Allow dma_map_sgtable() to pass errors from the map_sg() ops. This will be required for returning appropriate error codes when mapping P2PDMA memory.
Introduce __dma_map_sg_attrs() which will return the raw error code from the map_sg operation (whether it be negative or zero). Then add a dma_map_sg_attrs() wrapper to convert any negative errors to zero to satisfy the existing calling convention. dma_map_sgtable() will convert a zero error return for old map_sg() ops into a -EINVAL return and return any negative errors as reported. This allows map_sg implementations to start returning multiple negative error codes. Legacy map_sg implementations can continue to return zero until they are all converted. Signed-off-by: Logan Gunthorpe <[email protected]> --- include/linux/dma-map-ops.h | 8 ++++++-- include/linux/dma-mapping.h | 41 ++++++++++++++++++++++++++++++++----- kernel/dma/mapping.c | 13 +++++------- 3 files changed, 47 insertions(+), 15 deletions(-) diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h index 0d53a96a3d64..eaa969be8284 100644 --- a/include/linux/dma-map-ops.h +++ b/include/linux/dma-map-ops.h @@ -41,8 +41,12 @@ struct dma_map_ops { size_t size, enum dma_data_direction dir, unsigned long attrs); /* - * map_sg returns 0 on error and a value > 0 on success. - * It should never return a value < 0. + * map_sg should return a negative error code on error. + * dma_map_sgtable() will return the error code returned and convert + * a zero return (for legacy implementations) into -EINVAL. + * + * dma_map_sg() will always return zero on any negative or zero + * return to satisfy its own calling convention. */ int (*map_sg)(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction dir, unsigned long attrs); diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 183e7103a66d..2b0ecf0aa4df 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -105,7 +105,7 @@ dma_addr_t dma_map_page_attrs(struct device *dev, struct page *page, unsigned long attrs); void dma_unmap_page_attrs(struct device *dev, dma_addr_t addr, size_t size, enum dma_data_direction dir, unsigned long attrs); -int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, int nents, +int __dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction dir, unsigned long attrs); void dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction dir, @@ -164,7 +164,7 @@ static inline void dma_unmap_page_attrs(struct device *dev, dma_addr_t addr, size_t size, enum dma_data_direction dir, unsigned long attrs) { } -static inline int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, +static inline int __dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction dir, unsigned long attrs) { return 0; @@ -343,6 +343,34 @@ static inline void dma_sync_single_range_for_device(struct device *dev, return dma_sync_single_for_device(dev, addr + offset, size, dir); } +/** + * dma_map_sg_attrs - Map the given buffer for DMA + * @dev: The device for which to perform the DMA operation + * @sg: The sg_table object describing the buffer + * @dir: DMA direction + * @attrs: Optional DMA attributes for the map operation + * + * Maps a buffer described by a scatterlist passed in the sg argument with + * nents segments for the @dir DMA operation by the @dev device. + * + * Returns the number of mapped entries (which can be less than nents) + * on success. Zero is returned for any error. + * + * dma_unmap_sg_attrs() should be used to unmap the buffer with the + * original sg and original nents (not the value returned by this funciton). + */ +static inline int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, + int nents, enum dma_data_direction dir, unsigned long attrs) +{ + int ret; + + ret = __dma_map_sg_attrs(dev, sg, nents, dir, attrs); + if (ret < 0) + ret = 0; + + return ret; +} + /** * dma_map_sgtable - Map the given buffer for DMA * @dev: The device for which to perform the DMA operation @@ -357,16 +385,19 @@ static inline void dma_sync_single_range_for_device(struct device *dev, * ownership of the buffer back to the CPU domain before touching the * buffer by the CPU. * - * Returns 0 on success or -EINVAL on error during mapping the buffer. + * Returns 0 on success or a negative error code on error */ static inline int dma_map_sgtable(struct device *dev, struct sg_table *sgt, enum dma_data_direction dir, unsigned long attrs) { int nents; - nents = dma_map_sg_attrs(dev, sgt->sgl, sgt->orig_nents, dir, attrs); - if (nents <= 0) + nents = __dma_map_sg_attrs(dev, sgt->sgl, sgt->orig_nents, dir, attrs); + if (nents == 0) return -EINVAL; + else if (nents < 0) + return nents; + sgt->nents = nents; return 0; } diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 2b06a809d0b9..700a2bb7cc9e 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -177,11 +177,7 @@ void dma_unmap_page_attrs(struct device *dev, dma_addr_t addr, size_t size, } EXPORT_SYMBOL(dma_unmap_page_attrs); -/* - * dma_maps_sg_attrs returns 0 on error and > 0 on success. - * It should never return a value < 0. - */ -int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, int nents, +int __dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction dir, unsigned long attrs) { const struct dma_map_ops *ops = get_dma_ops(dev); @@ -197,12 +193,13 @@ int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, int nents, ents = dma_direct_map_sg(dev, sg, nents, dir, attrs); else ents = ops->map_sg(dev, sg, nents, dir, attrs); - BUG_ON(ents < 0); - debug_dma_map_sg(dev, sg, nents, ents, dir); + + if (ents > 0) + debug_dma_map_sg(dev, sg, nents, ents, dir); return ents; } -EXPORT_SYMBOL(dma_map_sg_attrs); +EXPORT_SYMBOL(__dma_map_sg_attrs); void dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction dir, -- 2.20.1 _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
