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-rw-r--r--include/linux/dma-fence-unwrap.h75
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diff --git a/include/linux/dma-fence-unwrap.h b/include/linux/dma-fence-unwrap.h
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+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2022 Advanced Micro Devices, Inc.
+ * Authors:
+ * Christian König <christian.koenig@amd.com>
+ */
+
+#ifndef __LINUX_DMA_FENCE_UNWRAP_H
+#define __LINUX_DMA_FENCE_UNWRAP_H
+
+struct dma_fence;
+
+/**
+ * struct dma_fence_unwrap - cursor into the container structure
+ *
+ * Should be used with dma_fence_unwrap_for_each() iterator macro.
+ */
+struct dma_fence_unwrap {
+ /**
+ * @chain: potential dma_fence_chain, but can be other fence as well
+ */
+ struct dma_fence *chain;
+ /**
+ * @array: potential dma_fence_array, but can be other fence as well
+ */
+ struct dma_fence *array;
+ /**
+ * @index: last returned index if @array is really a dma_fence_array
+ */
+ unsigned int index;
+};
+
+struct dma_fence *dma_fence_unwrap_first(struct dma_fence *head,
+ struct dma_fence_unwrap *cursor);
+struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor);
+
+/**
+ * dma_fence_unwrap_for_each - iterate over all fences in containers
+ * @fence: current fence
+ * @cursor: current position inside the containers
+ * @head: starting point for the iterator
+ *
+ * Unwrap dma_fence_chain and dma_fence_array containers and deep dive into all
+ * potential fences in them. If @head is just a normal fence only that one is
+ * returned.
+ */
+#define dma_fence_unwrap_for_each(fence, cursor, head) \
+ for (fence = dma_fence_unwrap_first(head, cursor); fence; \
+ fence = dma_fence_unwrap_next(cursor))
+
+struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences,
+ struct dma_fence **fences,
+ struct dma_fence_unwrap *cursors);
+
+/**
+ * dma_fence_unwrap_merge - unwrap and merge fences
+ *
+ * All fences given as parameters are unwrapped and merged back together as flat
+ * dma_fence_array. Useful if multiple containers need to be merged together.
+ *
+ * Implemented as a macro to allocate the necessary arrays on the stack and
+ * account the stack frame size to the caller.
+ *
+ * Returns NULL on memory allocation failure, a dma_fence object representing
+ * all the given fences otherwise.
+ */
+#define dma_fence_unwrap_merge(...) \
+ ({ \
+ struct dma_fence *__f[] = { __VA_ARGS__ }; \
+ struct dma_fence_unwrap __c[ARRAY_SIZE(__f)]; \
+ \
+ __dma_fence_unwrap_merge(ARRAY_SIZE(__f), __f, __c); \
+ })
+
+#endif