1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * Resizable, Scalable, Concurrent Hash Table
4 *
5 * Simple structures that might be needed in include
6 * files.
7 */
8
9 #ifndef _LINUX_RHASHTABLE_TYPES_H
10 #define _LINUX_RHASHTABLE_TYPES_H
11
12 #include <linux/atomic.h>
13 #include <linux/compiler.h>
14 #include <linux/mutex.h>
15 #include <linux/workqueue.h>
16
17 struct rhash_head {
18 struct rhash_head __rcu *next;
19 };
20
21 struct rhlist_head {
22 struct rhash_head rhead;
23 struct rhlist_head __rcu *next;
24 };
25
26 struct bucket_table;
27
28 /**
29 * struct rhashtable_compare_arg - Key for the function rhashtable_compare
30 * @ht: Hash table
31 * @key: Key to compare against
32 */
33 struct rhashtable_compare_arg {
34 struct rhashtable *ht;
35 const void *key;
36 };
37
38 typedef u32 (*rht_hashfn_t)(const void *data, u32 len, u32 seed);
39 typedef u32 (*rht_obj_hashfn_t)(const void *data, u32 len, u32 seed);
40 typedef int (*rht_obj_cmpfn_t)(struct rhashtable_compare_arg *arg,
41 const void *obj);
42
43 /**
44 * struct rhashtable_params - Hash table construction parameters
45 * @nelem_hint: Hint on number of elements, should be 75% of desired size
46 * @key_len: Length of key
47 * @key_offset: Offset of key in struct to be hashed
48 * @head_offset: Offset of rhash_head in struct to be hashed
49 * @max_size: Maximum size while expanding
50 * @min_size: Minimum size while shrinking
51 * @automatic_shrinking: Enable automatic shrinking of tables
52 * @hashfn: Hash function (default: jhash2 if !(key_len % 4), or jhash)
53 * @obj_hashfn: Function to hash object
54 * @obj_cmpfn: Function to compare key with object
55 */
56 struct rhashtable_params {
57 u16 nelem_hint;
58 u16 key_len;
59 u16 key_offset;
60 u16 head_offset;
61 unsigned int max_size;
62 u16 min_size;
63 bool automatic_shrinking;
64 rht_hashfn_t hashfn;
65 rht_obj_hashfn_t obj_hashfn;
66 rht_obj_cmpfn_t obj_cmpfn;
67 };
68
69 /**
70 * struct rhashtable - Hash table handle
71 * @tbl: Bucket table
72 * @key_len: Key length for hashfn
73 * @max_elems: Maximum number of elements in table
74 * @p: Configuration parameters
75 * @rhlist: True if this is an rhltable
76 * @run_work: Deferred worker to expand/shrink asynchronously
77 * @mutex: Mutex to protect current/future table swapping
78 * @lock: Spin lock to protect walker list
79 * @nelems: Number of elements in table
80 */
81 struct rhashtable {
82 struct bucket_table __rcu *tbl;
83 unsigned int key_len;
84 unsigned int max_elems;
85 struct rhashtable_params p;
86 bool rhlist;
87 struct work_struct run_work;
88 struct mutex mutex;
89 spinlock_t lock;
90 atomic_t nelems;
91 };
92
93 /**
94 * struct rhltable - Hash table with duplicate objects in a list
95 * @ht: Underlying rhtable
96 */
97 struct rhltable {
98 struct rhashtable ht;
99 };
100
101 /**
102 * struct rhashtable_walker - Hash table walker
103 * @list: List entry on list of walkers
104 * @tbl: The table that we were walking over
105 */
106 struct rhashtable_walker {
107 struct list_head list;
108 struct bucket_table *tbl;
109 };
110
111 /**
112 * struct rhashtable_iter - Hash table iterator
113 * @ht: Table to iterate through
114 * @p: Current pointer
115 * @list: Current hash list pointer
116 * @walker: Associated rhashtable walker
117 * @slot: Current slot
118 * @skip: Number of entries to skip in slot
119 */
120 struct rhashtable_iter {
121 struct rhashtable *ht;
122 struct rhash_head *p;
123 struct rhlist_head *list;
124 struct rhashtable_walker walker;
125 unsigned int slot;
126 unsigned int skip;
127 bool end_of_table;
128 };
129
130 int rhashtable_init(struct rhashtable *ht,
131 const struct rhashtable_params *params);
132 int rhltable_init(struct rhltable *hlt,
133 const struct rhashtable_params *params);
134
135 #endif /* _LINUX_RHASHTABLE_TYPES_H */