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SubjectRe: [PATCH 22/26] iommu/dma: Refactor iommu_dma_mmap
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On 22/04/2019 18:59, Christoph Hellwig wrote:
> Inline __iommu_dma_mmap_pfn into the main function, and use the
> fact that __iommu_dma_get_pages return NULL for remapped contigous
> allocations to simplify the code flow a bit.

...and later we can squash __iommu_dma_mmap() once the dust settles on
vm_map_pages() - seems good to me.

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> drivers/iommu/dma-iommu.c | 36 +++++++++++-------------------------
> 1 file changed, 11 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index 138b85e675c8..8fc6098c1eeb 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -1025,21 +1025,12 @@ static void *iommu_dma_alloc(struct device *dev, size_t size,
> return cpu_addr;
> }
>
> -static int __iommu_dma_mmap_pfn(struct vm_area_struct *vma,
> - unsigned long pfn, size_t size)
> -{
> - return remap_pfn_range(vma, vma->vm_start, pfn + vma->vm_pgoff,
> - vma->vm_end - vma->vm_start,
> - vma->vm_page_prot);
> -}
> -
> static int iommu_dma_mmap(struct device *dev, struct vm_area_struct *vma,
> void *cpu_addr, dma_addr_t dma_addr, size_t size,
> unsigned long attrs)
> {
> unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
> - unsigned long off = vma->vm_pgoff;
> - struct page **pages;
> + unsigned long pfn, off = vma->vm_pgoff;
> int ret;
>
> vma->vm_page_prot = arch_dma_mmap_pgprot(dev, vma->vm_page_prot, attrs);
> @@ -1050,24 +1041,19 @@ static int iommu_dma_mmap(struct device *dev, struct vm_area_struct *vma,
> if (off >= nr_pages || vma_pages(vma) > nr_pages - off)
> return -ENXIO;
>
> - if (!is_vmalloc_addr(cpu_addr)) {
> - unsigned long pfn = page_to_pfn(virt_to_page(cpu_addr));
> - return __iommu_dma_mmap_pfn(vma, pfn, size);
> - }
> + if (is_vmalloc_addr(cpu_addr)) {
> + struct page **pages = __iommu_dma_get_pages(cpu_addr);
>
> - if (attrs & DMA_ATTR_FORCE_CONTIGUOUS) {
> - /*
> - * DMA_ATTR_FORCE_CONTIGUOUS allocations are always remapped,
> - * hence in the vmalloc space.
> - */
> - unsigned long pfn = vmalloc_to_pfn(cpu_addr);
> - return __iommu_dma_mmap_pfn(vma, pfn, size);
> + if (pages)
> + return __iommu_dma_mmap(pages, size, vma);
> + pfn = vmalloc_to_pfn(cpu_addr);
> + } else {
> + pfn = page_to_pfn(virt_to_page(cpu_addr));
> }
>
> - pages = __iommu_dma_get_pages(cpu_addr);
> - if (WARN_ON_ONCE(!pages))
> - return -ENXIO;
> - return __iommu_dma_mmap(pages, size, vma);
> + return remap_pfn_range(vma, vma->vm_start, pfn + off,
> + vma->vm_end - vma->vm_start,
> + vma->vm_page_prot);
> }
>
> static int iommu_dma_get_sgtable(struct device *dev, struct sg_table *sgt,
>

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