183 lines
5.5 KiB
C
183 lines
5.5 KiB
C
/* Private definitions for the generic associative array implementation.
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*
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* See Documentation/core-api/assoc_array.rst for information.
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*
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* Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#ifndef _LINUX_ASSOC_ARRAY_PRIV_H
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#define _LINUX_ASSOC_ARRAY_PRIV_H
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#ifdef CONFIG_ASSOCIATIVE_ARRAY
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#include <linux/assoc_array.h>
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#define ASSOC_ARRAY_FAN_OUT 16 /* Number of slots per node */
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#define ASSOC_ARRAY_FAN_MASK (ASSOC_ARRAY_FAN_OUT - 1)
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#define ASSOC_ARRAY_LEVEL_STEP (ilog2(ASSOC_ARRAY_FAN_OUT))
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#define ASSOC_ARRAY_LEVEL_STEP_MASK (ASSOC_ARRAY_LEVEL_STEP - 1)
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#define ASSOC_ARRAY_KEY_CHUNK_MASK (ASSOC_ARRAY_KEY_CHUNK_SIZE - 1)
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#define ASSOC_ARRAY_KEY_CHUNK_SHIFT (ilog2(BITS_PER_LONG))
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/*
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* Undefined type representing a pointer with type information in the bottom
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* two bits.
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*/
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struct assoc_array_ptr;
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/*
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* An N-way node in the tree.
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*
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* Each slot contains one of four things:
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*
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* (1) Nothing (NULL).
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*
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* (2) A leaf object (pointer types 0).
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*
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* (3) A next-level node (pointer type 1, subtype 0).
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*
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* (4) A shortcut (pointer type 1, subtype 1).
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*
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* The tree is optimised for search-by-ID, but permits reasonable iteration
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* also.
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*
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* The tree is navigated by constructing an index key consisting of an array of
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* segments, where each segment is ilog2(ASSOC_ARRAY_FAN_OUT) bits in size.
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*
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* The segments correspond to levels of the tree (the first segment is used at
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* level 0, the second at level 1, etc.).
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*/
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struct assoc_array_node {
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struct assoc_array_ptr *back_pointer;
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u8 parent_slot;
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struct assoc_array_ptr *slots[ASSOC_ARRAY_FAN_OUT];
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unsigned long nr_leaves_on_branch;
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};
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/*
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* A shortcut through the index space out to where a collection of nodes/leaves
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* with the same IDs live.
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*/
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struct assoc_array_shortcut {
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struct assoc_array_ptr *back_pointer;
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int parent_slot;
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int skip_to_level;
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struct assoc_array_ptr *next_node;
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unsigned long index_key[];
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};
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/*
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* Preallocation cache.
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*/
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struct assoc_array_edit {
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struct rcu_head rcu;
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struct assoc_array *array;
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const struct assoc_array_ops *ops;
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const struct assoc_array_ops *ops_for_excised_subtree;
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struct assoc_array_ptr *leaf;
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struct assoc_array_ptr **leaf_p;
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struct assoc_array_ptr *dead_leaf;
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struct assoc_array_ptr *new_meta[3];
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struct assoc_array_ptr *excised_meta[1];
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struct assoc_array_ptr *excised_subtree;
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struct assoc_array_ptr **set_backpointers[ASSOC_ARRAY_FAN_OUT];
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struct assoc_array_ptr *set_backpointers_to;
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struct assoc_array_node *adjust_count_on;
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long adjust_count_by;
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struct {
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struct assoc_array_ptr **ptr;
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struct assoc_array_ptr *to;
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} set[2];
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struct {
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u8 *p;
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u8 to;
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} set_parent_slot[1];
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u8 segment_cache[ASSOC_ARRAY_FAN_OUT + 1];
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};
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/*
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* Internal tree member pointers are marked in the bottom one or two bits to
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* indicate what type they are so that we don't have to look behind every
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* pointer to see what it points to.
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*
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* We provide functions to test type annotations and to create and translate
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* the annotated pointers.
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*/
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#define ASSOC_ARRAY_PTR_TYPE_MASK 0x1UL
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#define ASSOC_ARRAY_PTR_LEAF_TYPE 0x0UL /* Points to leaf (or nowhere) */
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#define ASSOC_ARRAY_PTR_META_TYPE 0x1UL /* Points to node or shortcut */
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#define ASSOC_ARRAY_PTR_SUBTYPE_MASK 0x2UL
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#define ASSOC_ARRAY_PTR_NODE_SUBTYPE 0x0UL
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#define ASSOC_ARRAY_PTR_SHORTCUT_SUBTYPE 0x2UL
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static inline bool assoc_array_ptr_is_meta(const struct assoc_array_ptr *x)
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{
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return (unsigned long)x & ASSOC_ARRAY_PTR_TYPE_MASK;
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}
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static inline bool assoc_array_ptr_is_leaf(const struct assoc_array_ptr *x)
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{
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return !assoc_array_ptr_is_meta(x);
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}
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static inline bool assoc_array_ptr_is_shortcut(const struct assoc_array_ptr *x)
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{
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return (unsigned long)x & ASSOC_ARRAY_PTR_SUBTYPE_MASK;
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}
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static inline bool assoc_array_ptr_is_node(const struct assoc_array_ptr *x)
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{
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return !assoc_array_ptr_is_shortcut(x);
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}
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static inline void *assoc_array_ptr_to_leaf(const struct assoc_array_ptr *x)
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{
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return (void *)((unsigned long)x & ~ASSOC_ARRAY_PTR_TYPE_MASK);
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}
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static inline
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unsigned long __assoc_array_ptr_to_meta(const struct assoc_array_ptr *x)
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{
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return (unsigned long)x &
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~(ASSOC_ARRAY_PTR_SUBTYPE_MASK | ASSOC_ARRAY_PTR_TYPE_MASK);
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}
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static inline
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struct assoc_array_node *assoc_array_ptr_to_node(const struct assoc_array_ptr *x)
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{
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return (struct assoc_array_node *)__assoc_array_ptr_to_meta(x);
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}
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static inline
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struct assoc_array_shortcut *assoc_array_ptr_to_shortcut(const struct assoc_array_ptr *x)
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{
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return (struct assoc_array_shortcut *)__assoc_array_ptr_to_meta(x);
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}
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static inline
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struct assoc_array_ptr *__assoc_array_x_to_ptr(const void *p, unsigned long t)
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{
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return (struct assoc_array_ptr *)((unsigned long)p | t);
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}
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static inline
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struct assoc_array_ptr *assoc_array_leaf_to_ptr(const void *p)
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{
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return __assoc_array_x_to_ptr(p, ASSOC_ARRAY_PTR_LEAF_TYPE);
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}
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static inline
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struct assoc_array_ptr *assoc_array_node_to_ptr(const struct assoc_array_node *p)
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{
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return __assoc_array_x_to_ptr(
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p, ASSOC_ARRAY_PTR_META_TYPE | ASSOC_ARRAY_PTR_NODE_SUBTYPE);
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}
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static inline
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struct assoc_array_ptr *assoc_array_shortcut_to_ptr(const struct assoc_array_shortcut *p)
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{
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return __assoc_array_x_to_ptr(
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p, ASSOC_ARRAY_PTR_META_TYPE | ASSOC_ARRAY_PTR_SHORTCUT_SUBTYPE);
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}
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#endif /* CONFIG_ASSOCIATIVE_ARRAY */
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#endif /* _LINUX_ASSOC_ARRAY_PRIV_H */
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