UPSTREAM: dma-buf: add dma_fence_chain_contained helper am: 005a9bfa

Original change: https://android-review.googlesource.com/c/kernel/common/+/3496924



Change-Id: I721683f3bce7c21a9b04d4109c9b8dbb1415fb2b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

drivers/dma-buf/dma-fence-chain.c

@@ -147,8 +147,7 @@ static bool dma_fence_chain_enable_signaling(struct dma_fence *fence)
 
 	dma_fence_get(&head->base);
 	dma_fence_chain_for_each(fence, &head->base) {
-		struct dma_fence_chain *chain = to_dma_fence_chain(fence);
-		struct dma_fence *f = chain ? chain->fence : fence;
+		struct dma_fence *f = dma_fence_chain_contained(fence);
 
 		dma_fence_get(f);
 		if (!dma_fence_add_callback(f, &head->cb, dma_fence_chain_cb)) {
@@ -164,8 +163,7 @@ static bool dma_fence_chain_enable_signaling(struct dma_fence *fence)
 static bool dma_fence_chain_signaled(struct dma_fence *fence)
 {
 	dma_fence_chain_for_each(fence, fence) {
-		struct dma_fence_chain *chain = to_dma_fence_chain(fence);
-		struct dma_fence *f = chain ? chain->fence : fence;
+		struct dma_fence *f = dma_fence_chain_contained(fence);
 
 		if (!dma_fence_is_signaled(f)) {
 			dma_fence_put(fence);

include/linux/dma-fence-chain.h

@@ -52,6 +52,21 @@ to_dma_fence_chain(struct dma_fence *fence)
 	return container_of(fence, struct dma_fence_chain, base);
 }
 
+/**
+ * dma_fence_chain_contained - return the contained fence
+ * @fence: the fence to test
+ *
+ * If the fence is a dma_fence_chain the function returns the fence contained
+ * inside the chain object, otherwise it returns the fence itself.
+ */
+static inline struct dma_fence *
+dma_fence_chain_contained(struct dma_fence *fence)
+{
+	struct dma_fence_chain *chain = to_dma_fence_chain(fence);
+
+	return chain ? chain->fence : fence;
+}
+
 /**
  * dma_fence_chain_alloc
  *