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Thomas Graf7e1e7762014-08-02 11:47:44 +02001/*
2 * Resizable, Scalable, Concurrent Hash Table
3 *
4 * Copyright (c) 2014 Thomas Graf <tgraf@suug.ch>
5 * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net>
6 *
7 * Based on the following paper by Josh Triplett, Paul E. McKenney
8 * and Jonathan Walpole:
9 * https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf
10 *
11 * Code partially derived from nft_hash
12 *
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License version 2 as
15 * published by the Free Software Foundation.
16 */
17
18#ifndef _LINUX_RHASHTABLE_H
19#define _LINUX_RHASHTABLE_H
20
21#include <linux/rculist.h>
22
23struct rhash_head {
Thomas Graf5300fdc2014-08-13 16:38:29 +020024 struct rhash_head __rcu *next;
Thomas Graf7e1e7762014-08-02 11:47:44 +020025};
26
27#define INIT_HASH_HEAD(ptr) ((ptr)->next = NULL)
28
29struct bucket_table {
30 size_t size;
31 struct rhash_head __rcu *buckets[];
32};
33
34typedef u32 (*rht_hashfn_t)(const void *data, u32 len, u32 seed);
35typedef u32 (*rht_obj_hashfn_t)(const void *data, u32 seed);
36
37struct rhashtable;
38
39/**
40 * struct rhashtable_params - Hash table construction parameters
41 * @nelem_hint: Hint on number of elements, should be 75% of desired size
42 * @key_len: Length of key
43 * @key_offset: Offset of key in struct to be hashed
44 * @head_offset: Offset of rhash_head in struct to be hashed
45 * @hash_rnd: Seed to use while hashing
46 * @max_shift: Maximum number of shifts while expanding
47 * @hashfn: Function to hash key
48 * @obj_hashfn: Function to hash object
49 * @grow_decision: If defined, may return true if table should expand
50 * @shrink_decision: If defined, may return true if table should shrink
51 * @mutex_is_held: Must return true if protecting mutex is held
52 */
53struct rhashtable_params {
54 size_t nelem_hint;
55 size_t key_len;
56 size_t key_offset;
57 size_t head_offset;
58 u32 hash_rnd;
59 size_t max_shift;
60 rht_hashfn_t hashfn;
61 rht_obj_hashfn_t obj_hashfn;
62 bool (*grow_decision)(const struct rhashtable *ht,
63 size_t new_size);
64 bool (*shrink_decision)(const struct rhashtable *ht,
65 size_t new_size);
66 int (*mutex_is_held)(void);
67};
68
69/**
70 * struct rhashtable - Hash table handle
71 * @tbl: Bucket table
72 * @nelems: Number of elements in table
73 * @shift: Current size (1 << shift)
74 * @p: Configuration parameters
75 */
76struct rhashtable {
77 struct bucket_table __rcu *tbl;
78 size_t nelems;
79 size_t shift;
80 struct rhashtable_params p;
81};
82
83#ifdef CONFIG_PROVE_LOCKING
84int lockdep_rht_mutex_is_held(const struct rhashtable *ht);
85#else
86static inline int lockdep_rht_mutex_is_held(const struct rhashtable *ht)
87{
88 return 1;
89}
90#endif /* CONFIG_PROVE_LOCKING */
91
92int rhashtable_init(struct rhashtable *ht, struct rhashtable_params *params);
93
94u32 rhashtable_hashfn(const struct rhashtable *ht, const void *key, u32 len);
95u32 rhashtable_obj_hashfn(const struct rhashtable *ht, void *ptr);
96
97void rhashtable_insert(struct rhashtable *ht, struct rhash_head *node, gfp_t);
98bool rhashtable_remove(struct rhashtable *ht, struct rhash_head *node, gfp_t);
99void rhashtable_remove_pprev(struct rhashtable *ht, struct rhash_head *obj,
Thomas Graf5300fdc2014-08-13 16:38:29 +0200100 struct rhash_head __rcu **pprev, gfp_t flags);
Thomas Graf7e1e7762014-08-02 11:47:44 +0200101
102bool rht_grow_above_75(const struct rhashtable *ht, size_t new_size);
103bool rht_shrink_below_30(const struct rhashtable *ht, size_t new_size);
104
105int rhashtable_expand(struct rhashtable *ht, gfp_t flags);
106int rhashtable_shrink(struct rhashtable *ht, gfp_t flags);
107
108void *rhashtable_lookup(const struct rhashtable *ht, const void *key);
109void *rhashtable_lookup_compare(const struct rhashtable *ht, u32 hash,
110 bool (*compare)(void *, void *), void *arg);
111
112void rhashtable_destroy(const struct rhashtable *ht);
113
114#define rht_dereference(p, ht) \
115 rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht))
116
117#define rht_dereference_rcu(p, ht) \
118 rcu_dereference_check(p, lockdep_rht_mutex_is_held(ht))
119
Thomas Graf7e1e7762014-08-02 11:47:44 +0200120#define rht_entry(ptr, type, member) container_of(ptr, type, member)
121#define rht_entry_safe(ptr, type, member) \
122({ \
123 typeof(ptr) __ptr = (ptr); \
124 __ptr ? rht_entry(__ptr, type, member) : NULL; \
125})
Thomas Graf7e1e7762014-08-02 11:47:44 +0200126
127#define rht_next_entry_safe(pos, ht, member) \
128({ \
129 pos ? rht_entry_safe(rht_dereference((pos)->member.next, ht), \
130 typeof(*(pos)), member) : NULL; \
131})
132
133/**
134 * rht_for_each - iterate over hash chain
135 * @pos: &struct rhash_head to use as a loop cursor.
136 * @head: head of the hash chain (struct rhash_head *)
137 * @ht: pointer to your struct rhashtable
138 */
139#define rht_for_each(pos, head, ht) \
140 for (pos = rht_dereference(head, ht); \
141 pos; \
142 pos = rht_dereference((pos)->next, ht))
143
144/**
145 * rht_for_each_entry - iterate over hash chain of given type
146 * @pos: type * to use as a loop cursor.
147 * @head: head of the hash chain (struct rhash_head *)
148 * @ht: pointer to your struct rhashtable
149 * @member: name of the rhash_head within the hashable struct.
150 */
151#define rht_for_each_entry(pos, head, ht, member) \
152 for (pos = rht_entry_safe(rht_dereference(head, ht), \
153 typeof(*(pos)), member); \
154 pos; \
155 pos = rht_next_entry_safe(pos, ht, member))
156
157/**
158 * rht_for_each_entry_safe - safely iterate over hash chain of given type
159 * @pos: type * to use as a loop cursor.
160 * @n: type * to use for temporary next object storage
161 * @head: head of the hash chain (struct rhash_head *)
162 * @ht: pointer to your struct rhashtable
163 * @member: name of the rhash_head within the hashable struct.
164 *
165 * This hash chain list-traversal primitive allows for the looped code to
166 * remove the loop cursor from the list.
167 */
168#define rht_for_each_entry_safe(pos, n, head, ht, member) \
169 for (pos = rht_entry_safe(rht_dereference(head, ht), \
170 typeof(*(pos)), member), \
171 n = rht_next_entry_safe(pos, ht, member); \
172 pos; \
173 pos = n, \
174 n = rht_next_entry_safe(pos, ht, member))
175
176/**
177 * rht_for_each_rcu - iterate over rcu hash chain
178 * @pos: &struct rhash_head to use as a loop cursor.
179 * @head: head of the hash chain (struct rhash_head *)
180 * @ht: pointer to your struct rhashtable
181 *
182 * This hash chain list-traversal primitive may safely run concurrently with
183 * the _rcu fkht mutation primitives such as rht_insert() as long as the
184 * traversal is guarded by rcu_read_lock().
185 */
186#define rht_for_each_rcu(pos, head, ht) \
187 for (pos = rht_dereference_rcu(head, ht); \
188 pos; \
189 pos = rht_dereference_rcu((pos)->next, ht))
190
191/**
192 * rht_for_each_entry_rcu - iterate over rcu hash chain of given type
193 * @pos: type * to use as a loop cursor.
194 * @head: head of the hash chain (struct rhash_head *)
195 * @member: name of the rhash_head within the hashable struct.
196 *
197 * This hash chain list-traversal primitive may safely run concurrently with
198 * the _rcu fkht mutation primitives such as rht_insert() as long as the
199 * traversal is guarded by rcu_read_lock().
200 */
201#define rht_for_each_entry_rcu(pos, head, member) \
Thomas Graf93f560812014-08-13 16:38:31 +0200202 for (pos = rht_entry_safe(rcu_dereference_raw(head), \
203 typeof(*(pos)), member); \
Thomas Graf7e1e7762014-08-02 11:47:44 +0200204 pos; \
Thomas Graf93f560812014-08-13 16:38:31 +0200205 pos = rht_entry_safe(rcu_dereference_raw((pos)->member.next), \
206 typeof(*(pos)), member))
Thomas Graf7e1e7762014-08-02 11:47:44 +0200207
208#endif /* _LINUX_RHASHTABLE_H */