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 * @locks_mul: Number of bucket locks to allocate per cpu (default: 32) 52 * @automatic_shrinking: Enable automatic shrinking of tables 53 * @nulls_base: Base value to generate nulls marker 54 * @hashfn: Hash function (default: jhash2 if !(key_len % 4), or jhash) 55 * @obj_hashfn: Function to hash object 56 * @obj_cmpfn: Function to compare key with object 57 */ 58 struct rhashtable_params { 59 u16 nelem_hint; 60 u16 key_len; 61 u16 key_offset; 62 u16 head_offset; 63 unsigned int max_size; 64 u16 min_size; 65 bool automatic_shrinking; 66 u8 locks_mul; 67 u32 nulls_base; 68 rht_hashfn_t hashfn; 69 rht_obj_hashfn_t obj_hashfn; 70 rht_obj_cmpfn_t obj_cmpfn; 71 }; 72 73 /** 74 * struct rhashtable - Hash table handle 75 * @tbl: Bucket table 76 * @key_len: Key length for hashfn 77 * @max_elems: Maximum number of elements in table 78 * @p: Configuration parameters 79 * @rhlist: True if this is an rhltable 80 * @run_work: Deferred worker to expand/shrink asynchronously 81 * @mutex: Mutex to protect current/future table swapping 82 * @lock: Spin lock to protect walker list 83 * @nelems: Number of elements in table 84 */ 85 struct rhashtable { 86 struct bucket_table __rcu *tbl; 87 unsigned int key_len; 88 unsigned int max_elems; 89 struct rhashtable_params p; 90 bool rhlist; 91 struct work_struct run_work; 92 struct mutex mutex; 93 spinlock_t lock; 94 atomic_t nelems; 95 }; 96 97 /** 98 * struct rhltable - Hash table with duplicate objects in a list 99 * @ht: Underlying rhtable 100 */ 101 struct rhltable { 102 struct rhashtable ht; 103 }; 104 105 /** 106 * struct rhashtable_walker - Hash table walker 107 * @list: List entry on list of walkers 108 * @tbl: The table that we were walking over 109 */ 110 struct rhashtable_walker { 111 struct list_head list; 112 struct bucket_table *tbl; 113 }; 114 115 /** 116 * struct rhashtable_iter - Hash table iterator 117 * @ht: Table to iterate through 118 * @p: Current pointer 119 * @list: Current hash list pointer 120 * @walker: Associated rhashtable walker 121 * @slot: Current slot 122 * @skip: Number of entries to skip in slot 123 */ 124 struct rhashtable_iter { 125 struct rhashtable *ht; 126 struct rhash_head *p; 127 struct rhlist_head *list; 128 struct rhashtable_walker walker; 129 unsigned int slot; 130 unsigned int skip; 131 bool end_of_table; 132 }; 133 134 int rhashtable_init(struct rhashtable *ht, 135 const struct rhashtable_params *params); 136 int rhltable_init(struct rhltable *hlt, 137 const struct rhashtable_params *params); 138 139 #endif /* _LINUX_RHASHTABLE_TYPES_H */ 140