Re: [PATCH 3/8] iommu: Factor out a "first device in group" helper

[Jason Gunthorpe <jgg@nvidia.com>]

On Thu, Jan 19, 2023 at 07:18:21PM +0000, Robin Murphy wrote:
> This pattern for picking the first device out of the group list is
> repeated a few times now, so it's clearly worth factoring out.
> 
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> ---
>  drivers/iommu/iommu.c | 22 ++++++++++------------
>  1 file changed, 10 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index bc53ffbba4de..5b37766a09e2 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1084,6 +1084,11 @@ void iommu_group_remove_device(struct device *dev)
>  }
>  EXPORT_SYMBOL_GPL(iommu_group_remove_device);
>  
> +static struct device *iommu_group_first_dev(struct iommu_group *group)
> +{

Add a
 lockdep_assert_held(&group->lock);

?

> -	group->blocking_domain =
> -		__iommu_domain_alloc(dev->dev->bus, IOMMU_DOMAIN_BLOCKED);
> +	group->blocking_domain = __iommu_domain_alloc(dev->bus, IOMMU_DOMAIN_BLOCKED);
>  	if (!group->blocking_domain) {
>  		/*
>  		 * For drivers that do not yet understand IOMMU_DOMAIN_BLOCKED
>  		 * create an empty domain instead.
>  		 */
> -		group->blocking_domain = __iommu_domain_alloc(
> -			dev->dev->bus, IOMMU_DOMAIN_UNMANAGED);
> +		group->blocking_domain = __iommu_domain_alloc(dev->bus, IOMMU_DOMAIN_UNMANAGED);
>  		if (!group->blocking_domain)
>  			return -EINVAL;

These are extra hunks?

Jason