[PATCH 2/6] drm/syncobj: Allow use of dma-fence-proxy

[Chris Wilson]

Allow the callers to supply a dma-fence-proxy for asynchronous waiting on
future fences.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/drm_syncobj.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index 42d46414f767..e6efd85f8d8f 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -184,6 +184,7 @@
  */
 
 #include <linux/anon_inodes.h>
+#include <linux/dma-fence-proxy.h>
 #include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/sched/signal.h>
@@ -311,6 +312,11 @@ void drm_syncobj_add_point(struct drm_syncobj *syncobj,
 }
 EXPORT_SYMBOL(drm_syncobj_add_point);
 
+static struct dma_fence **get_fence_slot(struct drm_syncobj *syncobj)
+{
+	return (struct dma_fence __force **)syncobj->fence;
+}
+
 /**
  * drm_syncobj_replace_fence - replace fence in a sync object.
  * @syncobj: Sync object to replace fence in
@@ -329,9 +335,7 @@ void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
 
 	spin_lock(&syncobj->lock);
 
-	old_fence = rcu_dereference_protected(syncobj->fence,
-					      lockdep_is_held(&syncobj->lock));
-	rcu_assign_pointer(syncobj->fence, fence);
+	old_fence = dma_fence_replace_proxy(get_fence_slot(syncobj), fence);
 
 	if (fence != old_fence) {
 		list_for_each_entry_safe(cur, tmp, &syncobj->cb_list, node)
-- 
2.25.1