Re: [PATCH 01/11] iommu: Add device dma ownership set/release interfaces

Christoph Hellwig
2021-11-15T13:14:42Z

On Mon, Nov 15, 2021 at 10:05:42AM +0800, Lu Baolu wrote:
> +enum iommu_dma_owner {
> + DMA_OWNER_NONE,
> + DMA_OWNER_KERNEL,
> + DMA_OWNER_USER,
> +};
> +

> + enum iommu_dma_owner dma_owner;
> + refcount_t owner_cnt;
> + struct file *owner_user_file;

I'd just overload the ownership into owner_user_file,

NULL -> no owner
(struct file *)1UL) -> kernel
real pointer -> user

Which could simplify a lot of the code dealing with the owner.