[PATCH 11/26] iommu/dma: Factor out remapped pages lookup

[Christoph Hellwig]

From: Robin Murphy <robin.murphy@xxxxxxx>

Since we duplicate the find_vm_area() logic a few times in places where
we only care aboute the pages, factor out a helper to abstract it.

Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
[hch: don't warn when not finding a region, as we'll rely on that later]
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 drivers/iommu/dma-iommu.c | 32 ++++++++++++++++++++------------
 1 file changed, 20 insertions(+), 12 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index b52c5d6be7b4..8e2d9733113e 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -525,6 +525,15 @@ static struct page **__iommu_dma_alloc_pages(struct device *dev,
 	return pages;
 }
 
+static struct page **__iommu_dma_get_pages(void *cpu_addr)
+{
+	struct vm_struct *area = find_vm_area(cpu_addr);
+
+	if (!area || !area->pages)
+		return NULL;
+	return area->pages;
+}
+
 /**
  * iommu_dma_free - Free a buffer allocated by __iommu_dma_alloc()
  * @dev: Device which owns this buffer
@@ -1023,11 +1032,11 @@ static void iommu_dma_free(struct device *dev, size_t size, void *cpu_addr,
 		dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT);
 		dma_common_free_remap(cpu_addr, size, VM_USERMAP);
 	} else if (is_vmalloc_addr(cpu_addr)){
-		struct vm_struct *area = find_vm_area(cpu_addr);
+		struct page **pages = __iommu_dma_get_pages(cpu_addr);
 
-		if (WARN_ON(!area || !area->pages))
+		if (WARN_ON(!pages))
 			return;
-		__iommu_dma_free(dev, area->pages, iosize, &handle);
+		__iommu_dma_free(dev, pages, iosize, &handle);
 		dma_common_free_remap(cpu_addr, size, VM_USERMAP);
 	} else {
 		__iommu_dma_unmap(dev, handle, iosize);
@@ -1049,7 +1058,7 @@ static int iommu_dma_mmap(struct device *dev, struct vm_area_struct *vma,
 {
 	unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
 	unsigned long off = vma->vm_pgoff;
-	struct vm_struct *area;
+	struct page **pages;
 	int ret;
 
 	vma->vm_page_prot = arch_dma_mmap_pgprot(dev, vma->vm_page_prot, attrs);
@@ -1074,11 +1083,10 @@ static int iommu_dma_mmap(struct device *dev, struct vm_area_struct *vma,
 		return __iommu_dma_mmap_pfn(vma, pfn, size);
 	}
 
-	area = find_vm_area(cpu_addr);
-	if (WARN_ON(!area || !area->pages))
+	pages = __iommu_dma_get_pages(cpu_addr);
+	if (WARN_ON_ONCE(!pages))
 		return -ENXIO;
-
-	return __iommu_dma_mmap(area->pages, size, vma);
+	return __iommu_dma_mmap(pages, size, vma);
 }
 
 static int __iommu_dma_get_sgtable_page(struct sg_table *sgt, struct page *page,
@@ -1096,7 +1104,7 @@ static int iommu_dma_get_sgtable(struct device *dev, struct sg_table *sgt,
 		unsigned long attrs)
 {
 	unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
-	struct vm_struct *area = find_vm_area(cpu_addr);
+	struct page **pages;
 
 	if (!is_vmalloc_addr(cpu_addr)) {
 		struct page *page = virt_to_page(cpu_addr);
@@ -1112,10 +1120,10 @@ static int iommu_dma_get_sgtable(struct device *dev, struct sg_table *sgt,
 		return __iommu_dma_get_sgtable_page(sgt, page, size);
 	}
 
-	if (WARN_ON(!area || !area->pages))
+	pages = __iommu_dma_get_pages(cpu_addr);
+	if (WARN_ON_ONCE(!pages))
 		return -ENXIO;
-
-	return sg_alloc_table_from_pages(sgt, area->pages, count, 0, size,
+	return sg_alloc_table_from_pages(sgt, pages, count, 0, size,
 					 GFP_KERNEL);
 }
 
-- 
2.20.1