Re: [PATCH 1/2] iommu/tegra: Add support for struct iommu_device

Jon Hunter
2017-08-30T14:22:05Z

Hi Joerg,

On 30/08/17 13:09, Joerg Roedel wrote:
> Hi Jon,
>
> On Wed, Aug 30, 2017 at 12:04:38PM +0100, Jon Hunter wrote:
>> With next-20170829 I am seeing several Tegra boards crashing [0][1] on
>> boot in tegra_smmu_probe() and the bisect is point to this commit. Looks
>> like there maybe a sequence problem between calls to bus_set_iommu() and
>> iommu_device_add_sysfs() which results in a NULL pointer dereference.
>
> Thanks for the report. Can you please test whether the patch below
> fixes the problem?
>
> Thanks,
>
> Joerg
>
> diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
> index 2802e12e6a54..48ffbe95a663 100644
> --- a/drivers/iommu/tegra-smmu.c
> +++ b/drivers/iommu/tegra-smmu.c
> @@ -949,10 +949,6 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
>
> tegra_smmu_ahb_enable();
>
> - err = bus_set_iommu(&platform_bus_type, &tegra_smmu_ops);
> - if (err < 0)
> - return ERR_PTR(err);
> -
> err = iommu_device_sysfs_add(&smmu->iommu, dev, NULL, dev_name(dev));
> if (err)
> return ERR_PTR(err);
> @@ -965,6 +961,10 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
> return ERR_PTR(err);
> }
>
> + err = bus_set_iommu(&platform_bus_type, &tegra_smmu_ops);
> + if (err < 0)
> + return ERR_PTR(err);
> +

Yes I can confirm that this fixes the crash. I assume that you will fix
the error path for bus_set_iommu() above as I believe now it needs to
call iommu_device_sysfs_remove().

Cheers!
Jon

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