--- /dev/null
+// SPDX-License-Identifier: MIT
+
+/*
+ * Copyright (C) 2022 Advanced Micro Devices, Inc.
+ */
+
+#include <linux/dma-fence-unwrap.h>
+#if 0
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/mm.h>
+#include <linux/sched/signal.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/random.h>
+#endif
+
+#include "selftest.h"
+
+#define CHAIN_SZ (4 << 10)
+
+static inline struct mock_fence {
+ struct dma_fence base;
+ spinlock_t lock;
+} *to_mock_fence(struct dma_fence *f) {
+ return container_of(f, struct mock_fence, base);
+}
+
+static const char *mock_name(struct dma_fence *f)
+{
+ return "mock";
+}
+
+static const struct dma_fence_ops mock_ops = {
+ .get_driver_name = mock_name,
+ .get_timeline_name = mock_name,
+};
+
+static struct dma_fence *mock_fence(void)
+{
+ struct mock_fence *f;
+
+ f = kmalloc(sizeof(*f), GFP_KERNEL);
+ if (!f)
+ return NULL;
+
+ spin_lock_init(&f->lock);
+ dma_fence_init(&f->base, &mock_ops, &f->lock, 0, 0);
+
+ return &f->base;
+}
+
+static struct dma_fence *mock_array(unsigned int num_fences, ...)
+{
+ struct dma_fence_array *array;
+ struct dma_fence **fences;
+ va_list valist;
+ int i;
+
+ fences = kcalloc(num_fences, sizeof(*fences), GFP_KERNEL);
+ if (!fences)
+ return NULL;
+
+ va_start(valist, num_fences);
+ for (i = 0; i < num_fences; ++i)
+ fences[i] = va_arg(valist, typeof(*fences));
+ va_end(valist);
+
+ array = dma_fence_array_create(num_fences, fences,
+ dma_fence_context_alloc(1),
+ 1, false);
+ if (!array)
+ goto cleanup;
+ return &array->base;
+
+cleanup:
+ for (i = 0; i < num_fences; ++i)
+ dma_fence_put(fences[i]);
+ kfree(fences);
+ return NULL;
+}
+
+static struct dma_fence *mock_chain(struct dma_fence *prev,
+ struct dma_fence *fence)
+{
+ struct dma_fence_chain *f;
+
+ f = dma_fence_chain_alloc();
+ if (!f) {
+ dma_fence_put(prev);
+ dma_fence_put(fence);
+ return NULL;
+ }
+
+ dma_fence_chain_init(f, prev, fence, 1);
+ return &f->base;
+}
+
+static int sanitycheck(void *arg)
+{
+ struct dma_fence *f, *chain, *array;
+ int err = 0;
+
+ f = mock_fence();
+ if (!f)
+ return -ENOMEM;
+
+ array = mock_array(1, f);
+ if (!array)
+ return -ENOMEM;
+
+ chain = mock_chain(NULL, array);
+ if (!chain)
+ return -ENOMEM;
+
+ dma_fence_signal(f);
+ dma_fence_put(chain);
+ return err;
+}
+
+static int unwrap_array(void *arg)
+{
+ struct dma_fence *fence, *f1, *f2, *array;
+ struct dma_fence_unwrap iter;
+ int err = 0;
+
+ f1 = mock_fence();
+ if (!f1)
+ return -ENOMEM;
+
+ f2 = mock_fence();
+ if (!f2) {
+ dma_fence_put(f1);
+ return -ENOMEM;
+ }
+
+ array = mock_array(2, f1, f2);
+ if (!array)
+ return -ENOMEM;
+
+ dma_fence_unwrap_for_each(fence, &iter, array) {
+ if (fence == f1) {
+ f1 = NULL;
+ } else if (fence == f2) {
+ f2 = NULL;
+ } else {
+ pr_err("Unexpected fence!\n");
+ err = -EINVAL;
+ }
+ }
+
+ if (f1 || f2) {
+ pr_err("Not all fences seen!\n");
+ err = -EINVAL;
+ }
+
+ dma_fence_signal(f1);
+ dma_fence_signal(f2);
+ dma_fence_put(array);
+ return 0;
+}
+
+static int unwrap_chain(void *arg)
+{
+ struct dma_fence *fence, *f1, *f2, *chain;
+ struct dma_fence_unwrap iter;
+ int err = 0;
+
+ f1 = mock_fence();
+ if (!f1)
+ return -ENOMEM;
+
+ f2 = mock_fence();
+ if (!f2) {
+ dma_fence_put(f1);
+ return -ENOMEM;
+ }
+
+ chain = mock_chain(f1, f2);
+ if (!chain)
+ return -ENOMEM;
+
+ dma_fence_unwrap_for_each(fence, &iter, chain) {
+ if (fence == f1) {
+ f1 = NULL;
+ } else if (fence == f2) {
+ f2 = NULL;
+ } else {
+ pr_err("Unexpected fence!\n");
+ err = -EINVAL;
+ }
+ }
+
+ if (f1 || f2) {
+ pr_err("Not all fences seen!\n");
+ err = -EINVAL;
+ }
+
+ dma_fence_signal(f1);
+ dma_fence_signal(f2);
+ dma_fence_put(chain);
+ return 0;
+}
+
+static int unwrap_chain_array(void *arg)
+{
+ struct dma_fence *fence, *f1, *f2, *array, *chain;
+ struct dma_fence_unwrap iter;
+ int err = 0;
+
+ f1 = mock_fence();
+ if (!f1)
+ return -ENOMEM;
+
+ f2 = mock_fence();
+ if (!f2) {
+ dma_fence_put(f1);
+ return -ENOMEM;
+ }
+
+ array = mock_array(2, f1, f2);
+ if (!array)
+ return -ENOMEM;
+
+ chain = mock_chain(NULL, array);
+ if (!chain)
+ return -ENOMEM;
+
+ dma_fence_unwrap_for_each(fence, &iter, chain) {
+ if (fence == f1) {
+ f1 = NULL;
+ } else if (fence == f2) {
+ f2 = NULL;
+ } else {
+ pr_err("Unexpected fence!\n");
+ err = -EINVAL;
+ }
+ }
+
+ if (f1 || f2) {
+ pr_err("Not all fences seen!\n");
+ err = -EINVAL;
+ }
+
+ dma_fence_signal(f1);
+ dma_fence_signal(f2);
+ dma_fence_put(chain);
+ return 0;
+}
+
+int dma_fence_unwrap(void)
+{
+ static const struct subtest tests[] = {
+ SUBTEST(sanitycheck),
+ SUBTEST(unwrap_array),
+ SUBTEST(unwrap_chain),
+ SUBTEST(unwrap_chain_array),
+ };
+
+ return subtests(tests, NULL);
+}
--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * fence-chain: chain fences together in a timeline
+ *
+ * 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
+
+#include <linux/dma-fence-chain.h>
+#include <linux/dma-fence-array.h>
+
+/**
+ * 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;
+};
+
+/* Internal helper to start new array iteration, don't use directly */
+static inline 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.
+ */
+static inline 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);
+}
+
+/**
+ * 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.
+ */
+static inline 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);
+}
+
+/**
+ * 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))
+
+#endif
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