Patch "arm64: dma-mapping: Fix dma_mapping_error() when bypassing SWIOTLB" has been added to the 4.10-stable tree

This is a note to let you know that I've just added the patch titled

arm64: dma-mapping: Fix dma_mapping_error() when bypassing SWIOTLB

to the 4.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
arm64-dma-mapping-fix-dma_mapping_error-when-bypassing-swiotlb.patch
and it can be found in the queue-4.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Robin Murphy <[email protected]>
Date: Wed, 25 Jan 2017 18:31:31 +0000
Subject: arm64: dma-mapping: Fix dma_mapping_error() when bypassing SWIOTLB

From: Robin Murphy <[email protected]>

commit adbe7e26f4257f72817495b9bce114284060b0d7 upstream.

When bypassing SWIOTLB on small-memory systems, we need to avoid calling into swiotlb_dma_mapping_error() in exactly the same way as we avoid swiotlb_dma_supported(), because the former also relies on SWIOTLB state being initialised.

Under the assumptions for which we skip SWIOTLB, dma_map_{single,page}() will only ever return the DMA-offset-adjusted physical address of the page passed in, thus we can report success unconditionally.

---
 arch/arm64/mm/dma-mapping.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

@@ -352,6 +352,13 @@ static int __swiotlb_dma_supported(struc
 	return 1;
 }
 
+static int __swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t addr)
+{
+	if (swiotlb)
+		return swiotlb_dma_mapping_error(hwdev, addr);
+	return 0;
+}
+
 static struct dma_map_ops swiotlb_dma_ops = {
 	.alloc = __dma_alloc,
 	.free = __dma_free,

@@ -366,7 +373,7 @@ static struct dma_map_ops swiotlb_dma_op
 	.sync_sg_for_cpu = __swiotlb_sync_sg_for_cpu,
 	.sync_sg_for_device = __swiotlb_sync_sg_for_device,
 	.dma_supported = __swiotlb_dma_supported,
-	.mapping_error = swiotlb_dma_mapping_error,
+	.mapping_error = __swiotlb_dma_mapping_error,
 };
 
 static int __init atomic_pool_init(void)

Patches currently in stable-queue which might be from [email protected] are

queue-4.10/arm64-dma-mapping-fix-dma_mapping_error-when-bypassing-swiotlb.patch