linux-kernel - [PATCH 20/25] iommu/dma: Refactor iommu_dma_get

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Date:   Tue, 30 Apr 2019 06:52:09 -0400
From:   Christoph Hellwig <hch@....de>
To:     Robin Murphy <robin.murphy@....com>
Cc:     Joerg Roedel <joro@...tes.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        iommu@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 20/25] iommu/dma: Refactor iommu_dma_get_sgtable

Inline __iommu_dma_get_sgtable_page 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.

Signed-off-by: Christoph Hellwig <hch@....de>
Reviewed-by: Robin Murphy <robin.murphy@....com>
---
 drivers/iommu/dma-iommu.c | 45 +++++++++++++++------------------------
 1 file changed, 17 insertions(+), 28 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index dc4bf41d0349..5d4013ffd068 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1078,42 +1078,31 @@ static int iommu_dma_mmap(struct device *dev, struct vm_area_struct *vma,
 	return __iommu_dma_mmap(pages, size, vma);
 }
 
-static int __iommu_dma_get_sgtable_page(struct sg_table *sgt, struct page *page,
-		size_t size)
-{
-	int ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
-
-	if (!ret)
-		sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0);
-	return ret;
-}
-
 static int iommu_dma_get_sgtable(struct device *dev, struct sg_table *sgt,
 		void *cpu_addr, dma_addr_t dma_addr, size_t size,
 		unsigned long attrs)
 {
-	unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
-	struct page **pages;
+	struct page *page;
+	int ret;
 
-	if (!is_vmalloc_addr(cpu_addr)) {
-		struct page *page = virt_to_page(cpu_addr);
-		return __iommu_dma_get_sgtable_page(sgt, page, 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.
-		 */
-		struct page *page = vmalloc_to_page(cpu_addr);
-		return __iommu_dma_get_sgtable_page(sgt, page, size);
+		if (pages) {
+			return sg_alloc_table_from_pages(sgt, pages,
+					PAGE_ALIGN(size) >> PAGE_SHIFT,
+					0, size, GFP_KERNEL);
+		}
+
+		page = vmalloc_to_page(cpu_addr);
+	} else {
+		page = virt_to_page(cpu_addr);
 	}
 
-	pages = __iommu_dma_get_pages(cpu_addr);
-	if (!pages)
-		return -ENXIO;
-	return sg_alloc_table_from_pages(sgt, pages, count, 0, size,
-					 GFP_KERNEL);
+	ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
+	if (!ret)
+		sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0);
+	return ret;
 }
 
 static const struct dma_map_ops iommu_dma_ops = {
-- 
2.20.1