From fffe3cc8c2194f60c4af4fac7f27d25e8828f001 Mon Sep 17 00:00:00 2001 From: Logan Gunthorpe Date: Thu, 29 Jul 2021 14:15:19 -0600 Subject: dma-mapping: allow map_sg() ops to return negative error codes 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() defines three error codes that .map_sg implementations are allowed to return: -EINVAL, -ENOMEM and -EIO. The latter of which is a generic return for cases that are passing DMA_MAPPING_ERROR through. dma_map_sgtable() will convert a zero error return for old map_sg() ops into a -EIO 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 Signed-off-by: Christoph Hellwig --- kernel/dma/mapping.c | 82 +++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 74 insertions(+), 8 deletions(-) (limited to 'kernel/dma/mapping.c') diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 2b06a809d0b9..21e550076be5 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -177,12 +177,8 @@ 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, - enum dma_data_direction dir, unsigned long attrs) +static 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); int ents; @@ -197,13 +193,83 @@ 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); + else if (WARN_ON_ONCE(ents != -EINVAL && ents != -ENOMEM && + ents != -EIO && ents != 0)) + return -EIO; return ents; } + +/** + * 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). + */ +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) + return 0; + return ret; +} EXPORT_SYMBOL(dma_map_sg_attrs); +/** + * dma_map_sgtable - Map the given buffer for DMA + * @dev: The device for which to perform the DMA operation + * @sgt: 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 stored in the given sg_table + * object for the @dir DMA operation by the @dev device. After success, the + * ownership for the buffer is transferred to the DMA domain. One has to + * call dma_sync_sgtable_for_cpu() or dma_unmap_sgtable() to move the + * ownership of the buffer back to the CPU domain before touching the + * buffer by the CPU. + * + * Returns 0 on success or a negative error code on error. The following + * error codes are supported with the given meaning: + * + * -EINVAL - An invalid argument, unaligned access or other error + * in usage. Will not succeed if retried. + * -ENOMEM - Insufficient resources (like memory or IOVA space) to + * complete the mapping. Should succeed if retried later. + * -EIO - Legacy error code with an unknown meaning. eg. this is + * returned if a lower level call returned DMA_MAPPING_ERROR. + */ +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) + return -EIO; + if (nents < 0) + return nents; + sgt->nents = nents; + return 0; +} +EXPORT_SYMBOL_GPL(dma_map_sgtable); + void dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction dir, unsigned long attrs) -- cgit v1.2.3 From d03c54419274f96434e2ad74e59e67ec6d54ca86 Mon Sep 17 00:00:00 2001 From: Logan Gunthorpe Date: Mon, 9 Aug 2021 17:13:31 +0200 Subject: dma-mapping: disallow .map_sg operations from returning zero on error Now that all the .map_sg operations have been converted to returning proper error codes, drop the code to handle a zero return value, add a warning if a zero is returned. Signed-off-by: Logan Gunthorpe Signed-off-by: Christoph Hellwig --- kernel/dma/mapping.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'kernel/dma/mapping.c') diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 21e550076be5..967b62692102 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -197,7 +197,7 @@ static int __dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, if (ents > 0) debug_dma_map_sg(dev, sg, nents, ents, dir); else if (WARN_ON_ONCE(ents != -EINVAL && ents != -ENOMEM && - ents != -EIO && ents != 0)) + ents != -EIO)) return -EIO; return ents; @@ -261,8 +261,6 @@ int dma_map_sgtable(struct device *dev, struct sg_table *sgt, int nents; nents = __dma_map_sg_attrs(dev, sgt->sgl, sgt->orig_nents, dir, attrs); - if (nents == 0) - return -EIO; if (nents < 0) return nents; sgt->nents = nents; -- cgit v1.2.3 From 2a047e0662aee1bd773e0415accd785ad26a9398 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 9 Aug 2021 17:19:36 +0200 Subject: dma-mapping: return an unsigned int from dma_map_sg{,_attrs} These can only return 0 for failure or the number of entries, so turn the return value into an unsigned int. Signed-off-by: Christoph Hellwig Reviewed-by: Logan Gunthorpe --- include/linux/dma-mapping.h | 9 +++++---- kernel/dma/mapping.c | 2 +- 2 files changed, 6 insertions(+), 5 deletions(-) (limited to 'kernel/dma/mapping.c') diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index daa1e360f0ee..dca2b1355bb1 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -105,8 +105,8 @@ 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, - enum dma_data_direction dir, unsigned long attrs); +unsigned 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, unsigned long attrs); @@ -166,8 +166,9 @@ 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, - int nents, enum dma_data_direction dir, unsigned long attrs) +static inline unsigned int dma_map_sg_attrs(struct device *dev, + struct scatterlist *sg, int nents, enum dma_data_direction dir, + unsigned long attrs) { return 0; } diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 967b62692102..7ee5284bff58 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -219,7 +219,7 @@ static int __dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, * 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). */ -int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, +unsigned int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction dir, unsigned long attrs) { int ret; -- cgit v1.2.3