Subject: Re: [PATCH v6 05/20] dma: swiotlb: pass mapping attributes by reference

From: Petr Tesarik <[email-masked]>
Date: Tue, 9 Jun 2026 14:21:22 +0200

On Thu,  4 Jun 2026 14:09:44 +0530
"Aneesh Kumar K.V (Arm)" <[email-masked]> wrote:

> Change swiotlb_tbl_map_single() to take the DMA mapping attributes by
> reference and update the direct callers accordingly.
> 
> This is a preparatory change for a follow-up patch which updates the
> attributes based on the selected swiotlb pool. Keeping the signature change
> separate makes the follow-up patch easier to review.
> 
> No functional change in this patch.
> 
> Tested-by: Michael Kelley <[email-masked]>
> Tested-by: Mostafa Saleh <[email-masked]>
> Signed-off-by: Aneesh Kumar K.V (Arm) <[email-masked]>

Reviewed-by: Petr Tesarik <[email-masked]>

Thanks
Petr T

> ---
>  drivers/iommu/dma-iommu.c | 2 +-
>  drivers/xen/swiotlb-xen.c | 2 +-
>  include/linux/swiotlb.h   | 2 +-
>  kernel/dma/swiotlb.c      | 6 +++---
>  4 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index c2595bee3d41..725c7adb0a8d 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -1180,7 +1180,7 @@ static phys_addr_t iommu_dma_map_swiotlb(struct device *dev, phys_addr_t phys,
>  	trace_swiotlb_bounced(dev, phys, size);
>  
>  	phys = swiotlb_tbl_map_single(dev, phys, size, iova_mask(iovad), dir,
> -			attrs);
> +				      &attrs);
>  
>  	/*
>  	 * Untrusted devices should not see padding areas with random leftover
> diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> index 2cbf2b588f5b..8c4abe65cd49 100644
> --- a/drivers/xen/swiotlb-xen.c
> +++ b/drivers/xen/swiotlb-xen.c
> @@ -243,7 +243,7 @@ static dma_addr_t xen_swiotlb_map_phys(struct device *dev, phys_addr_t phys,
>  	 */
>  	trace_swiotlb_bounced(dev, dev_addr, size);
>  
> -	map = swiotlb_tbl_map_single(dev, phys, size, 0, dir, attrs);
> +	map = swiotlb_tbl_map_single(dev, phys, size, 0, dir, &attrs);
>  	if (map == (phys_addr_t)DMA_MAPPING_ERROR)
>  		return DMA_MAPPING_ERROR;
>  
> diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
> index 133bb8ca9032..29187cec90d8 100644
> --- a/include/linux/swiotlb.h
> +++ b/include/linux/swiotlb.h
> @@ -238,7 +238,7 @@ static inline phys_addr_t default_swiotlb_limit(void)
>  
>  phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t phys,
>  		size_t mapping_size, unsigned int alloc_aligned_mask,
> -		enum dma_data_direction dir, unsigned long attrs);
> +		enum dma_data_direction dir, unsigned long *attrs);
>  dma_addr_t swiotlb_map(struct device *dev, phys_addr_t phys,
>  		size_t size, enum dma_data_direction dir, unsigned long attrs);
>  
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index be4d418d92ac..78ce05857c00 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -1391,7 +1391,7 @@ static unsigned long mem_used(struct io_tlb_mem *mem)
>   */
>  phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr,
>  		size_t mapping_size, unsigned int alloc_align_mask,
> -		enum dma_data_direction dir, unsigned long attrs)
> +		enum dma_data_direction dir, unsigned long *attrs)
>  {
>  	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
>  	unsigned int offset;
> @@ -1425,7 +1425,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr,
>  	size = ALIGN(mapping_size + offset, alloc_align_mask + 1);
>  	index = swiotlb_find_slots(dev, orig_addr, size, alloc_align_mask, &pool);
>  	if (index == -1) {
> -		if (!(attrs & DMA_ATTR_NO_WARN))
> +		if (!(*attrs & DMA_ATTR_NO_WARN))
>  			dev_warn_ratelimited(dev,
>  	"swiotlb buffer is full (sz: %zd bytes), total %lu (slots), used %lu (slots)\n",
>  				 size, mem->nslabs, mem_used(mem));
> @@ -1604,7 +1604,7 @@ dma_addr_t swiotlb_map(struct device *dev, phys_addr_t paddr, size_t size,
>  
>  	trace_swiotlb_bounced(dev, phys_to_dma(dev, paddr), size);
>  
> -	swiotlb_addr = swiotlb_tbl_map_single(dev, paddr, size, 0, dir, attrs);
> +	swiotlb_addr = swiotlb_tbl_map_single(dev, paddr, size, 0, dir, &attrs);
>  	if (swiotlb_addr == (phys_addr_t)DMA_MAPPING_ERROR)
>  		return DMA_MAPPING_ERROR;
>