[RFC PATCH 03/12] staging: android: ion: Duplicate sg_table

Laura Abbott
2017-03-02T21:44:35Z

Ion currently returns a single sg_table on each dma_map call. This is
incorrect for later usage.

Signed-off-by: Laura Abbott <labbott@redhat.com>
---
drivers/staging/android/ion/ion.c | 30 +++++++++++++++++++++++++++++-
1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index 94a498e..ce4adac 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -799,6 +799,32 @@ static void ion_buffer_sync_for_device(struct ion_buffer *buffer,
struct device *dev,
enum dma_data_direction direction);

+static struct sg_table *dup_sg_table(struct sg_table *table)
+{
+ struct sg_table *new_table;
+ int ret, i;
+ struct scatterlist *sg, *new_sg;
+
+ new_table = kzalloc(sizeof(*new_table), GFP_KERNEL);
+ if (!new_table)
+ return ERR_PTR(-ENOMEM);
+
+ ret = sg_alloc_table(new_table, table->nents, GFP_KERNEL);
+ if (ret) {
+ kfree(table);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ new_sg = new_table->sgl;
+ for_each_sg(table->sgl, sg, table->nents, i) {
+ memcpy(new_sg, sg, sizeof(*sg));
+ sg->dma_address = 0;
+ new_sg = sg_next(new_sg);
+ }
+
+ return new_table;
+}
+
static struct sg_table *ion_map_dma_buf(struct dma_buf_attachment *attachment,
enum dma_data_direction direction)
{
@@ -806,13 +832,15 @@ static struct sg_table *ion_map_dma_buf(struct dma_buf_attachment *attachment,
struct ion_buffer *buffer = dmabuf->priv;

ion_buffer_sync_for_device(buffer, attachment->dev, direction);
- return buffer->sg_table;
+ return dup_sg_table(buffer->sg_table);
}

static void ion_unmap_dma_buf(struct dma_buf_attachment *attachment,
struct sg_table *table,
enum dma_data_direction direction)
{
+ sg_free_table(table);
+ kfree(table);
}

void ion_pages_sync_for_device(struct device *dev, struct page *page,
--
2.7.4