[PATCH 6/9] dma-buf: add dma_fence_chain_contained helper

["Christian König" <ckoenig.leichtzumerken@gmail.com>]

It's a reoccurring pattern that we need to extract the fence
from a dma_fence_chain object. Add a helper for this.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-fence-chain.c |  6 ++----
 include/linux/dma-fence-chain.h   | 15 +++++++++++++++
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/dma-buf/dma-fence-chain.c b/drivers/dma-buf/dma-fence-chain.c
index fa33f6b7f77b..2f497ffb70d8 100644
--- a/drivers/dma-buf/dma-fence-chain.c
+++ b/drivers/dma-buf/dma-fence-chain.c
@@ -148,8 +148,7 @@ 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)) {
@@ -165,8 +164,7 @@ 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);
diff --git a/include/linux/dma-fence-chain.h b/include/linux/dma-fence-chain.h
index ee906b659694..10d51bcdf7b7 100644
--- a/include/linux/dma-fence-chain.h
+++ b/include/linux/dma-fence-chain.h
@@ -66,6 +66,21 @@ 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
  *
-- 
2.25.1