Each importer can now provide an invalidate_mappings callback.
This allows the exporter to provide the mappings without the need to pin
the backing store.
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
---
drivers/dma-buf/dma-buf.c | 25 +++++++++++++++++++++++++
include/linux/dma-buf.h | 36 ++++++++++++++++++++++++++++++++++++
2 files changed, 61 insertions(+)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index d78d5fc173dc..ed8d5844ae74 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -629,6 +629,9 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
might_sleep();
+ if (attach->invalidate_mappings)
+ reservation_object_assert_held(attach->dmabuf->resv);
+
if (WARN_ON(!attach || !attach->dmabuf))
return ERR_PTR(-EINVAL);
@@ -656,6 +659,9 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
{
might_sleep();
+ if (attach->invalidate_mappings)
+ reservation_object_assert_held(attach->dmabuf->resv);
+
if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
return;
@@ -664,6 +670,25 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
}
EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
+/**
+ * dma_buf_invalidate_mappings - invalidate all mappings of this dma_buf
+ *
+ * @dmabuf: [in] buffer which mappings should be invalidated
+ *
+ * Informs all attachmenst that they need to destroy and recreated all their
+ * mappings.
+ */
+void dma_buf_invalidate_mappings(struct dma_buf *dmabuf)
+{
+ struct dma_buf_attachment *attach;
+
+ reservation_object_assert_held(dmabuf->resv);
+
+ list_for_each_entry(attach, &dmabuf->attachments, node)
+ attach->invalidate_mappings(attach);
+}
+EXPORT_SYMBOL_GPL(dma_buf_invalidate_mappings);
+
/**
* DOC: cpu access
*
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 085db2fee2d7..c1e2f7d93509 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -91,6 +91,18 @@ struct dma_buf_ops {
*/
void (*detach)(struct dma_buf *, struct dma_buf_attachment *);
+ /**
+ * @supports_mapping_invalidation:
+ *
+ * True for exporters which supports unpinned DMA-buf operation using
+ * the reservation lock.
+ *
+ * When attachment->invalidate_mappings is set the @map_dma_buf and
+ * @unmap_dma_buf callbacks can be called with the reservation lock
+ * held.
+ */
+ bool supports_mapping_invalidation;
+
/**
* @map_dma_buf:
*
@@ -326,6 +338,29 @@ struct dma_buf_attachment {
struct device *dev;
struct list_head node;
void *priv;
+
+ /**
+ * @invalidate_mappings:
+ *
+ * Optional callback provided by the importer of the attachment which
+ * must be set before mappings are created.
+ *
+ * If provided the exporter can avoid pinning the backing store while
+ * mappings exists.
+ *
+ * The function is called with the lock of the reservation object
+ * associated with the dma_buf held and the mapping function must be
+ * called with this lock held as well. This makes sure that no mapping
+ * is created concurrently with an ongoing invalidation.
+ *
+ * After the callback all existing mappings are still valid until all
+ * fences in the dma_bufs reservation object are signaled, but should be
+ * destroyed by the importer as soon as possible.
+ *
+ * New mappings can be created immediately, but can't be used before the
+ * exclusive fence in the dma_bufs reservation object is signaled.
+ */
+ void (*invalidate_mappings)(struct dma_buf_attachment *attach);
};
/**
@@ -391,6 +426,7 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
enum dma_data_direction);
void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
enum dma_data_direction);
+void dma_buf_invalidate_mappings(struct dma_buf *dma_buf);
int dma_buf_begin_cpu_access(struct dma_buf *dma_buf,
enum dma_data_direction dir);
int dma_buf_end_cpu_access(struct dma_buf *dma_buf,
--
2.14.1
