On 09/08/17 23:29, Joerg Roedel wrote:
> From: Joerg Roedel <jroe...@suse.de>
> 
> Add a struct iommu_device to each tegra-smmu and register it
> with the iommu-core. Also link devices added to the driver
> to their respective hardware iommus.
> 
> Signed-off-by: Joerg Roedel <jroe...@suse.de>
> ---
>  drivers/iommu/tegra-smmu.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
> index faa9c1e..2802e12 100644
> --- a/drivers/iommu/tegra-smmu.c
> +++ b/drivers/iommu/tegra-smmu.c
> @@ -36,6 +36,8 @@ struct tegra_smmu {
>       struct list_head list;
>  
>       struct dentry *debugfs;
> +
> +     struct iommu_device iommu;      /* IOMMU Core code handle */
>  };
>  
>  struct tegra_smmu_as {
> @@ -720,6 +722,9 @@ static int tegra_smmu_add_device(struct device *dev)
>                        * first match.
>                        */
>                       dev->archdata.iommu = smmu;
> +
> +                     iommu_device_link(&smmu->iommu, dev);
> +
>                       break;
>               }
>  
> @@ -737,6 +742,11 @@ static int tegra_smmu_add_device(struct device *dev)
>  
>  static void tegra_smmu_remove_device(struct device *dev)
>  {
> +     struct tegra_smmu *smmu = dev->archdata.iommu;
> +
> +     if (smmu)
> +             iommu_device_unlink(&smmu->iommu, dev);
> +
>       dev->archdata.iommu = NULL;
>       iommu_group_remove_device(dev);
>  }
> @@ -943,6 +953,18 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
>       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);
> +
> +     iommu_device_set_ops(&smmu->iommu, &tegra_smmu_ops);
> +
> +     err = iommu_device_register(&smmu->iommu);
> +     if (err) {
> +             iommu_device_sysfs_remove(&smmu->iommu);
> +             return ERR_PTR(err);
> +     }
> +
>       if (IS_ENABLED(CONFIG_DEBUG_FS))
>               tegra_smmu_debugfs_init(smmu);
>  
> @@ -951,6 +973,9 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
>  
>  void tegra_smmu_remove(struct tegra_smmu *smmu)
>  {
> +     iommu_device_unregister(&smmu->iommu);
> +     iommu_device_sysfs_remove(&smmu->iommu);
> +
>       if (IS_ENABLED(CONFIG_DEBUG_FS))
>               tegra_smmu_debugfs_exit(smmu);
>  }
> 

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.

You can see the full crash log here [1].

Cheers
Jon

[0] https://nvtb.github.io//linux-next/
[1]
https://nvtb.github.io//linux-next/test_next-20170829/20170829024534/boot/tegra124-jetson-tk1/tegra124-jetson-tk1/tegra_defconfig_log.txt

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