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 <hch@lst.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Russell King <rmk+kernel@armlinux.org.uk>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 1a0edcd..f89d277 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -133,6 +133,8 @@
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 @@
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;
}