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Message-Id: <20210715164544.6827-2-logang@deltatee.com>
Date: Thu, 15 Jul 2021 10:45:29 -0600
From: Logan Gunthorpe <logang@...tatee.com>
To: linux-kernel@...r.kernel.org, linux-alpha@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-ia64@...r.kernel.org,
linux-mips@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-s390@...r.kernel.org, sparclinux@...r.kernel.org,
iommu@...ts.linux-foundation.org, linux-parisc@...r.kernel.org,
xen-devel@...ts.xenproject.org
Cc: Christoph Hellwig <hch@....de>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Robin Murphy <robin.murphy@....com>,
Stephen Bates <sbates@...thlin.com>,
Martin Oliveira <martin.oliveira@...eticom.com>,
Logan Gunthorpe <logang@...tatee.com>
Subject: [PATCH v1 01/16] 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() 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 <logang@...tatee.com>
---
include/linux/dma-map-ops.h | 8 +++-
include/linux/dma-mapping.h | 35 ++++--------------
kernel/dma/mapping.c | 73 +++++++++++++++++++++++++++++++++----
3 files changed, 78 insertions(+), 38 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..daa1e360f0ee 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -110,6 +110,8 @@ int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, int nents,
void dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg,
int nents, enum dma_data_direction dir,
unsigned long attrs);
+int dma_map_sgtable(struct device *dev, struct sg_table *sgt,
+ enum dma_data_direction dir, unsigned long attrs);
dma_addr_t dma_map_resource(struct device *dev, phys_addr_t phys_addr,
size_t size, enum dma_data_direction dir, unsigned long attrs);
void dma_unmap_resource(struct device *dev, dma_addr_t addr, size_t size,
@@ -174,6 +176,11 @@ static inline void dma_unmap_sg_attrs(struct device *dev,
unsigned long attrs)
{
}
+static inline int dma_map_sgtable(struct device *dev, struct sg_table *sgt,
+ enum dma_data_direction dir, unsigned long attrs)
+{
+ return -EOPNOTSUPP;
+}
static inline dma_addr_t dma_map_resource(struct device *dev,
phys_addr_t phys_addr, size_t size, enum dma_data_direction dir,
unsigned long attrs)
@@ -343,34 +350,6 @@ 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_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 -EINVAL on error during mapping the buffer.
- */
-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)
- return -EINVAL;
- sgt->nents = nents;
- return 0;
-}
-
/**
* dma_unmap_sgtable - Unmap the given buffer for DMA
* @dev: The device for which to perform the DMA operation
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 2b06a809d0b9..30f89d244566 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 +193,74 @@ 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;
}
+
+/**
+ * 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)
+ ret = 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
+ */
+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 -EINVAL;
+ else if (nents < 0)
+ return nents;
+
+ sgt->nents = nents;
+ return 0;
+}
+EXPORT_SYMBOL(dma_map_sgtable);
+
void dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg,
int nents, enum dma_data_direction dir,
unsigned long attrs)
--
2.20.1
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