On 08/08/17 11:26, Artem Savkov wrote:
> Commit c54451a "iommu/arm-smmu: Fix the error path in arm_smmu_add_device"
> removed fwspec assignment in legacy_binding path as redundant which is
> wrong. It needs to be updated after fwspec initialisation in
> arm_smmu_register_legacy_master() as it is dereferenced later. Without
> this there is a NULL-pointer dereference panic during boot on some hosts.

Reviewed-by: Robin Murphy <robin.mur...@arm.com>

Thanks for fixing it up, and sorry for failing to document the
unfortunately subtle logic in the first place!

Robin.

> Signed-off-by: Artem Savkov <asav...@redhat.com>
> ---
>  drivers/iommu/arm-smmu.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index b97188a..2d80fa8 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -1519,6 +1519,13 @@ static int arm_smmu_add_device(struct device *dev)
>  
>       if (using_legacy_binding) {
>               ret = arm_smmu_register_legacy_master(dev, &smmu);
> +
> +             /*
> +              * If dev->iommu_fwspec is initally NULL, 
> arm_smmu_register_legacy_master()
> +              * will allocate/initialise a new one. Thus we need to update 
> fwspec for
> +              * later use.
> +              */
> +             fwspec = dev->iommu_fwspec;
>               if (ret)
>                       goto out_free;
>       } else if (fwspec && fwspec->ops == &arm_smmu_ops) {
> 

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