1 files changed, 59 insertions, 0 deletions
diff --git a/drivers/dma-buf/dma-fence-unwrap.c b/drivers/dma-buf/dma-fence-unwrap.c
new file mode 100644
index 000000000000..711be125428c
--- /dev/null
+++ b/drivers/dma-buf/dma-fence-unwrap.c
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * dma-fence-util: misc functions for dma_fence objects
+ *
+ * Copyright (C) 2022 Advanced Micro Devices, Inc.
+ * Authors:
+ *	Christian König <christian.koenig@amd.com>
+ */
+
+#include <linux/dma-fence.h>
+#include <linux/dma-fence-array.h>
+#include <linux/dma-fence-chain.h>
+#include <linux/dma-fence-unwrap.h>
+
+/* Internal helper to start new array iteration, don't use directly */
+static struct dma_fence *
+__dma_fence_unwrap_array(struct dma_fence_unwrap *cursor)
+{
+	cursor->array = dma_fence_chain_contained(cursor->chain);
+	cursor->index = 0;
+	return dma_fence_array_first(cursor->array);
+}
+
+/**
+ * dma_fence_unwrap_first - return the first fence from fence containers
+ * @head: the entrypoint into the containers
+ * @cursor: current position inside the containers
+ *
+ * Unwraps potential dma_fence_chain/dma_fence_array containers and return the
+ * first fence.
+ */
+struct dma_fence *dma_fence_unwrap_first(struct dma_fence *head,
+					 struct dma_fence_unwrap *cursor)
+{
+	cursor->chain = dma_fence_get(head);
+	return __dma_fence_unwrap_array(cursor);
+}
+EXPORT_SYMBOL_GPL(dma_fence_unwrap_first);
+
+/**
+ * dma_fence_unwrap_next - return the next fence from a fence containers
+ * @cursor: current position inside the containers
+ *
+ * Continue unwrapping the dma_fence_chain/dma_fence_array containers and return
+ * the next fence from them.
+ */
+struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor)
+{
+	struct dma_fence *tmp;
+
+	++cursor->index;
+	tmp = dma_fence_array_next(cursor->array, cursor->index);
+	if (tmp)
+		return tmp;
+
+	cursor->chain = dma_fence_chain_walk(cursor->chain);
+	return __dma_fence_unwrap_array(cursor);
+}
+EXPORT_SYMBOL_GPL(dma_fence_unwrap_next);