[PATCH] iommu/arm-smmu: fix leak in arm_smmu_flush_pgtable

[Mitchel Humpherys]

We're currently mapping a page in arm_smmu_flush_pgtable without ever
unmapping it.  Fix this by calling dma_unmap_page on the returned dma
address.  Since the only reason we're calling dma_map_page is to make
sure it actually gets flushed out to RAM, we can just call
dma_unmap_page immediately following the map.

Without this, eventually swiotlb runs out of memory and starts printing
things like:

    [   35.545076] arm-smmu d00000.arm,smmu: swiotlb buffer is full (sz: 128 bytes)

Signed-off-by: Mitchel Humpherys <mitchelh at codeaurora.org>
---
 drivers/iommu/arm-smmu.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index fc13dd56953e..2ff8f35cf533 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -627,8 +627,13 @@ static void arm_smmu_flush_pgtable(void *addr, size_t size, void *cookie)
 		 * recursion here as the SMMU table walker will not be wired
 		 * through another SMMU.
 		 */
-		dma_map_page(smmu->dev, virt_to_page(addr), offset, size,
-			     DMA_TO_DEVICE);
+		dma_addr_t handle = dma_map_page(smmu->dev, virt_to_page(addr),
+						offset, size, DMA_TO_DEVICE);
+		if (handle == DMA_ERROR_CODE)
+			dev_err(smmu->dev,
+				"Couldn't flush page tables at %p!\n", addr);
+		else
+			dma_unmap_page(smmu->dev, handle, size, DMA_TO_DEVICE);
 	}
 }
 
-- 
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