iommu/vt-d: remove the mapping_error dma_map_ops method

Return DMA_MAPPING_ERROR instead of 0 on a dma mapping failure and let
the core dma-mapping code handle the rest.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/iommu/intel-iommu.c

@@ -3617,7 +3617,7 @@ static dma_addr_t __intel_map_page(struct device *dev, struct page *page,
 
 	domain = get_valid_domain_for_dev(dev);
 	if (!domain)
-		return 0;
+		return DMA_MAPPING_ERROR;
 
 	iommu = domain_get_iommu(domain);
 	size = aligned_nrpages(paddr, size);
@@ -3655,7 +3655,7 @@ static dma_addr_t __intel_map_page(struct device *dev, struct page *page,
 		free_iova_fast(&domain->iovad, iova_pfn, dma_to_mm_pfn(size));
 	pr_err("Device %s request: %zx@%llx dir %d --- failed\n",
 		dev_name(dev), size, (unsigned long long)paddr, dir);
-	return 0;
+	return DMA_MAPPING_ERROR;
 }
 
 static dma_addr_t intel_map_page(struct device *dev, struct page *page,
@@ -3756,7 +3756,7 @@ static void *intel_alloc_coherent(struct device *dev, size_t size,
 
 	*dma_handle = __intel_map_page(dev, page, 0, size, DMA_BIDIRECTIONAL,
 				       dev->coherent_dma_mask);
-	if (*dma_handle)
+	if (*dma_handle != DMA_MAPPING_ERROR)
 		return page_address(page);
 	if (!dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT))
 		__free_pages(page, order);
@@ -3865,11 +3865,6 @@ static int intel_map_sg(struct device *dev, struct scatterlist *sglist, int nele
 	return nelems;
 }
 
-static int intel_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return !dma_addr;
-}
-
 static const struct dma_map_ops intel_dma_ops = {
 	.alloc = intel_alloc_coherent,
 	.free = intel_free_coherent,
@@ -3877,7 +3872,6 @@ static const struct dma_map_ops intel_dma_ops = {
 	.unmap_sg = intel_unmap_sg,
 	.map_page = intel_map_page,
 	.unmap_page = intel_unmap_page,
-	.mapping_error = intel_mapping_error,
 	.dma_supported = dma_direct_supported,
 };