[PATCH 17/23] iommu/dma: Refactor iommu_dma_alloc, part 2

Christoph Hellwig
2019-05-23T07:01:28Z

All the logic in iommu_dma_alloc that deals with page allocation from
the CMA or page allocators can be split into a self-contained helper,
and we can than map the result of that or the atomic pool allocation
with the iommu later. This also allows reusing __iommu_dma_free to
tear down the allocations and MMU mappings when the IOMMU mapping
fails.

Based on a patch from Robin Murphy.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/iommu/dma-iommu.c | 65 +++++++++++++++++++++------------------
1 file changed, 35 insertions(+), 30 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 9ac76d286df1..9f0aa80f2bdd 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -972,35 +972,14 @@ static void iommu_dma_free(struct device *dev, size_t size, void *cpu_addr,
__iommu_dma_free(dev, size, cpu_addr);
}

-static void *iommu_dma_alloc(struct device *dev, size_t size,
- dma_addr_t *handle, gfp_t gfp, unsigned long attrs)
+static void *iommu_dma_alloc_pages(struct device *dev, size_t size,
+ struct page **pagep, gfp_t gfp, unsigned long attrs)
{
bool coherent = dev_is_dma_coherent(dev);
- int ioprot = dma_info_to_prot(DMA_BIDIRECTIONAL, coherent, attrs);
size_t alloc_size = PAGE_ALIGN(size);
struct page *page = NULL;
void *cpu_addr;

- gfp |= __GFP_ZERO;
-
- if (gfpflags_allow_blocking(gfp) &&
- !(attrs & DMA_ATTR_FORCE_CONTIGUOUS))
- return iommu_dma_alloc_remap(dev, size, handle, gfp, attrs);
-
- if (!gfpflags_allow_blocking(gfp) && !coherent) {
- cpu_addr = dma_alloc_from_pool(alloc_size, &page, gfp);
- if (!cpu_addr)
- return NULL;
-
- *handle = __iommu_dma_map(dev, page_to_phys(page), size,
- ioprot);
- if (*handle == DMA_MAPPING_ERROR) {
- dma_free_from_pool(cpu_addr, alloc_size);
- return NULL;
- }
- return cpu_addr;
- }
-
if (gfpflags_allow_blocking(gfp))
page = dma_alloc_from_contiguous(dev, alloc_size >> PAGE_SHIFT,
get_order(alloc_size),
@@ -1010,33 +989,59 @@ static void *iommu_dma_alloc(struct device *dev, size_t size,
if (!page)
return NULL;

- *handle = __iommu_dma_map(dev, page_to_phys(page), size, ioprot);
- if (*handle == DMA_MAPPING_ERROR)
- goto out_free_pages;
-
if (!coherent || PageHighMem(page)) {
pgprot_t prot = arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs);

cpu_addr = dma_common_contiguous_remap(page, alloc_size,
VM_USERMAP, prot, __builtin_return_address(0));
if (!cpu_addr)
- goto out_unmap;
+ goto out_free_pages;

if (!coherent)
arch_dma_prep_coherent(page, size);
} else {
cpu_addr = page_address(page);
}
+
+ *pagep = page;
memset(cpu_addr, 0, alloc_size);
return cpu_addr;
-out_unmap:
- __iommu_dma_unmap(dev, *handle, size);
out_free_pages:
if (!dma_release_from_contiguous(dev, page, alloc_size >> PAGE_SHIFT))
__free_pages(page, get_order(alloc_size));
return NULL;
}

+static void *iommu_dma_alloc(struct device *dev, size_t size,
+ dma_addr_t *handle, gfp_t gfp, unsigned long attrs)
+{
+ bool coherent = dev_is_dma_coherent(dev);
+ int ioprot = dma_info_to_prot(DMA_BIDIRECTIONAL, coherent, attrs);
+ struct page *page = NULL;
+ void *cpu_addr;
+
+ gfp |= __GFP_ZERO;
+
+ if (gfpflags_allow_blocking(gfp) &&
+ !(attrs & DMA_ATTR_FORCE_CONTIGUOUS))
+ return iommu_dma_alloc_remap(dev, size, handle, gfp, attrs);
+
+ if (!gfpflags_allow_blocking(gfp) && !coherent)
+ cpu_addr = dma_alloc_from_pool(PAGE_ALIGN(size), &page, gfp);
+ else
+ cpu_addr = iommu_dma_alloc_pages(dev, size, &page, gfp, attrs);
+ if (!cpu_addr)
+ return NULL;
+
+ *handle = __iommu_dma_map(dev, page_to_phys(page), size, ioprot);
+ if (*handle == DMA_MAPPING_ERROR) {
+ __iommu_dma_free(dev, size, cpu_addr);
+ return NULL;
+ }
+
+ return cpu_addr;
+}
+
static int __iommu_dma_mmap_pfn(struct vm_area_struct *vma,
unsigned long pfn, size_t size)
{
--
2.20.1