Re: [PATCH] x86, irq: Check if irq is remapped before freeing irte

From: Yinghai
Date: Mon Oct 18 2010 - 17:30:28 EST




On Oct 18, 2010, at 2:17 PM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:

>
>
> On Mon, 18 Oct 2010, Thomas Gleixner wrote:
>
>> On Mon, 18 Oct 2010, Yinghai Lu wrote:
>>>
>>> Index: linux-2.6/drivers/pci/intr_remapping.c
>>> ===================================================================
>>> --- linux-2.6.orig/drivers/pci/intr_remapping.c
>>> +++ linux-2.6/drivers/pci/intr_remapping.c
>>> @@ -60,7 +60,7 @@ int get_irte(int irq, struct irte *entry
>>> unsigned long flags;
>>> int index;
>>>
>>> - if (!entry || !irq_iommu)
>>> + if (!entry || !irq_iommu || !irq_iommu->iommu)
>>> return -1;
>>
>> Hmm, why do we need this? This is only called from
>> ir_ioapic_set_affinity() and ir_msi_set_affinity().
>>
>> We should never end up there when intr_remapping=off, right ?
>
> Thinking more about it, this check is actively bogus. The call sites do:
>
> struct irte irte;
>
> if (get_irte(irq, &irte))
> return -1;
>
> So entry _CANNOT_ be NULL.
>
> And in fact we should change get_irte() to
>
> get_irte(struct irq_2_iommu *irq_iommu, struct irte *entry)
>
> The call site already knows about it. No need to lookup irq_iommu
> based on the irq number.

Yes
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