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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>
This commit is contained in:
Christoph Hellwig 2018-11-21 18:52:35 +01:00
parent a1da439cc0
commit 42ee3cae0e
1 changed files with 5 additions and 0 deletions
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5
include/linux/dma-mapping.h
View File

@ -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;
}