Am 18.06.2018 um 10:22 schrieb Daniel Vetter:
On Fri, Jun 01, 2018 at 02:00:18PM +0200, Christian König wrote:
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.
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
Agreed in principle, but I expect a fireworks show with just this patch
applied. It's not just that we need to audit all the implementations of
dma-buf-ops, we also need to audit all the callers.
Ah, yeah of course a good point.
No idea yet how to go about merging this, but for a start might be good to
throw this at the intel-gfx CI (just Cc: the intel-gfx mailing lists, but
make sure your series applies without amd-staging-next stuff which isn't
in drm.git yet).
Ok, going to incorporate all your other comments as well and then send
the next round of this with CCing intel-gfx as well.
Thanks for the review,
Christian.
-Daniel
---
drivers/dma-buf/dma-buf.c | 4 ++++
include/linux/dma-buf.h | 4 ++++
2 files changed, 8 insertions(+)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index e4c657d9fad7..4f0708cb58a7 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -631,7 +631,9 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
if (WARN_ON(!attach || !attach->dmabuf))
return ERR_PTR(-EINVAL);
+ reservation_object_lock(attach->dmabuf->resv, NULL);
sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
+ reservation_object_unlock(attach->dmabuf->resv);
if (!sg_table)
sg_table = ERR_PTR(-ENOMEM);
@@ -658,8 +660,10 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
return;
+ reservation_object_lock(attach->dmabuf->resv, NULL);
attach->dmabuf->ops->unmap_dma_buf(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 d17cadd76802..d2ba7a027a78 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -118,6 +118,8 @@ struct dma_buf_ops {
* any other kind of sharing that the exporter might wish to make
* available to buffer-users.
*
+ * This is called with the dmabuf->resv object locked.
+ *
* Returns:
*
* A &sg_table scatter list of or the backing storage of the DMA buffer,
@@ -138,6 +140,8 @@ 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 called with the dmabuf->resv object locked.
*/
void (*unmap_dma_buf)(struct dma_buf_attachment *,
struct sg_table *,
--
2.14.1
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