If a syncobj has not yet been assigned, treat it as a future fence and
install and wait upon a dma-fence-proxy. The proxy will be replace by
the real fence later, and that fence will be responsible for signaling
our waiter.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
.../gpu/drm/i915/gem/i915_gem_execbuffer.c | 21 +++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index d3f4f28e9468..bbe501a3e619 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -5,6 +5,7 @@
*/
#include <linux/intel-iommu.h>
+#include <linux/dma-fence-proxy.h>
#include <linux/dma-resv.h>
#include <linux/sync_file.h>
#include <linux/uaccess.h>
@@ -2260,8 +2261,24 @@ await_fence_array(struct i915_execbuffer *eb,
continue;
fence = drm_syncobj_fence_get(syncobj);
- if (!fence)
- return -EINVAL;
+ if (!fence) {
+ struct dma_fence *old;
+
+ fence = dma_fence_create_proxy();
+ if (!fence)
+ return -ENOMEM;
+
+ spin_lock(&syncobj->lock);
+ old = rcu_dereference_protected(syncobj->fence, true);
+ if (unlikely(old)) {
+ dma_fence_put(fence);
+ fence = dma_fence_get(old);
+ } else {
+ rcu_assign_pointer(syncobj->fence,
+ dma_fence_get(fence));
+ }
+ spin_unlock(&syncobj->lock);
+ }
err = i915_request_await_dma_fence(eb->request, fence);
dma_fence_put(fence);
--
2.20.1
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