iommu/dma: Refactor iommu_dma_alloc

Shuffle around the self-contained atomic and non-contiguous cases to
return early and get out of the way of the CMA case that we're about to
work on next.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
[hch: slight changes to the code flow]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index a288b3d..4134f13 100644 (file)
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -973,14 +973,19 @@ static void *iommu_dma_alloc(struct device *dev, size_t size,
 {
        bool coherent = dev_is_dma_coherent(dev);
        int ioprot = dma_info_to_prot(DMA_BIDIRECTIONAL, coherent, attrs);
+       pgprot_t prot = arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs);
        size_t iosize = size;
+       struct page *page;
        void *addr;
 
        size = PAGE_ALIGN(size);
        gfp |= __GFP_ZERO;
 
+       if (gfpflags_allow_blocking(gfp) &&
+           !(attrs & DMA_ATTR_FORCE_CONTIGUOUS))
+               return iommu_dma_alloc_remap(dev, iosize, handle, gfp, attrs);
+
        if (!gfpflags_allow_blocking(gfp)) {
-               struct page *page;
                /*
                 * In atomic context we can't remap anything, so we'll only
                 * get the virtually contiguous buffer we need by way of a
@@ -1002,39 +1007,34 @@ static void *iommu_dma_alloc(struct device *dev, size_t size,
                                __free_pages(page, get_order(size));
                        else
                                dma_free_from_pool(addr, size);
-                       addr = NULL;
-               }
-       } else if (attrs & DMA_ATTR_FORCE_CONTIGUOUS) {
-               pgprot_t prot = arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs);
-               struct page *page;
-
-               page = dma_alloc_from_contiguous(dev, size >> PAGE_SHIFT,
-                                       get_order(size), gfp & __GFP_NOWARN);
-               if (!page)
                        return NULL;
-
-               *handle = __iommu_dma_map(dev, page_to_phys(page), iosize, ioprot);
-               if (*handle == DMA_MAPPING_ERROR) {
-                       dma_release_from_contiguous(dev, page,
-                                                   size >> PAGE_SHIFT);
-                       return NULL;
-               }
-               addr = dma_common_contiguous_remap(page, size, VM_USERMAP,
-                                                  prot,
-                                                  __builtin_return_address(0));
-               if (addr) {
-                       if (!coherent)
-                               arch_dma_prep_coherent(page, iosize);
-                       memset(addr, 0, size);
-               } else {
-                       __iommu_dma_unmap(dev, *handle, iosize);
-                       dma_release_from_contiguous(dev, page,
-                                                   size >> PAGE_SHIFT);
                }
-       } else {
-               addr = iommu_dma_alloc_remap(dev, iosize, handle, gfp, attrs);
+               return addr;
        }
+
+       page = dma_alloc_from_contiguous(dev, size >> PAGE_SHIFT,
+                                        get_order(size), gfp & __GFP_NOWARN);
+       if (!page)
+               return NULL;
+
+       *handle = __iommu_dma_map(dev, page_to_phys(page), iosize, ioprot);
+       if (*handle == DMA_MAPPING_ERROR)
+               goto out_free_pages;
+
+       addr = dma_common_contiguous_remap(page, size, VM_USERMAP, prot,
+                       __builtin_return_address(0));
+       if (!addr)
+               goto out_unmap;
+
+       if (!coherent)
+               arch_dma_prep_coherent(page, iosize);
+       memset(addr, 0, size);
        return addr;
+out_unmap:
+       __iommu_dma_unmap(dev, *handle, iosize);
+out_free_pages:
+       dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT);
+       return NULL;
 }
 
 static int __iommu_dma_mmap_pfn(struct vm_area_struct *vma,