[PATCH RFC 04/26] dma-buf: Route SGT related actions through attach->map_type

Jason Gunthorpe
2026-02-18T00:12:19Z

Now that dma_buf_mapping_attach() ensures a mapping_type exists, even for
exporters and importers that don't provide it, route operations through the
map_type.

For map/unmap this will go through dma_buf_sgt_compat_map_dma_buf() which
calls the same attach->dmabuf->ops->map_dma_buf().

Move the debugfs processing unique to SGT into a callback too.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
drivers/dma-buf/dma-buf.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 6e89fcfdad3015..4211ae2b462bdd 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -1149,12 +1149,14 @@ EXPORT_SYMBOL_NS_GPL(dma_buf_unpin, "DMA_BUF");
struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
enum dma_data_direction direction)
{
+ const struct dma_buf_mapping_sgt_exp_ops *sgt_exp_ops =
+ dma_buf_get_sgt_ops(attach);
struct sg_table *sg_table;
signed long ret;

might_sleep();

- if (WARN_ON(!attach || !attach->dmabuf))
+ if (WARN_ON(!attach || !attach->dmabuf || !sgt_exp_ops))
return ERR_PTR(-EINVAL);

dma_resv_assert_held(attach->dmabuf->resv);
@@ -1170,7 +1172,7 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
return ERR_PTR(ret);
}

- sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
+ sg_table = sgt_exp_ops->map_dma_buf(attach, direction);
if (!sg_table)
sg_table = ERR_PTR(-ENOMEM);
if (IS_ERR(sg_table))
@@ -1208,7 +1210,7 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
return sg_table;

error_unmap:
- attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction);
+ sgt_exp_ops->unmap_dma_buf(attach, sg_table, direction);
sg_table = ERR_PTR(ret);

error_unpin:
@@ -1261,15 +1263,18 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
struct sg_table *sg_table,
enum dma_data_direction direction)
{
+ const struct dma_buf_mapping_sgt_exp_ops *sgt_exp_ops =
+ dma_buf_get_sgt_ops(attach);
+
might_sleep();

- if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
+ if (WARN_ON(!attach || !attach->dmabuf || !sg_table || !sgt_exp_ops))
return;

dma_resv_assert_held(attach->dmabuf->resv);

mangle_sg_table(sg_table);
- attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction);
+ sgt_exp_ops->unmap_dma_buf(attach, sg_table, direction);

if (dma_buf_pin_on_map(attach))
attach->dmabuf->ops->unpin(attach);
@@ -1700,7 +1705,11 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
attach_count = 0;

list_for_each_entry(attach_obj, &buf_obj->attachments, node) {
- seq_printf(s, "\t%s\n", dev_name(attach_obj->dev));
+ seq_printf(s, "\t%s:", attach_obj->map_type.type->name);
+ if (attach_obj->map_type.type->debugfs_dump)
+ attach_obj->map_type.type->debugfs_dump(
+ s, attach_obj);
+ seq_putc(s, '\n');
attach_count++;
}
dma_resv_unlock(buf_obj->resv);
--
2.43.0