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1/* SPDX-License-Identifier: GPL-2.0-or-later */2/* Private definitions for the generic associative array implementation.3 *4 * See Documentation/core-api/assoc_array.rst for information.5 *6 * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.7 * Written by David Howells (dhowells@redhat.com)8 */9 10#ifndef _LINUX_ASSOC_ARRAY_PRIV_H11#define _LINUX_ASSOC_ARRAY_PRIV_H12 13#ifdef CONFIG_ASSOCIATIVE_ARRAY14 15#include <linux/assoc_array.h>16 17#define ASSOC_ARRAY_FAN_OUT 16 /* Number of slots per node */18#define ASSOC_ARRAY_FAN_MASK (ASSOC_ARRAY_FAN_OUT - 1)19#define ASSOC_ARRAY_LEVEL_STEP (ilog2(ASSOC_ARRAY_FAN_OUT))20#define ASSOC_ARRAY_LEVEL_STEP_MASK (ASSOC_ARRAY_LEVEL_STEP - 1)21#define ASSOC_ARRAY_KEY_CHUNK_MASK (ASSOC_ARRAY_KEY_CHUNK_SIZE - 1)22#define ASSOC_ARRAY_KEY_CHUNK_SHIFT (ilog2(BITS_PER_LONG))23 24/*25 * Undefined type representing a pointer with type information in the bottom26 * two bits.27 */28struct assoc_array_ptr;29 30/*31 * An N-way node in the tree.32 *33 * Each slot contains one of four things:34 *35 * (1) Nothing (NULL).36 *37 * (2) A leaf object (pointer types 0).38 *39 * (3) A next-level node (pointer type 1, subtype 0).40 *41 * (4) A shortcut (pointer type 1, subtype 1).42 *43 * The tree is optimised for search-by-ID, but permits reasonable iteration44 * also.45 *46 * The tree is navigated by constructing an index key consisting of an array of47 * segments, where each segment is ilog2(ASSOC_ARRAY_FAN_OUT) bits in size.48 *49 * The segments correspond to levels of the tree (the first segment is used at50 * level 0, the second at level 1, etc.).51 */52struct assoc_array_node {53 struct assoc_array_ptr *back_pointer;54 u8 parent_slot;55 struct assoc_array_ptr *slots[ASSOC_ARRAY_FAN_OUT];56 unsigned long nr_leaves_on_branch;57};58 59/*60 * A shortcut through the index space out to where a collection of nodes/leaves61 * with the same IDs live.62 */63struct assoc_array_shortcut {64 struct assoc_array_ptr *back_pointer;65 int parent_slot;66 int skip_to_level;67 struct assoc_array_ptr *next_node;68 unsigned long index_key[];69};70 71/*72 * Preallocation cache.73 */74struct assoc_array_edit {75 struct rcu_head rcu;76 struct assoc_array *array;77 const struct assoc_array_ops *ops;78 const struct assoc_array_ops *ops_for_excised_subtree;79 struct assoc_array_ptr *leaf;80 struct assoc_array_ptr **leaf_p;81 struct assoc_array_ptr *dead_leaf;82 struct assoc_array_ptr *new_meta[3];83 struct assoc_array_ptr *excised_meta[1];84 struct assoc_array_ptr *excised_subtree;85 struct assoc_array_ptr **set_backpointers[ASSOC_ARRAY_FAN_OUT];86 struct assoc_array_ptr *set_backpointers_to;87 struct assoc_array_node *adjust_count_on;88 long adjust_count_by;89 struct {90 struct assoc_array_ptr **ptr;91 struct assoc_array_ptr *to;92 } set[2];93 struct {94 u8 *p;95 u8 to;96 } set_parent_slot[1];97 u8 segment_cache[ASSOC_ARRAY_FAN_OUT + 1];98};99 100/*101 * Internal tree member pointers are marked in the bottom one or two bits to102 * indicate what type they are so that we don't have to look behind every103 * pointer to see what it points to.104 *105 * We provide functions to test type annotations and to create and translate106 * the annotated pointers.107 */108#define ASSOC_ARRAY_PTR_TYPE_MASK 0x1UL109#define ASSOC_ARRAY_PTR_LEAF_TYPE 0x0UL /* Points to leaf (or nowhere) */110#define ASSOC_ARRAY_PTR_META_TYPE 0x1UL /* Points to node or shortcut */111#define ASSOC_ARRAY_PTR_SUBTYPE_MASK 0x2UL112#define ASSOC_ARRAY_PTR_NODE_SUBTYPE 0x0UL113#define ASSOC_ARRAY_PTR_SHORTCUT_SUBTYPE 0x2UL114 115static inline bool assoc_array_ptr_is_meta(const struct assoc_array_ptr *x)116{117 return (unsigned long)x & ASSOC_ARRAY_PTR_TYPE_MASK;118}119static inline bool assoc_array_ptr_is_leaf(const struct assoc_array_ptr *x)120{121 return !assoc_array_ptr_is_meta(x);122}123static inline bool assoc_array_ptr_is_shortcut(const struct assoc_array_ptr *x)124{125 return (unsigned long)x & ASSOC_ARRAY_PTR_SUBTYPE_MASK;126}127static inline bool assoc_array_ptr_is_node(const struct assoc_array_ptr *x)128{129 return !assoc_array_ptr_is_shortcut(x);130}131 132static inline void *assoc_array_ptr_to_leaf(const struct assoc_array_ptr *x)133{134 return (void *)((unsigned long)x & ~ASSOC_ARRAY_PTR_TYPE_MASK);135}136 137static inline138unsigned long __assoc_array_ptr_to_meta(const struct assoc_array_ptr *x)139{140 return (unsigned long)x &141 ~(ASSOC_ARRAY_PTR_SUBTYPE_MASK | ASSOC_ARRAY_PTR_TYPE_MASK);142}143static inline144struct assoc_array_node *assoc_array_ptr_to_node(const struct assoc_array_ptr *x)145{146 return (struct assoc_array_node *)__assoc_array_ptr_to_meta(x);147}148static inline149struct assoc_array_shortcut *assoc_array_ptr_to_shortcut(const struct assoc_array_ptr *x)150{151 return (struct assoc_array_shortcut *)__assoc_array_ptr_to_meta(x);152}153 154static inline155struct assoc_array_ptr *__assoc_array_x_to_ptr(const void *p, unsigned long t)156{157 return (struct assoc_array_ptr *)((unsigned long)p | t);158}159static inline160struct assoc_array_ptr *assoc_array_leaf_to_ptr(const void *p)161{162 return __assoc_array_x_to_ptr(p, ASSOC_ARRAY_PTR_LEAF_TYPE);163}164static inline165struct assoc_array_ptr *assoc_array_node_to_ptr(const struct assoc_array_node *p)166{167 return __assoc_array_x_to_ptr(168 p, ASSOC_ARRAY_PTR_META_TYPE | ASSOC_ARRAY_PTR_NODE_SUBTYPE);169}170static inline171struct assoc_array_ptr *assoc_array_shortcut_to_ptr(const struct assoc_array_shortcut *p)172{173 return __assoc_array_x_to_ptr(174 p, ASSOC_ARRAY_PTR_META_TYPE | ASSOC_ARRAY_PTR_SHORTCUT_SUBTYPE);175}176 177#endif /* CONFIG_ASSOCIATIVE_ARRAY */178#endif /* _LINUX_ASSOC_ARRAY_PRIV_H */179