b4a 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -422,8 +422,13 @@ handle_fasteoi_irq(unsigned int irq, struct irq_desc *desc)
spin_lock(&desc->lock);
desc->status &= ~IRQ_INPROGRESS;
+#ifdef CONFIG_IPIPE
+ desc->chip->unmask(irq);
+out:
+#else
out:
desc->chip->eoi(irq);
+#endif
spin_unlock(&desc->lock);
}
@@ -533,11 +538,12 @@ void fastcall __ipipe_end_level_irq(unsigned irq, struct
irq_desc *desc)
void fastcall __ipipe_ack_fasteoi_irq(unsigned irq, struct irq_desc *desc)
{
+ desc->chip->eoi(irq);
}
void fastcall __ipipe_end_fasteoi_irq(unsigned irq, struct irq_desc *desc)
{
- desc->chip->eoi(irq);
+ desc->chip->unmask(irq);
}
void fastcall __ipipe_ack_edge_irq(unsigned irq, struct irq_desc *desc)
--
Philippe.
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