[PATCH 11/23] iommu/dma: Refactor iommu_dma_free

Christoph Hellwig
2019-05-23T07:01:11Z

From: Robin Murphy <robin.murphy@arm.com>

The freeing logic was made particularly horrible by part of it being
opaque to the arch wrapper, which led to a lot of convoluted repetition
to ensure each path did everything in the right order. Now that it's
all private, we can pick apart and consolidate the logically-distinct
steps of freeing the IOMMU mapping, the underlying pages, and the CPU
remap (if necessary) into something much more manageable.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
[various cosmetic changes to the code flow]
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/iommu/dma-iommu.c | 73 ++++++++++++++++++---------------------
1 file changed, 33 insertions(+), 40 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 191c0a4c8e31..f61e3f8861a8 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -935,6 +935,39 @@ static void iommu_dma_unmap_resource(struct device *dev, dma_addr_t handle,
__iommu_dma_unmap(dev, handle, size);
}

+static void iommu_dma_free(struct device *dev, size_t size, void *cpu_addr,
+ dma_addr_t handle, unsigned long attrs)
+{
+ size_t alloc_size = PAGE_ALIGN(size);
+ int count = alloc_size >> PAGE_SHIFT;
+ struct page *page = NULL, **pages = NULL;
+
+ __iommu_dma_unmap(dev, handle, size);
+
+ /* Non-coherent atomic allocation? Easy */
+ if (dma_free_from_pool(cpu_addr, alloc_size))
+ return;
+
+ if (is_vmalloc_addr(cpu_addr)) {
+ /*
+ * If it the address is remapped, then it's either non-coherent
+ * or highmem CMA, or an iommu_dma_alloc_remap() construction.
+ */
+ pages = __iommu_dma_get_pages(cpu_addr);
+ if (!pages)
+ page = vmalloc_to_page(cpu_addr);
+ dma_common_free_remap(cpu_addr, alloc_size, VM_USERMAP);
+ } else {
+ /* Lowmem means a coherent atomic or CMA allocation */
+ page = virt_to_page(cpu_addr);
+ }
+
+ if (pages)
+ __iommu_dma_free_pages(pages, count);
+ if (page && !dma_release_from_contiguous(dev, page, count))
+ __free_pages(page, get_order(alloc_size));
+}
+
static void *iommu_dma_alloc(struct device *dev, size_t size,
dma_addr_t *handle, gfp_t gfp, unsigned long attrs)
{
@@ -1004,46 +1037,6 @@ static void *iommu_dma_alloc(struct device *dev, size_t size,
return addr;
}

-static void iommu_dma_free(struct device *dev, size_t size, void *cpu_addr,
- dma_addr_t handle, unsigned long attrs)
-{
- size_t iosize = size;
-
- size = PAGE_ALIGN(size);
- /*
- * @cpu_addr will be one of 4 things depending on how it was allocated:
- * - A remapped array of pages for contiguous allocations.
- * - A remapped array of pages from iommu_dma_alloc_remap(), for all
- * non-atomic allocations.
- * - A non-cacheable alias from the atomic pool, for atomic
- * allocations by non-coherent devices.
- * - A normal lowmem address, for atomic allocations by
- * coherent devices.
- * Hence how dodgy the below logic looks...
- */
- if (dma_in_atomic_pool(cpu_addr, size)) {
- __iommu_dma_unmap(dev, handle, iosize);
- dma_free_from_pool(cpu_addr, size);
- } else if (attrs & DMA_ATTR_FORCE_CONTIGUOUS) {
- struct page *page = vmalloc_to_page(cpu_addr);
-
- __iommu_dma_unmap(dev, handle, iosize);
- 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 page **pages = __iommu_dma_get_pages(cpu_addr);
-
- if (!pages)
- return;
- __iommu_dma_unmap(dev, handle, iosize);
- __iommu_dma_free_pages(pages, size >> PAGE_SHIFT);
- dma_common_free_remap(cpu_addr, size, VM_USERMAP);
- } else {
- __iommu_dma_unmap(dev, handle, iosize);
- __free_pages(virt_to_page(cpu_addr), get_order(size));
- }
-}
-
static int __iommu_dma_mmap_pfn(struct vm_area_struct *vma,
unsigned long pfn, size_t size)
{
--
2.20.1