The Documentation/DMA-API-HOWTO.txt states that dma_map_sg returns the
numer of the created entries in the DMA address space. However the
subsequent calls to dma_sync_sg_for_{device,cpu} and dma_unmap_sg must be
called with the original number of the entries passed to dma_map_sg. The
sg_table->nents in turn holds the result of the dma_map_sg call as stated
in include/linux/scatterlist.h. A common mistake was to ignore a result
of the dma_map_sg function and don't use the sg_table->orig_nents at all.
To avoid such issues, lets use common dma-mapping wrappers operating
directly on the struct sg_table objects and adjust references to the
nents and orig_nents respectively.
Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
---
For more information, see '[PATCH v3 00/25] DRM: fix struct sg_table nents
vs. orig_nents misuse' thread: https://lkml.org/lkml/2020/5/5/187
---
drivers/misc/fastrpc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index e3e085e..0a3e02aa 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -518,7 +518,7 @@ static struct fastrpc_invoke_ctx *fastrpc_context_alloc(
table = &a->sgt;
- if (!dma_map_sg(attachment->dev, table->sgl, table->nents, dir))
+ if (!dma_map_sgtable(attachment->dev, table, dir))
return ERR_PTR(-ENOMEM);
return table;
@@ -528,7 +528,7 @@ static void fastrpc_unmap_dma_buf(struct dma_buf_attachment *attach,
struct sg_table *table,
enum dma_data_direction dir)
{
- dma_unmap_sg(attach->dev, table->sgl, table->nents, dir);
+ dma_unmap_sgtable(attach->dev, table, dir);
}
static void fastrpc_release(struct dma_buf *dmabuf)
--
1.9.1
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