|
| 1 | +/* |
| 2 | + * Statically sized hash table implementation |
| 3 | + * (C) 2012 Sasha Levin <levinsasha928@gmail.com> |
| 4 | + */ |
| 5 | + |
| 6 | +#ifndef _LINUX_HASHTABLE_H |
| 7 | +#define _LINUX_HASHTABLE_H |
| 8 | + |
| 9 | +#include <linux/list.h> |
| 10 | +#include <linux/types.h> |
| 11 | +#include <linux/kernel.h> |
| 12 | +#include <linux/bitops.h> |
| 13 | +#include <linux/hash.h> |
| 14 | +#include <linux/log2.h> |
| 15 | + |
| 16 | +#ifndef ARRAY_SIZE |
| 17 | +#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) |
| 18 | +#endif |
| 19 | + |
| 20 | +#define DEFINE_HASHTABLE(name, bits) \ |
| 21 | + struct hlist_head name[1 << (bits)] = \ |
| 22 | + { [0 ... ((1 << (bits)) - 1)] = HLIST_HEAD_INIT } |
| 23 | + |
| 24 | +#define DECLARE_HASHTABLE(name, bits) \ |
| 25 | + struct hlist_head name[1 << (bits)] |
| 26 | + |
| 27 | +#define HASH_SIZE(name) (ARRAY_SIZE(name)) |
| 28 | +#define HASH_BITS(name) ilog2(HASH_SIZE(name)) |
| 29 | + |
| 30 | +/* Use hash_32 when possible to allow for fast 32bit hashing in 64bit kernels. */ |
| 31 | +#define hash_min(val, bits) \ |
| 32 | + (sizeof(val) <= 4 ? hash_32(val, bits) : hash_long(val, bits)) |
| 33 | + |
| 34 | +static inline void __hash_init(struct hlist_head *ht, unsigned int sz) |
| 35 | +{ |
| 36 | + unsigned int i; |
| 37 | + |
| 38 | + for (i = 0; i < sz; i++) |
| 39 | + INIT_HLIST_HEAD(&ht[i]); |
| 40 | +} |
| 41 | + |
| 42 | +/** |
| 43 | + * hash_init - initialize a hash table |
| 44 | + * @hashtable: hashtable to be initialized |
| 45 | + * |
| 46 | + * Calculates the size of the hashtable from the given parameter, otherwise |
| 47 | + * same as hash_init_size. |
| 48 | + * |
| 49 | + * This has to be a macro since HASH_BITS() will not work on pointers since |
| 50 | + * it calculates the size during preprocessing. |
| 51 | + */ |
| 52 | +#define hash_init(hashtable) __hash_init(hashtable, HASH_SIZE(hashtable)) |
| 53 | + |
| 54 | +/** |
| 55 | + * hash_add - add an object to a hashtable |
| 56 | + * @hashtable: hashtable to add to |
| 57 | + * @node: the &struct hlist_node of the object to be added |
| 58 | + * @key: the key of the object to be added |
| 59 | + */ |
| 60 | +#define hash_add(hashtable, node, key) \ |
| 61 | + hlist_add_head(node, &hashtable[hash_min(key, HASH_BITS(hashtable))]) |
| 62 | + |
| 63 | +/** |
| 64 | + * hash_hashed - check whether an object is in any hashtable |
| 65 | + * @node: the &struct hlist_node of the object to be checked |
| 66 | + */ |
| 67 | +static inline bool hash_hashed(struct hlist_node *node) |
| 68 | +{ |
| 69 | + return !hlist_unhashed(node); |
| 70 | +} |
| 71 | + |
| 72 | +static inline bool __hash_empty(struct hlist_head *ht, unsigned int sz) |
| 73 | +{ |
| 74 | + unsigned int i; |
| 75 | + |
| 76 | + for (i = 0; i < sz; i++) |
| 77 | + if (!hlist_empty(&ht[i])) |
| 78 | + return false; |
| 79 | + |
| 80 | + return true; |
| 81 | +} |
| 82 | + |
| 83 | +/** |
| 84 | + * hash_empty - check whether a hashtable is empty |
| 85 | + * @hashtable: hashtable to check |
| 86 | + * |
| 87 | + * This has to be a macro since HASH_BITS() will not work on pointers since |
| 88 | + * it calculates the size during preprocessing. |
| 89 | + */ |
| 90 | +#define hash_empty(hashtable) __hash_empty(hashtable, HASH_SIZE(hashtable)) |
| 91 | + |
| 92 | +/** |
| 93 | + * hash_del - remove an object from a hashtable |
| 94 | + * @node: &struct hlist_node of the object to remove |
| 95 | + */ |
| 96 | +static inline void hash_del(struct hlist_node *node) |
| 97 | +{ |
| 98 | + hlist_del_init(node); |
| 99 | +} |
| 100 | + |
| 101 | +/** |
| 102 | + * hash_for_each - iterate over a hashtable |
| 103 | + * @name: hashtable to iterate |
| 104 | + * @bkt: integer to use as bucket loop cursor |
| 105 | + * @obj: the type * to use as a loop cursor for each entry |
| 106 | + * @member: the name of the hlist_node within the struct |
| 107 | + */ |
| 108 | +#define hash_for_each(name, bkt, obj, member) \ |
| 109 | + for ((bkt) = 0, obj = NULL; obj == NULL && (bkt) < HASH_SIZE(name);\ |
| 110 | + (bkt)++)\ |
| 111 | + hlist_for_each_entry(obj, &name[bkt], member) |
| 112 | + |
| 113 | +/** |
| 114 | + * hash_for_each_safe - iterate over a hashtable safe against removal of |
| 115 | + * hash entry |
| 116 | + * @name: hashtable to iterate |
| 117 | + * @bkt: integer to use as bucket loop cursor |
| 118 | + * @tmp: a &struct used for temporary storage |
| 119 | + * @obj: the type * to use as a loop cursor for each entry |
| 120 | + * @member: the name of the hlist_node within the struct |
| 121 | + */ |
| 122 | +#define hash_for_each_safe(name, bkt, tmp, obj, member) \ |
| 123 | + for ((bkt) = 0, obj = NULL; obj == NULL && (bkt) < HASH_SIZE(name);\ |
| 124 | + (bkt)++)\ |
| 125 | + hlist_for_each_entry_safe(obj, tmp, &name[bkt], member) |
| 126 | + |
| 127 | +/** |
| 128 | + * hash_for_each_possible - iterate over all possible objects hashing to the |
| 129 | + * same bucket |
| 130 | + * @name: hashtable to iterate |
| 131 | + * @obj: the type * to use as a loop cursor for each entry |
| 132 | + * @member: the name of the hlist_node within the struct |
| 133 | + * @key: the key of the objects to iterate over |
| 134 | + */ |
| 135 | +#define hash_for_each_possible(name, obj, member, key) \ |
| 136 | + hlist_for_each_entry(obj, &name[hash_min(key, HASH_BITS(name))], member) |
| 137 | + |
| 138 | +/** |
| 139 | + * hash_for_each_possible_safe - iterate over all possible objects hashing to the |
| 140 | + * same bucket safe against removals |
| 141 | + * @name: hashtable to iterate |
| 142 | + * @obj: the type * to use as a loop cursor for each entry |
| 143 | + * @tmp: a &struct used for temporary storage |
| 144 | + * @member: the name of the hlist_node within the struct |
| 145 | + * @key: the key of the objects to iterate over |
| 146 | + */ |
| 147 | +#define hash_for_each_possible_safe(name, obj, tmp, member, key) \ |
| 148 | + hlist_for_each_entry_safe(obj, tmp,\ |
| 149 | + &name[hash_min(key, HASH_BITS(name))], member) |
| 150 | + |
| 151 | + |
| 152 | +#endif |
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