aboutsummaryrefslogtreecommitdiffstatshomepage
path: root/kernel/dma/mapping.c
diff options
context:
space:
mode:
authorLogan Gunthorpe <logang@deltatee.com>2021-07-29 14:15:19 -0600
committerChristoph Hellwig <hch@lst.de>2021-08-09 17:13:02 +0200
commitfffe3cc8c2194f60c4af4fac7f27d25e8828f001 (patch)
tree355e3659644e50766165690c2d549fd154d684ed /kernel/dma/mapping.c
parentdma-debug: fix debugfs initialization order (diff)
downloadwireguard-linux-fffe3cc8c2194f60c4af4fac7f27d25e8828f001.tar.xz
wireguard-linux-fffe3cc8c2194f60c4af4fac7f27d25e8828f001.zip
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 <logang@deltatee.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'kernel/dma/mapping.c')
-rw-r--r--kernel/dma/mapping.c82
1 files changed, 74 insertions, 8 deletions
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)