From 42ee3cae0ed38b6c04038bf851ea2496da2135bb Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 21 Nov 2018 18:52:35 +0100 Subject: [PATCH] dma-mapping: provide a generic DMA_MAPPING_ERROR Error handling of the dma_map_single and dma_map_page APIs is a little problematic at the moment, in that we use different encodings in the returned dma_addr_t to indicate an error. That means we require an additional indirect call to figure out if a dma mapping call returned an error, and a lot of boilerplate code to implement these semantics. Instead return the maximum addressable value as the error. As long as we don't allow mapping single-byte ranges with single-byte alignment this value can never be a valid return. Additionaly if drivers do not check the return value from the dma_map* routines this values means they will generally not be pointed to actual memory. Once the default value is added here we can start removing the various mapping_error methods and just rely on this generic check. Signed-off-by: Christoph Hellwig Reviewed-by: Robin Murphy Acked-by: Russell King Acked-by: Linus Torvalds --- include/linux/dma-mapping.h | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 1a0edcde7d14..f89d277cc8ed 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -133,6 +133,8 @@ struct dma_map_ops { u64 (*get_required_mask)(struct device *dev); }; +#define DMA_MAPPING_ERROR (~(dma_addr_t)0) + extern const struct dma_map_ops dma_direct_ops; extern const struct dma_map_ops dma_virt_ops; @@ -581,8 +583,11 @@ static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr) const struct dma_map_ops *ops = get_dma_ops(dev); debug_dma_mapping_error(dev, dma_addr); + if (ops->mapping_error) return ops->mapping_error(dev, dma_addr); + if (dma_addr == DMA_MAPPING_ERROR) + return 1; return 0; } -- GitLab