v4.19.13 snapshot.
diff --git a/include/linux/assoc_array.h b/include/linux/assoc_array.h
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+++ b/include/linux/assoc_array.h
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+/* Generic associative array implementation.
+ *
+ * See Documentation/core-api/assoc_array.rst for information.
+ *
+ * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#ifndef _LINUX_ASSOC_ARRAY_H
+#define _LINUX_ASSOC_ARRAY_H
+
+#ifdef CONFIG_ASSOCIATIVE_ARRAY
+
+#include <linux/types.h>
+
+#define ASSOC_ARRAY_KEY_CHUNK_SIZE BITS_PER_LONG /* Key data retrieved in chunks of this size */
+
+/*
+ * Generic associative array.
+ */
+struct assoc_array {
+ struct assoc_array_ptr *root; /* The node at the root of the tree */
+ unsigned long nr_leaves_on_tree;
+};
+
+/*
+ * Operations on objects and index keys for use by array manipulation routines.
+ */
+struct assoc_array_ops {
+ /* Method to get a chunk of an index key from caller-supplied data */
+ unsigned long (*get_key_chunk)(const void *index_key, int level);
+
+ /* Method to get a piece of an object's index key */
+ unsigned long (*get_object_key_chunk)(const void *object, int level);
+
+ /* Is this the object we're looking for? */
+ bool (*compare_object)(const void *object, const void *index_key);
+
+ /* How different is an object from an index key, to a bit position in
+ * their keys? (or -1 if they're the same)
+ */
+ int (*diff_objects)(const void *object, const void *index_key);
+
+ /* Method to free an object. */
+ void (*free_object)(void *object);
+};
+
+/*
+ * Access and manipulation functions.
+ */
+struct assoc_array_edit;
+
+static inline void assoc_array_init(struct assoc_array *array)
+{
+ array->root = NULL;
+ array->nr_leaves_on_tree = 0;
+}
+
+extern int assoc_array_iterate(const struct assoc_array *array,
+ int (*iterator)(const void *object,
+ void *iterator_data),
+ void *iterator_data);
+extern void *assoc_array_find(const struct assoc_array *array,
+ const struct assoc_array_ops *ops,
+ const void *index_key);
+extern void assoc_array_destroy(struct assoc_array *array,
+ const struct assoc_array_ops *ops);
+extern struct assoc_array_edit *assoc_array_insert(struct assoc_array *array,
+ const struct assoc_array_ops *ops,
+ const void *index_key,
+ void *object);
+extern void assoc_array_insert_set_object(struct assoc_array_edit *edit,
+ void *object);
+extern struct assoc_array_edit *assoc_array_delete(struct assoc_array *array,
+ const struct assoc_array_ops *ops,
+ const void *index_key);
+extern struct assoc_array_edit *assoc_array_clear(struct assoc_array *array,
+ const struct assoc_array_ops *ops);
+extern void assoc_array_apply_edit(struct assoc_array_edit *edit);
+extern void assoc_array_cancel_edit(struct assoc_array_edit *edit);
+extern int assoc_array_gc(struct assoc_array *array,
+ const struct assoc_array_ops *ops,
+ bool (*iterator)(void *object, void *iterator_data),
+ void *iterator_data);
+
+#endif /* CONFIG_ASSOCIATIVE_ARRAY */
+#endif /* _LINUX_ASSOC_ARRAY_H */