Re: [PATCH v7 07/10] iommu/dma-reserved-iommu: delete bindings in iommu_free_reserved_iova_domain

[Robin Murphy]

On 19/04/16 17:56, Eric Auger wrote:
> Now reserved bindings can exist, destroy them when destroying
> the reserved iova domain. iommu_map is not supposed to be atomic,
> hence the extra complexity in the locking.
>
> Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
>
> ---
> v6 -> v7:
> - remove [PATCH v6 7/7] dma-reserved-iommu: iommu_unmap_reserved and
>    destroy the bindings in iommu_free_reserved_iova_domain
>
> v5 -> v6:
> - use spin_lock instead of mutex
>
> v3 -> v4:
> - previously "iommu/arm-smmu: relinquish reserved resources on
>    domain deletion"
> ---
>   drivers/iommu/dma-reserved-iommu.c | 34 ++++++++++++++++++++++++++++------
>   1 file changed, 28 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/iommu/dma-reserved-iommu.c b/drivers/iommu/dma-reserved-iommu.c
> index 426d339..2522235 100644
> --- a/drivers/iommu/dma-reserved-iommu.c
> +++ b/drivers/iommu/dma-reserved-iommu.c
> @@ -157,14 +157,36 @@ void iommu_free_reserved_iova_domain(struct iommu_domain *domain)
>   	unsigned long flags;
>   	int ret = 0;
>
> -	spin_lock_irqsave(&domain->reserved_lock, flags);
> -
> -	rid = (struct reserved_iova_domain *)domain->reserved_iova_cookie;
> -	if (!rid) {
> -		ret = -EINVAL;
> -		goto unlock;
> +	while (1) {
> +		struct iommu_reserved_binding *b;
> +		struct rb_node *node;
> +		dma_addr_t iova;
> +		size_t size;
> +
> +		spin_lock_irqsave(&domain->reserved_lock, flags);
> +
> +		rid = (struct reserved_iova_domain *)
> +				domain->reserved_iova_cookie;

Same comment about casting as before.

> +		if (!rid) {
> +			ret = -EINVAL;
> +			goto unlock;
> +		}
> +
> +		node = rb_first(&domain->reserved_binding_list);
> +		if (!node)
> +			break;
> +		b = rb_entry(node, struct iommu_reserved_binding, node);
> +
> +		iova = b->iova;
> +		size = b->size;
> +
> +		while (!kref_put(&b->kref, reserved_binding_release))
> +			;

Since you're freeing the thing anyway, why not just call the function 
directly?

> +		spin_unlock_irqrestore(&domain->reserved_lock, flags);
> +		iommu_unmap(domain, iova, size);
>   	}
>
> +	domain->reserved_binding_list = RB_ROOT;
>   	domain->reserved_iova_cookie = NULL;
>   unlock:
>   	spin_unlock_irqrestore(&domain->reserved_lock, flags);