First step towards unpinned DMA buf operation.
I've checked the DRM drivers to potential locking of the reservation
object, but essentially we need to audit all implementations of the
dma_buf _ops for this to work.
v2: reordered
v3: rebased on sgt caching
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
---
drivers/dma-buf/dma-buf.c | 15 ++++++---------
include/linux/dma-buf.h | 6 ++++++
2 files changed, 12 insertions(+), 9 deletions(-)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index e68322c953a9..21608306349d 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -686,10 +686,9 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
if (WARN_ON(!attach || !attach->dmabuf))
return ERR_PTR(-EINVAL);
- if (attach->sgt)
- return attach->sgt;
-
- sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
+ reservation_object_lock(attach->dmabuf->resv, NULL);
+ sg_table = dma_buf_map_attachment_locked(attach, direction);
+ reservation_object_unlock(attach->dmabuf->resv);
if (!sg_table)
sg_table = ERR_PTR(-ENOMEM);
@@ -742,11 +741,9 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
return;
- if (attach->sgt == sg_table)
- return;
-
- attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
- direction);
+ reservation_object_lock(attach->dmabuf->resv, NULL);
+ dma_buf_unmap_attachment_locked(attach, sg_table, direction);
+ reservation_object_unlock(attach->dmabuf->resv);
}
EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index a40f8f586a95..e964077a7e7e 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -128,6 +128,9 @@ struct dma_buf_ops {
* any other kind of sharing that the exporter might wish to make
* available to buffer-users.
*
+ * This is always called with the dmabuf->resv object locked when
+ * no_sgt_cache is true.
+ *
* Returns:
*
* A &sg_table scatter list of or the backing storage of the DMA buffer,
@@ -148,6 +151,9 @@ struct dma_buf_ops {
* It should also unpin the backing storage if this is the last mapping
* of the DMA buffer, it the exporter supports backing storage
* migration.
+ *
+ * This is always called with the dmabuf->resv object locked when
+ * no_sgt_cache is true.
*/
void (*unmap_dma_buf)(struct dma_buf_attachment *,
struct sg_table *,
--
2.14.1
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