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authorMarek Szyprowski <m.szyprowski@samsung.com>2020-04-06 17:41:45 +0300
committerMarek Szyprowski <m.szyprowski@samsung.com>2020-09-10 09:18:35 +0300
commit62296b395a512930686666089ad285b1f78fd2f0 (patch)
tree6284b2edbdc5e508da0c9b1f941b995416466dfe /drivers/dma-buf
parent34e8548168758f1adf50984f40ce190e5c19c621 (diff)
downloadlinux-62296b395a512930686666089ad285b1f78fd2f0.tar.xz
dmabuf: fix common struct sg_table related issues
The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function returns the number of the created entries in the DMA address space. However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and dma_unmap_sg must be called with the original number of the entries passed to the dma_map_sg(). struct sg_table is a common structure used for describing a non-contiguous memory buffer, used commonly in the DRM and graphics subsystems. It consists of a scatterlist with memory pages and DMA addresses (sgl entry), as well as the number of scatterlist entries: CPU pages (orig_nents entry) and DMA mapped pages (nents entry). It turned out that it was a common mistake to misuse nents and orig_nents entries, calling DMA-mapping functions with a wrong number of entries or ignoring the number of mapped entries returned by the dma_map_sg() function. To avoid such issues, lets use a common dma-mapping wrappers operating directly on the struct sg_table objects and use scatterlist page iterators where possible. This, almost always, hides references to the nents and orig_nents entries, making the code robust, easier to follow and copy/paste safe. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Diffstat (limited to 'drivers/dma-buf')
-rw-r--r--drivers/dma-buf/heaps/heap-helpers.c13
-rw-r--r--drivers/dma-buf/udmabuf.c7
2 files changed, 9 insertions, 11 deletions
diff --git a/drivers/dma-buf/heaps/heap-helpers.c b/drivers/dma-buf/heaps/heap-helpers.c
index 9f964ca3f59c..d0696cf937af 100644
--- a/drivers/dma-buf/heaps/heap-helpers.c
+++ b/drivers/dma-buf/heaps/heap-helpers.c
@@ -140,13 +140,12 @@ struct sg_table *dma_heap_map_dma_buf(struct dma_buf_attachment *attachment,
enum dma_data_direction direction)
{
struct dma_heaps_attachment *a = attachment->priv;
- struct sg_table *table;
-
- table = &a->table;
+ struct sg_table *table = &a->table;
+ int ret;
- if (!dma_map_sg(attachment->dev, table->sgl, table->nents,
- direction))
- table = ERR_PTR(-ENOMEM);
+ ret = dma_map_sgtable(attachment->dev, table, direction, 0);
+ if (ret)
+ table = ERR_PTR(ret);
return table;
}
@@ -154,7 +153,7 @@ static void dma_heap_unmap_dma_buf(struct dma_buf_attachment *attachment,
struct sg_table *table,
enum dma_data_direction direction)
{
- dma_unmap_sg(attachment->dev, table->sgl, table->nents, direction);
+ dma_unmap_sgtable(attachment->dev, table, direction, 0);
}
static vm_fault_t dma_heap_vm_fault(struct vm_fault *vmf)
diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
index acb26c627d27..89e293bd9252 100644
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -63,10 +63,9 @@ static struct sg_table *get_sg_table(struct device *dev, struct dma_buf *buf,
GFP_KERNEL);
if (ret < 0)
goto err;
- if (!dma_map_sg(dev, sg->sgl, sg->nents, direction)) {
- ret = -EINVAL;
+ ret = dma_map_sgtable(dev, sg, direction, 0);
+ if (ret < 0)
goto err;
- }
return sg;
err:
@@ -78,7 +77,7 @@ err:
static void put_sg_table(struct device *dev, struct sg_table *sg,
enum dma_data_direction direction)
{
- dma_unmap_sg(dev, sg->sgl, sg->nents, direction);
+ dma_unmap_sgtable(dev, sg, direction, 0);
sg_free_table(sg);
kfree(sg);
}