Re: [PATCH] iommu: Fix group refcount in iommu_alloc_default_domain()

[Joerg Roedel]

Hi,

On Fri, May 22, 2020 at 06:31:45PM +0530, Sai Prakash Ranjan wrote:
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index a4c2f122eb8b..05f7b77c432f 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1491,6 +1491,7 @@ static int iommu_alloc_default_domain(struct device *dev)
>  {
>  	struct iommu_group *group;
>  	unsigned int type;
> +	int ret;
>  
>  	group = iommu_group_get(dev);
>  	if (!group)
> @@ -1501,7 +1502,11 @@ static int iommu_alloc_default_domain(struct device *dev)
>  
>  	type = iommu_get_def_domain_type(dev);
>  
> -	return iommu_group_alloc_default_domain(dev->bus, group, type);
> +	ret = iommu_group_alloc_default_domain(dev->bus, group, type);
> +
> +	iommu_group_put(group);
> +
> +	return ret;
>  }
>  
>  /**

Thanks for the report and the fix. I think it is better to fix this by
not taking a group reference in iommu_alloc_default_domain() at all and
pass group as a parameter. Please see the patch I just sent out.

Regards,

	Joerg