[PATCH V7 01/11] iommu/of: Refactor of_iommu_configure() for error handling

[Robin Murphy]

On 27/01/17 18:00, Sricharan wrote:
> Hi Robin,
> 
> [..]
> 
>>>> +const struct iommu_ops *of_iommu_configure(struct device *dev,
>>>> +                       struct device_node *master_np)
>>>> +{
>>>> +    const struct iommu_ops *ops;
>>>> +
>>>> +    if (!master_np)
>>>> +        return NULL;
>>>> +
>>>> +    if (dev_is_pci(dev))
>>>> +        ops = of_pci_iommu_init(to_pci_dev(dev), master_np);
>>>
>>> I gave the whole patch set a try on ThunderX. really_probe() is failing
>>> on dma_configure()->of_pci_iommu_init() for each PCI device.
>>
>> When you say "failing", do you mean cleanly, or with a crash? I've
>> managed to hit __of_match_node() dereferencing NULL from
>> of_iommu_xlate() in a horribly complicated chain of events, which I'm
>> trying to figure out now, and I wonder if the two might be related.
> 
> Sorry that there is crash still. __of_match_node seems to checking
> for NULL arguments , feels like some invalid pointer was passed in.
> Is there any particular sequence to try for this ?

Ah, I did figure it out - it wasn't actually a NULL dereference, but an
unmapped address. Turns out __iommu_of_table is in initdata, so any
driver probing after init, connected to an unprobed IOMMU (in this case
disabled in DT), trips over trying to match the now-freed table. I'm
working on the fix - technically the bug's in my patch (#2) anyway ;)

Robin.

> 
> Regards,
>  Sricharan
> 
> 
> 
>