| 1 |
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| 2 | |
| 3 | * Resizable, Scalable, Concurrent Hash Table
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| 4 | *
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| 5 | * Copyright (c) 2015-2016 Herbert Xu <[email protected]>
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| 6 | * Copyright (c) 2014-2015 Thomas Graf <[email protected]>
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| 7 | * Copyright (c) 2008-2014 Patrick McHardy <[email protected]>
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| 8 | *
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| 9 | * Code partially derived from nft_hash
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| 10 | * Rewritten with rehash code from br_multicast plus single list
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| 11 | * pointer as suggested by Josh Triplett
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| 12 | *
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| 13 | * This program is free software; you can redistribute it and/or modify
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| 14 | * it under the terms of the GNU General Public License version 2 as
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| 15 | * published by the Free Software Foundation.
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| 16 |
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| 17 |
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| 18 | #ifndef _LINUX_RHASHTABLE_H
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| 19 | #define _LINUX_RHASHTABLE_H
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| 20 |
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| 21 | #include <linux/err.h>
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| 22 | #include <linux/errno.h>
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| 23 | #include <linux/jhash.h>
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| 24 | #include <linux/list_nulls.h>
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| 25 | #include <linux/workqueue.h>
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| 26 | #include <linux/rculist.h>
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| 27 | #include <linux/bit_spinlock.h>
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| 28 |
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| 29 | #include <linux/rhashtable-types.h>
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| 30 | |
| 31 | * Objects in an rhashtable have an embedded struct rhash_head
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| 32 | * which is linked into as hash chain from the hash table - or one
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| 33 | * of two or more hash tables when the rhashtable is being resized.
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| 34 | * The end of the chain is marked with a special nulls marks which has
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| 35 | * the least significant bit set but otherwise stores the address of
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| 36 | * the hash bucket. This allows us to be sure we've found the end
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| 37 | * of the right list.
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| 38 | * The value stored in the hash bucket has BIT(0) used as a lock bit.
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| 39 | * This bit must be atomically set before any changes are made to
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| 40 | * the chain. To avoid dereferencing this pointer without clearing
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| 41 | * the bit first, we use an opaque 'struct rhash_lock_head *' for the
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| 42 | * pointer stored in the bucket. This struct needs to be defined so
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| 43 | * that rcu_dereference() works on it, but it has no content so a
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| 44 | * cast is needed for it to be useful. This ensures it isn't
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| 45 | * used by mistake with clearing the lock bit first.
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| 46 |
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| 47 | struct rhash_lock_head {};
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| 48 |
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| 49 | |
| 50 | *
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| 51 | * The maximum (not average) chain length grows with the size of the hash
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| 52 | * table, at a rate of (log N)/(log log N).
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| 53 | *
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| 54 | * The value of 16 is selected so that even if the hash table grew to
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| 55 | * 2^32 you would not expect the maximum chain length to exceed it
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| 56 | * unless we are under attack (or extremely unlucky).
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| 57 | *
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| 58 | * As this limit is only to detect attacks, we don't need to set it to a
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| 59 | * lower value as you'd need the chain length to vastly exceed 16 to have
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| 60 | * any real effect on the system.
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| 61 |
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| 62 | #define RHT_ELASTICITY 16u
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| 63 |
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| 64 | |
| 65 | * struct bucket_table - Table of hash buckets
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| 66 | * @size: Number of hash buckets
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| 67 | * @nest: Number of bits of first-level nested table.
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| 68 | * @rehash: Current bucket being rehashed
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| 69 | * @hash_rnd: Random seed to fold into hash
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| 70 | * @walkers: List of active walkers
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| 71 | * @rcu: RCU structure for freeing the table
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| 72 | * @future_tbl: Table under construction during rehashing
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| 73 | * @ntbl: Nested table used when out of memory.
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| 74 | * @buckets: size * hash buckets
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| 75 |
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| 76 | struct bucket_table {
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| 77 | unsigned int size;
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| 78 | unsigned int nest;
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| 79 | u32 hash_rnd;
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| 80 | struct list_head walkers;
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| 81 | struct rcu_head rcu;
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| 82 |
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| 83 | struct bucket_table __rcu *future_tbl;
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| 84 |
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| 85 | struct lockdep_map dep_map;
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| 86 |
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| 87 | struct rhash_lock_head __rcu *buckets[] ____cacheline_aligned_in_smp;
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| 88 | };
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| 89 |
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| 90 | |
| 91 | * NULLS_MARKER() expects a hash value with the low
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| 92 | * bits mostly likely to be significant, and it discards
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| 93 | * the msb.
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| 94 | * We give it an address, in which the bottom bit is
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| 95 | * always 0, and the msb might be significant.
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| 96 | * So we shift the address down one bit to align with
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| 97 | * expectations and avoid losing a significant bit.
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| 98 | *
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| 99 | * We never store the NULLS_MARKER in the hash table
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| 100 | * itself as we need the lsb for locking.
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| 101 | * Instead we store a NULL
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| 102 |
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| 103 | #define RHT_NULLS_MARKER(ptr) \
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| 104 | ((void *)NULLS_MARKER(((unsigned long) (ptr)) >> 1))
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| 105 | #define INIT_RHT_NULLS_HEAD(ptr) \
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| 106 | ((ptr) = NULL)
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| 107 |
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| 108 | static inline bool rht_is_a_nulls(const struct rhash_head *ptr)
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| 109 | {
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| 110 | return ((unsigned long) ptr & 1);
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| 111 | }
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| 112 |
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| 113 | static inline void *rht_obj(const struct rhashtable *ht,
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| 114 | const struct rhash_head *he)
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| 115 | {
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| 116 | return (char *)he - ht->p.head_offset;
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| 117 | }
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| 118 |
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| 119 | static inline unsigned int rht_bucket_index(const struct bucket_table *tbl,
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| 120 | unsigned int hash)
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| 121 | {
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| 122 | return hash & (tbl->size - 1);
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| 123 | }
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| 124 |
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| 125 | static __always_inline unsigned int rht_key_get_hash(struct rhashtable *ht,
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| 126 | const void *key, const struct rhashtable_params params,
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| 127 | unsigned int hash_rnd)
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| 128 | {
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| 129 | unsigned int hash;
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| 130 |
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| 131 |
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| 132 | if (!__builtin_constant_p(params.key_len))
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| 133 | hash = ht->p.hashfn(key, ht->key_len, hash_rnd);
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| 134 | else if (params.key_len) {
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| 135 | unsigned int key_len = params.key_len;
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| 136 |
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| 137 | if (params.hashfn)
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| 138 | hash = params.hashfn(key, key_len, hash_rnd);
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| 139 | else if (key_len & (sizeof(u32) - 1))
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| 140 | hash = jhash(key, key_len, hash_rnd);
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| 141 | else
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| 142 | hash = jhash2(key, key_len / sizeof(u32), hash_rnd);
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| 143 | } else {
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| 144 | unsigned int key_len = ht->p.key_len;
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| 145 |
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| 146 | if (params.hashfn)
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| 147 | hash = params.hashfn(key, key_len, hash_rnd);
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| 148 | else
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| 149 | hash = jhash(key, key_len, hash_rnd);
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| 150 | }
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| 151 |
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| 152 | return hash;
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| 153 | }
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| 154 |
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| 155 | static __always_inline unsigned int rht_key_hashfn(
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| 156 | struct rhashtable *ht, const struct bucket_table *tbl,
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| 157 | const void *key, const struct rhashtable_params params)
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| 158 | {
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| 159 | unsigned int hash = rht_key_get_hash(ht, key, params, tbl->hash_rnd);
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| 160 |
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| 161 | return rht_bucket_index(tbl, hash);
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| 162 | }
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| 163 |
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| 164 | static __always_inline unsigned int rht_head_hashfn(
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| 165 | struct rhashtable *ht, const struct bucket_table *tbl,
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| 166 | const struct rhash_head *he, const struct rhashtable_params params)
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| 167 | {
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| 168 | const char *ptr = rht_obj(ht, he);
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| 169 |
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| 170 | return likely(params.obj_hashfn) ?
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| 171 | rht_bucket_index(tbl, params.obj_hashfn(ptr, params.key_len ?:
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| 172 | ht->p.key_len,
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| 173 | tbl->hash_rnd)) :
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| 174 | rht_key_hashfn(ht, tbl, ptr + params.key_offset, params);
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| 175 | }
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| 176 |
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| 177 | |
| 178 | * rht_grow_above_75 - returns true if nelems > 0.75 * table-size
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| 179 | * @ht: hash table
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| 180 | * @tbl: current table
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| 181 |
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| 182 | static inline bool rht_grow_above_75(const struct rhashtable *ht,
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| 183 | const struct bucket_table *tbl)
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| 184 | {
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| 185 |
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| 186 | return atomic_read(&ht->nelems) > (tbl->size / 4 * 3) &&
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| 187 | (!ht->p.max_size || tbl->size < ht->p.max_size);
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| 188 | }
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| 189 |
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| 190 | |
| 191 | * rht_shrink_below_30 - returns true if nelems < 0.3 * table-size
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| 192 | * @ht: hash table
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| 193 | * @tbl: current table
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| 194 |
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| 195 | static inline bool rht_shrink_below_30(const struct rhashtable *ht,
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| 196 | const struct bucket_table *tbl)
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| 197 | {
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| 198 |
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| 199 | return atomic_read(&ht->nelems) < (tbl->size * 3 / 10) &&
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| 200 | tbl->size > ht->p.min_size;
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| 201 | }
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| 202 |
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| 203 | |
| 204 | * rht_grow_above_100 - returns true if nelems > table-size
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| 205 | * @ht: hash table
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| 206 | * @tbl: current table
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| 207 |
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| 208 | static inline bool rht_grow_above_100(const struct rhashtable *ht,
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| 209 | const struct bucket_table *tbl)
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| 210 | {
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| 211 | return atomic_read(&ht->nelems) > tbl->size &&
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| 212 | (!ht->p.max_size || tbl->size < ht->p.max_size);
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| 213 | }
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| 214 |
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| 215 | |
| 216 | * rht_grow_above_max - returns true if table is above maximum
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| 217 | * @ht: hash table
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| 218 | * @tbl: current table
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| 219 |
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| 220 | static inline bool rht_grow_above_max(const struct rhashtable *ht,
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| 221 | const struct bucket_table *tbl)
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| 222 | {
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| 223 | return atomic_read(&ht->nelems) >= ht->max_elems;
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| 224 | }
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| 225 |
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| 226 | #ifdef CONFIG_PROVE_LOCKING
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| 227 | int lockdep_rht_mutex_is_held(struct rhashtable *ht);
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| 228 | int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash);
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| 229 | #else
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| 230 | static inline int lockdep_rht_mutex_is_held(struct rhashtable *ht)
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| 231 | {
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| 232 | return 1;
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| 233 | }
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| 234 |
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| 235 | static inline int lockdep_rht_bucket_is_held(const struct bucket_table *tbl,
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| 236 | u32 hash)
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| 237 | {
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| 238 | return 1;
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| 239 | }
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| 240 | #endif
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| 241 |
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| 242 | void *rhashtable_insert_slow(struct rhashtable *ht, const void *key,
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| 243 | struct rhash_head *obj);
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| 244 |
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| 245 | void rhashtable_walk_enter(struct rhashtable *ht,
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| 246 | struct rhashtable_iter *iter);
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| 247 | void rhashtable_walk_exit(struct rhashtable_iter *iter);
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| 248 | int rhashtable_walk_start_check(struct rhashtable_iter *iter) __acquires(RCU);
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| 249 |
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| 250 | static inline void rhashtable_walk_start(struct rhashtable_iter *iter)
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| 251 | {
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| 252 | (void)rhashtable_walk_start_check(iter);
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| 253 | }
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| 254 |
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| 255 | void *rhashtable_walk_next(struct rhashtable_iter *iter);
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| 256 | void *rhashtable_walk_peek(struct rhashtable_iter *iter);
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| 257 | void rhashtable_walk_stop(struct rhashtable_iter *iter) __releases(RCU);
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| 258 |
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| 259 | void rhashtable_free_and_destroy(struct rhashtable *ht,
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| 260 | void (*free_fn)(void *ptr, void *arg),
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| 261 | void *arg);
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| 262 | void rhashtable_destroy(struct rhashtable *ht);
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| 263 |
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| 264 | struct rhash_lock_head __rcu **rht_bucket_nested(
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| 265 | const struct bucket_table *tbl, unsigned int hash);
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| 266 | struct rhash_lock_head __rcu **__rht_bucket_nested(
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| 267 | const struct bucket_table *tbl, unsigned int hash);
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| 268 | struct rhash_lock_head __rcu **rht_bucket_nested_insert(
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| 269 | struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash);
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| 270 |
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| 271 | #define rht_dereference(p, ht) \
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| 272 | rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht))
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| 273 |
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| 274 | #define rht_dereference_rcu(p, ht) \
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| 275 | rcu_dereference_all_check(p, lockdep_rht_mutex_is_held(ht))
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| 276 |
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| 277 | #define rht_dereference_bucket(p, tbl, hash) \
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| 278 | rcu_dereference_protected(p, lockdep_rht_bucket_is_held(tbl, hash))
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| 279 |
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| 280 | #define rht_dereference_bucket_rcu(p, tbl, hash) \
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| 281 | rcu_dereference_all_check(p, lockdep_rht_bucket_is_held(tbl, hash))
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| 282 |
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| 283 | #define rht_entry(tpos, pos, member) \
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| 284 | ({ tpos = container_of(pos, typeof(*tpos), member); 1; })
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| 285 |
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| 286 | static inline struct rhash_lock_head __rcu *const *rht_bucket(
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| 287 | const struct bucket_table *tbl, unsigned int hash)
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| 288 | {
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| 289 | return unlikely(tbl->nest) ? rht_bucket_nested(tbl, hash) :
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| 290 | &tbl->buckets[hash];
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| 291 | }
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| 292 |
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| 293 | static inline struct rhash_lock_head __rcu **rht_bucket_var(
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| 294 | struct bucket_table *tbl, unsigned int hash)
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| 295 | {
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| 296 | return unlikely(tbl->nest) ? __rht_bucket_nested(tbl, hash) :
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| 297 | &tbl->buckets[hash];
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| 298 | }
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| 299 |
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| 300 | static inline struct rhash_lock_head __rcu **rht_bucket_insert(
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| 301 | struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash)
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| 302 | {
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| 303 | return unlikely(tbl->nest) ? rht_bucket_nested_insert(ht, tbl, hash) :
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| 304 | &tbl->buckets[hash];
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| 305 | }
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| 306 |
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| 307 | |
| 308 | * We lock a bucket by setting BIT(0) in the pointer - this is always
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| 309 | * zero in real pointers. The NULLS mark is never stored in the bucket,
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| 310 | * rather we store NULL if the bucket is empty.
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| 311 | * bit_spin_locks do not handle contention well, but the whole point
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| 312 | * of the hashtable design is to achieve minimum per-bucket contention.
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| 313 | * A nested hash table might not have a bucket pointer. In that case
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| 314 | * we cannot get a lock. For remove and replace the bucket cannot be
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| 315 | * interesting and doesn't need locking.
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| 316 | * For insert we allocate the bucket if this is the last bucket_table,
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| 317 | * and then take the lock.
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| 318 | * Sometimes we unlock a bucket by writing a new pointer there. In that
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| 319 | * case we don't need to unlock, but we do need to reset state such as
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| 320 | * local_bh. For that we have rht_assign_unlock(). As rcu_assign_pointer()
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| 321 | * provides the same release semantics that bit_spin_unlock() provides,
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| 322 | * this is safe.
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| 323 | * When we write to a bucket without unlocking, we use rht_assign_locked().
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| 324 |
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| 325 |
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| 326 | static inline unsigned long rht_lock(struct bucket_table *tbl,
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| 327 | struct rhash_lock_head __rcu **bkt)
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| 328 | {
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| 329 | unsigned long flags;
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| 330 |
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| 331 | local_irq_save(flags);
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| 332 | bit_spin_lock(0, (unsigned long *)bkt);
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| 333 | lock_map_acquire(&tbl->dep_map);
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| 334 | return flags;
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| 335 | }
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| 336 |
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| 337 | static inline unsigned long rht_lock_nested(struct bucket_table *tbl,
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| 338 | struct rhash_lock_head __rcu **bucket,
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| 339 | unsigned int subclass)
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| 340 | {
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| 341 | unsigned long flags;
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| 342 |
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| 343 | local_irq_save(flags);
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| 344 | bit_spin_lock(0, (unsigned long *)bucket);
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| 345 | lock_acquire_exclusive(&tbl->dep_map, subclass, 0, NULL, _THIS_IP_);
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| 346 | return flags;
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| 347 | }
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| 348 |
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| 349 | static inline void rht_unlock(struct bucket_table *tbl,
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| 350 | struct rhash_lock_head __rcu **bkt,
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| 351 | unsigned long flags)
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| 352 | {
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| 353 | lock_map_release(&tbl->dep_map);
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| 354 | bit_spin_unlock(0, (unsigned long *)bkt);
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| 355 | local_irq_restore(flags);
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| 356 | }
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| 357 |
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| 358 | static inline struct rhash_head *__rht_ptr(
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| 359 | struct rhash_lock_head *p, struct rhash_lock_head __rcu *const *bkt)
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| 360 | {
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| 361 | return (struct rhash_head *)
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| 362 | ((unsigned long)p & ~BIT(0) ?:
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| 363 | (unsigned long)RHT_NULLS_MARKER(bkt));
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| 364 | }
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| 365 |
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| 366 | |
| 367 | * Where 'bkt' is a bucket and might be locked:
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| 368 | * rht_ptr_rcu() dereferences that pointer and clears the lock bit.
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| 369 | * rht_ptr() dereferences in a context where the bucket is locked.
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| 370 | * rht_ptr_exclusive() dereferences in a context where exclusive
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| 371 | * access is guaranteed, such as when destroying the table.
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| 372 |
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| 373 | static inline struct rhash_head *rht_ptr_rcu(
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| 374 | struct rhash_lock_head __rcu *const *bkt)
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| 375 | {
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| 376 | return __rht_ptr(rcu_dereference_all(*bkt), bkt);
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| 377 | }
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| 378 |
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| 379 | static inline struct rhash_head *rht_ptr(
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| 380 | struct rhash_lock_head __rcu *const *bkt,
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| 381 | struct bucket_table *tbl,
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| 382 | unsigned int hash)
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| 383 | {
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| 384 | return __rht_ptr(rht_dereference_bucket(*bkt, tbl, hash), bkt);
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| 385 | }
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| 386 |
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| 387 | static inline struct rhash_head *rht_ptr_exclusive(
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| 388 | struct rhash_lock_head __rcu *const *bkt)
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| 389 | {
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| 390 | return __rht_ptr(rcu_dereference_protected(*bkt, 1), bkt);
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| 391 | }
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| 392 |
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| 393 | static inline void rht_assign_locked(struct rhash_lock_head __rcu **bkt,
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| 394 | struct rhash_head *obj)
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| 395 | {
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| 396 | if (rht_is_a_nulls(obj))
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| 397 | obj = NULL;
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| 398 | rcu_assign_pointer(*bkt, (void *)((unsigned long)obj | BIT(0)));
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| 399 | }
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| 400 |
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| 401 | static inline void rht_assign_unlock(struct bucket_table *tbl,
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| 402 | struct rhash_lock_head __rcu **bkt,
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| 403 | struct rhash_head *obj,
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| 404 | unsigned long flags)
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| 405 | {
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| 406 | if (rht_is_a_nulls(obj))
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| 407 | obj = NULL;
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| 408 | lock_map_release(&tbl->dep_map);
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| 409 | rcu_assign_pointer(*bkt, (void *)obj);
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| 410 | preempt_enable();
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| 411 | __release(bitlock);
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| 412 | local_irq_restore(flags);
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| 413 | }
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| 414 |
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| 415 | |
| 416 | * rht_for_each_from - iterate over hash chain from given head
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| 417 | * @pos: the &struct rhash_head to use as a loop cursor.
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| 418 | * @head: the &struct rhash_head to start from
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| 419 | * @tbl: the &struct bucket_table
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| 420 | * @hash: the hash value / bucket index
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| 421 |
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| 422 | #define rht_for_each_from(pos, head, tbl, hash) \
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| 423 | for (pos = head; \
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| 424 | !rht_is_a_nulls(pos); \
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| 425 | pos = rht_dereference_bucket((pos)->next, tbl, hash))
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| 426 |
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| 427 | |
| 428 | * rht_for_each - iterate over hash chain
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| 429 | * @pos: the &struct rhash_head to use as a loop cursor.
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| 430 | * @tbl: the &struct bucket_table
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| 431 | * @hash: the hash value / bucket index
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| 432 |
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| 433 | #define rht_for_each(pos, tbl, hash) \
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| 434 | rht_for_each_from(pos, rht_ptr(rht_bucket(tbl, hash), tbl, hash), \
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| 435 | tbl, hash)
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| 436 |
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| 437 | |
| 438 | * rht_for_each_entry_from - iterate over hash chain from given head
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| 439 | * @tpos: the type * to use as a loop cursor.
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| 440 | * @pos: the &struct rhash_head to use as a loop cursor.
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| 441 | * @head: the &struct rhash_head to start from
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| 442 | * @tbl: the &struct bucket_table
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| 443 | * @hash: the hash value / bucket index
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| 444 | * @member: name of the &struct rhash_head within the hashable struct.
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| 445 |
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| 446 | #define rht_for_each_entry_from(tpos, pos, head, tbl, hash, member) \
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| 447 | for (pos = head; \
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| 448 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
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| 449 | pos = rht_dereference_bucket((pos)->next, tbl, hash))
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| 450 |
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| 451 | |
| 452 | * rht_for_each_entry - iterate over hash chain of given type
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| 453 | * @tpos: the type * to use as a loop cursor.
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| 454 | * @pos: the &struct rhash_head to use as a loop cursor.
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| 455 | * @tbl: the &struct bucket_table
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| 456 | * @hash: the hash value / bucket index
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| 457 | * @member: name of the &struct rhash_head within the hashable struct.
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| 458 |
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| 459 | #define rht_for_each_entry(tpos, pos, tbl, hash, member) \
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| 460 | rht_for_each_entry_from(tpos, pos, \
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| 461 | rht_ptr(rht_bucket(tbl, hash), tbl, hash), \
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| 462 | tbl, hash, member)
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| 463 |
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| 464 | |
| 465 | * rht_for_each_entry_safe - safely iterate over hash chain of given type
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| 466 | * @tpos: the type * to use as a loop cursor.
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| 467 | * @pos: the &struct rhash_head to use as a loop cursor.
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| 468 | * @next: the &struct rhash_head to use as next in loop cursor.
|
| 469 | * @tbl: the &struct bucket_table
|
| 470 | * @hash: the hash value / bucket index
|
| 471 | * @member: name of the &struct rhash_head within the hashable struct.
|
| 472 | *
|
| 473 | * This hash chain list-traversal primitive allows for the looped code to
|
| 474 | * remove the loop cursor from the list.
|
| 475 |
|
| 476 | #define rht_for_each_entry_safe(tpos, pos, next, tbl, hash, member) \
|
| 477 | for (pos = rht_ptr(rht_bucket(tbl, hash), tbl, hash), \
|
| 478 | next = !rht_is_a_nulls(pos) ? \
|
| 479 | rht_dereference_bucket(pos->next, tbl, hash) : NULL; \
|
| 480 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
|
| 481 | pos = next, \
|
| 482 | next = !rht_is_a_nulls(pos) ? \
|
| 483 | rht_dereference_bucket(pos->next, tbl, hash) : NULL)
|
| 484 |
|
| 485 | |
| 486 | * rht_for_each_rcu_from - iterate over rcu hash chain from given head
|
| 487 | * @pos: the &struct rhash_head to use as a loop cursor.
|
| 488 | * @head: the &struct rhash_head to start from
|
| 489 | * @tbl: the &struct bucket_table
|
| 490 | * @hash: the hash value / bucket index
|
| 491 | *
|
| 492 | * This hash chain list-traversal primitive may safely run concurrently with
|
| 493 | * the _rcu mutation primitives such as rhashtable_insert() as long as the
|
| 494 | * traversal is guarded by rcu_read_lock().
|
| 495 |
|
| 496 | #define rht_for_each_rcu_from(pos, head, tbl, hash) \
|
| 497 | for (({barrier(); }), \
|
| 498 | pos = head; \
|
| 499 | !rht_is_a_nulls(pos); \
|
| 500 | pos = rcu_dereference_all(pos->next))
|
| 501 |
|
| 502 | |
| 503 | * rht_for_each_rcu - iterate over rcu hash chain
|
| 504 | * @pos: the &struct rhash_head to use as a loop cursor.
|
| 505 | * @tbl: the &struct bucket_table
|
| 506 | * @hash: the hash value / bucket index
|
| 507 | *
|
| 508 | * This hash chain list-traversal primitive may safely run concurrently with
|
| 509 | * the _rcu mutation primitives such as rhashtable_insert() as long as the
|
| 510 | * traversal is guarded by rcu_read_lock().
|
| 511 |
|
| 512 | #define rht_for_each_rcu(pos, tbl, hash) \
|
| 513 | for (({barrier(); }), \
|
| 514 | pos = rht_ptr_rcu(rht_bucket(tbl, hash)); \
|
| 515 | !rht_is_a_nulls(pos); \
|
| 516 | pos = rcu_dereference_all(pos->next))
|
| 517 |
|
| 518 | |
| 519 | * rht_for_each_entry_rcu_from - iterated over rcu hash chain from given head
|
| 520 | * @tpos: the type * to use as a loop cursor.
|
| 521 | * @pos: the &struct rhash_head to use as a loop cursor.
|
| 522 | * @head: the &struct rhash_head to start from
|
| 523 | * @tbl: the &struct bucket_table
|
| 524 | * @hash: the hash value / bucket index
|
| 525 | * @member: name of the &struct rhash_head within the hashable struct.
|
| 526 | *
|
| 527 | * This hash chain list-traversal primitive may safely run concurrently with
|
| 528 | * the _rcu mutation primitives such as rhashtable_insert() as long as the
|
| 529 | * traversal is guarded by rcu_read_lock().
|
| 530 |
|
| 531 | #define rht_for_each_entry_rcu_from(tpos, pos, head, tbl, hash, member) \
|
| 532 | for (({barrier(); }), \
|
| 533 | pos = head; \
|
| 534 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
|
| 535 | pos = rht_dereference_bucket_rcu(pos->next, tbl, hash))
|
| 536 |
|
| 537 | |
| 538 | * rht_for_each_entry_rcu - iterate over rcu hash chain of given type
|
| 539 | * @tpos: the type * to use as a loop cursor.
|
| 540 | * @pos: the &struct rhash_head to use as a loop cursor.
|
| 541 | * @tbl: the &struct bucket_table
|
| 542 | * @hash: the hash value / bucket index
|
| 543 | * @member: name of the &struct rhash_head within the hashable struct.
|
| 544 | *
|
| 545 | * This hash chain list-traversal primitive may safely run concurrently with
|
| 546 | * the _rcu mutation primitives such as rhashtable_insert() as long as the
|
| 547 | * traversal is guarded by rcu_read_lock().
|
| 548 |
|
| 549 | #define rht_for_each_entry_rcu(tpos, pos, tbl, hash, member) \
|
| 550 | rht_for_each_entry_rcu_from(tpos, pos, \
|
| 551 | rht_ptr_rcu(rht_bucket(tbl, hash)), \
|
| 552 | tbl, hash, member)
|
| 553 |
|
| 554 | |
| 555 | * rhl_for_each_rcu - iterate over rcu hash table list
|
| 556 | * @pos: the &struct rlist_head to use as a loop cursor.
|
| 557 | * @list: the head of the list
|
| 558 | *
|
| 559 | * This hash chain list-traversal primitive should be used on the
|
| 560 | * list returned by rhltable_lookup.
|
| 561 |
|
| 562 | #define rhl_for_each_rcu(pos, list) \
|
| 563 | for (pos = list; pos; pos = rcu_dereference_all(pos->next))
|
| 564 |
|
| 565 | |
| 566 | * rhl_for_each_entry_rcu - iterate over rcu hash table list of given type
|
| 567 | * @tpos: the type * to use as a loop cursor.
|
| 568 | * @pos: the &struct rlist_head to use as a loop cursor.
|
| 569 | * @list: the head of the list
|
| 570 | * @member: name of the &struct rlist_head within the hashable struct.
|
| 571 | *
|
| 572 | * This hash chain list-traversal primitive should be used on the
|
| 573 | * list returned by rhltable_lookup.
|
| 574 |
|
| 575 | #define rhl_for_each_entry_rcu(tpos, pos, list, member) \
|
| 576 | for (pos = list; pos && rht_entry(tpos, pos, member); \
|
| 577 | pos = rcu_dereference_all(pos->next))
|
| 578 |
|
| 579 | static inline int rhashtable_compare(struct rhashtable_compare_arg *arg,
|
| 580 | const void *obj)
|
| 581 | {
|
| 582 | struct rhashtable *ht = arg->ht;
|
| 583 | const char *ptr = obj;
|
| 584 |
|
| 585 | return memcmp(ptr + ht->p.key_offset, arg->key, ht->p.key_len);
|
| 586 | }
|
| 587 |
|
| 588 |
|
| 589 | static __always_inline struct rhash_head *__rhashtable_lookup(
|
| 590 | struct rhashtable *ht, const void *key,
|
| 591 | const struct rhashtable_params params)
|
| 592 | {
|
| 593 | struct rhashtable_compare_arg arg = {
|
| 594 | .ht = ht,
|
| 595 | .key = key,
|
| 596 | };
|
| 597 | struct rhash_lock_head __rcu *const *bkt;
|
| 598 | struct bucket_table *tbl;
|
| 599 | struct rhash_head *he;
|
| 600 | unsigned int hash;
|
| 601 |
|
| 602 | tbl = rht_dereference_rcu(ht->tbl, ht);
|
| 603 | restart:
|
| 604 | hash = rht_key_hashfn(ht, tbl, key, params);
|
| 605 | bkt = rht_bucket(tbl, hash);
|
| 606 | do {
|
| 607 | rht_for_each_rcu_from(he, rht_ptr_rcu(bkt), tbl, hash) {
|
| 608 | if (params.obj_cmpfn ?
|
| 609 | params.obj_cmpfn(&arg, rht_obj(ht, he)) :
|
| 610 | rhashtable_compare(&arg, rht_obj(ht, he)))
|
| 611 | continue;
|
| 612 | return he;
|
| 613 | }
|
| 614 | |
| 615 | * while we walk along it - better check and retry.
|
| 616 |
|
| 617 | } while (he != RHT_NULLS_MARKER(bkt));
|
| 618 |
|
| 619 |
|
| 620 | smp_rmb();
|
| 621 |
|
| 622 | tbl = rht_dereference_rcu(tbl->future_tbl, ht);
|
| 623 | if (unlikely(tbl))
|
| 624 | goto restart;
|
| 625 |
|
| 626 | return NULL;
|
| 627 | }
|
| 628 |
|
| 629 | |
| 630 | * rhashtable_lookup - search hash table
|
| 631 | * @ht: hash table
|
| 632 | * @key: the pointer to the key
|
| 633 | * @params: hash table parameters
|
| 634 | *
|
| 635 | * Computes the hash value for the key and traverses the bucket chain looking
|
| 636 | * for an entry with an identical key. The first matching entry is returned.
|
| 637 | *
|
| 638 | * This must only be called under the RCU read lock.
|
| 639 | *
|
| 640 | * Returns the first entry on which the compare function returned true.
|
| 641 |
|
| 642 | static __always_inline void *rhashtable_lookup(
|
| 643 | struct rhashtable *ht, const void *key,
|
| 644 | const struct rhashtable_params params)
|
| 645 | {
|
| 646 | struct rhash_head *he = __rhashtable_lookup(ht, key, params);
|
| 647 |
|
| 648 | return he ? rht_obj(ht, he) : NULL;
|
| 649 | }
|
| 650 |
|
| 651 | |
| 652 | * rhashtable_lookup_fast - search hash table, without RCU read lock
|
| 653 | * @ht: hash table
|
| 654 | * @key: the pointer to the key
|
| 655 | * @params: hash table parameters
|
| 656 | *
|
| 657 | * Computes the hash value for the key and traverses the bucket chain looking
|
| 658 | * for an entry with an identical key. The first matching entry is returned.
|
| 659 | *
|
| 660 | * Only use this function when you have other mechanisms guaranteeing
|
| 661 | * that the object won't go away after the RCU read lock is released.
|
| 662 | *
|
| 663 | * Returns the first entry on which the compare function returned true.
|
| 664 |
|
| 665 | static __always_inline void *rhashtable_lookup_fast(
|
| 666 | struct rhashtable *ht, const void *key,
|
| 667 | const struct rhashtable_params params)
|
| 668 | {
|
| 669 | void *obj;
|
| 670 |
|
| 671 | rcu_read_lock();
|
| 672 | obj = rhashtable_lookup(ht, key, params);
|
| 673 | rcu_read_unlock();
|
| 674 |
|
| 675 | return obj;
|
| 676 | }
|
| 677 |
|
| 678 | |
| 679 | * rhltable_lookup - search hash list table
|
| 680 | * @hlt: hash table
|
| 681 | * @key: the pointer to the key
|
| 682 | * @params: hash table parameters
|
| 683 | *
|
| 684 | * Computes the hash value for the key and traverses the bucket chain looking
|
| 685 | * for an entry with an identical key. All matching entries are returned
|
| 686 | * in a list.
|
| 687 | *
|
| 688 | * This must only be called under the RCU read lock.
|
| 689 | *
|
| 690 | * Returns the list of entries that match the given key.
|
| 691 |
|
| 692 | static __always_inline struct rhlist_head *rhltable_lookup(
|
| 693 | struct rhltable *hlt, const void *key,
|
| 694 | const struct rhashtable_params params)
|
| 695 | {
|
| 696 | struct rhash_head *he = __rhashtable_lookup(&hlt->ht, key, params);
|
| 697 |
|
| 698 | return he ? container_of(he, struct rhlist_head, rhead) : NULL;
|
| 699 | }
|
| 700 |
|
| 701 | |
| 702 | * function returns the existing element already in hashes if there is a clash,
|
| 703 | * otherwise it returns an error via ERR_PTR().
|
| 704 |
|
| 705 | static __always_inline void *__rhashtable_insert_fast(
|
| 706 | struct rhashtable *ht, const void *key, struct rhash_head *obj,
|
| 707 | const struct rhashtable_params params, bool rhlist)
|
| 708 | {
|
| 709 | struct rhashtable_compare_arg arg = {
|
| 710 | .ht = ht,
|
| 711 | .key = key,
|
| 712 | };
|
| 713 | struct rhash_lock_head __rcu **bkt;
|
| 714 | struct rhash_head __rcu **pprev;
|
| 715 | struct bucket_table *tbl;
|
| 716 | struct rhash_head *head;
|
| 717 | unsigned long flags;
|
| 718 | unsigned int hash;
|
| 719 | int elasticity;
|
| 720 | void *data;
|
| 721 |
|
| 722 | rcu_read_lock();
|
| 723 |
|
| 724 | tbl = rht_dereference_rcu(ht->tbl, ht);
|
| 725 | hash = rht_head_hashfn(ht, tbl, obj, params);
|
| 726 | elasticity = RHT_ELASTICITY;
|
| 727 | bkt = rht_bucket_insert(ht, tbl, hash);
|
| 728 | data = ERR_PTR(-ENOMEM);
|
| 729 | if (!bkt)
|
| 730 | goto out;
|
| 731 | pprev = NULL;
|
| 732 | flags = rht_lock(tbl, bkt);
|
| 733 |
|
| 734 | if (unlikely(rcu_access_pointer(tbl->future_tbl))) {
|
| 735 | slow_path:
|
| 736 | rht_unlock(tbl, bkt, flags);
|
| 737 | rcu_read_unlock();
|
| 738 | return rhashtable_insert_slow(ht, key, obj);
|
| 739 | }
|
| 740 |
|
| 741 | rht_for_each_from(head, rht_ptr(bkt, tbl, hash), tbl, hash) {
|
| 742 | struct rhlist_head *plist;
|
| 743 | struct rhlist_head *list;
|
| 744 |
|
| 745 | elasticity--;
|
| 746 | if (!key ||
|
| 747 | (params.obj_cmpfn ?
|
| 748 | params.obj_cmpfn(&arg, rht_obj(ht, head)) :
|
| 749 | rhashtable_compare(&arg, rht_obj(ht, head)))) {
|
| 750 | pprev = &head->next;
|
| 751 | continue;
|
| 752 | }
|
| 753 |
|
| 754 | data = rht_obj(ht, head);
|
| 755 |
|
| 756 | if (!rhlist)
|
| 757 | goto out_unlock;
|
| 758 |
|
| 759 |
|
| 760 | list = container_of(obj, struct rhlist_head, rhead);
|
| 761 | plist = container_of(head, struct rhlist_head, rhead);
|
| 762 |
|
| 763 | RCU_INIT_POINTER(list->next, plist);
|
| 764 | head = rht_dereference_bucket(head->next, tbl, hash);
|
| 765 | RCU_INIT_POINTER(list->rhead.next, head);
|
| 766 | if (pprev) {
|
| 767 | rcu_assign_pointer(*pprev, obj);
|
| 768 | rht_unlock(tbl, bkt, flags);
|
| 769 | } else
|
| 770 | rht_assign_unlock(tbl, bkt, obj, flags);
|
| 771 | data = NULL;
|
| 772 | goto out;
|
| 773 | }
|
| 774 |
|
| 775 | if (elasticity <= 0)
|
| 776 | goto slow_path;
|
| 777 |
|
| 778 | data = ERR_PTR(-E2BIG);
|
| 779 | if (unlikely(rht_grow_above_max(ht, tbl)))
|
| 780 | goto out_unlock;
|
| 781 |
|
| 782 | if (unlikely(rht_grow_above_100(ht, tbl)))
|
| 783 | goto slow_path;
|
| 784 |
|
| 785 |
|
| 786 | head = rht_ptr(bkt, tbl, hash);
|
| 787 |
|
| 788 | RCU_INIT_POINTER(obj->next, head);
|
| 789 | if (rhlist) {
|
| 790 | struct rhlist_head *list;
|
| 791 |
|
| 792 | list = container_of(obj, struct rhlist_head, rhead);
|
| 793 | RCU_INIT_POINTER(list->next, NULL);
|
| 794 | }
|
| 795 |
|
| 796 | atomic_inc(&ht->nelems);
|
| 797 | rht_assign_unlock(tbl, bkt, obj, flags);
|
| 798 |
|
| 799 | if (rht_grow_above_75(ht, tbl))
|
| 800 | schedule_work(&ht->run_work);
|
| 801 |
|
| 802 | data = NULL;
|
| 803 | out:
|
| 804 | rcu_read_unlock();
|
| 805 |
|
| 806 | return data;
|
| 807 |
|
| 808 | out_unlock:
|
| 809 | rht_unlock(tbl, bkt, flags);
|
| 810 | goto out;
|
| 811 | }
|
| 812 |
|
| 813 | |
| 814 | * rhashtable_insert_fast - insert object into hash table
|
| 815 | * @ht: hash table
|
| 816 | * @obj: pointer to hash head inside object
|
| 817 | * @params: hash table parameters
|
| 818 | *
|
| 819 | * Will take the per bucket bitlock to protect against mutual mutations
|
| 820 | * on the same bucket. Multiple insertions may occur in parallel unless
|
| 821 | * they map to the same bucket.
|
| 822 | *
|
| 823 | * It is safe to call this function from atomic context.
|
| 824 | *
|
| 825 | * Will trigger an automatic deferred table resizing if residency in the
|
| 826 | * table grows beyond 70%.
|
| 827 |
|
| 828 | static __always_inline int rhashtable_insert_fast(
|
| 829 | struct rhashtable *ht, struct rhash_head *obj,
|
| 830 | const struct rhashtable_params params)
|
| 831 | {
|
| 832 | void *ret;
|
| 833 |
|
| 834 | ret = __rhashtable_insert_fast(ht, NULL, obj, params, false);
|
| 835 | if (IS_ERR(ret))
|
| 836 | return PTR_ERR(ret);
|
| 837 |
|
| 838 | return ret == NULL ? 0 : -EEXIST;
|
| 839 | }
|
| 840 |
|
| 841 | |
| 842 | * rhltable_insert_key - insert object into hash list table
|
| 843 | * @hlt: hash list table
|
| 844 | * @key: the pointer to the key
|
| 845 | * @list: pointer to hash list head inside object
|
| 846 | * @params: hash table parameters
|
| 847 | *
|
| 848 | * Will take the per bucket bitlock to protect against mutual mutations
|
| 849 | * on the same bucket. Multiple insertions may occur in parallel unless
|
| 850 | * they map to the same bucket.
|
| 851 | *
|
| 852 | * It is safe to call this function from atomic context.
|
| 853 | *
|
| 854 | * Will trigger an automatic deferred table resizing if residency in the
|
| 855 | * table grows beyond 70%.
|
| 856 |
|
| 857 | static __always_inline int rhltable_insert_key(
|
| 858 | struct rhltable *hlt, const void *key, struct rhlist_head *list,
|
| 859 | const struct rhashtable_params params)
|
| 860 | {
|
| 861 | return PTR_ERR(__rhashtable_insert_fast(&hlt->ht, key, &list->rhead,
|
| 862 | params, true));
|
| 863 | }
|
| 864 |
|
| 865 | |
| 866 | * rhltable_insert - insert object into hash list table
|
| 867 | * @hlt: hash list table
|
| 868 | * @list: pointer to hash list head inside object
|
| 869 | * @params: hash table parameters
|
| 870 | *
|
| 871 | * Will take the per bucket bitlock to protect against mutual mutations
|
| 872 | * on the same bucket. Multiple insertions may occur in parallel unless
|
| 873 | * they map to the same bucket.
|
| 874 | *
|
| 875 | * It is safe to call this function from atomic context.
|
| 876 | *
|
| 877 | * Will trigger an automatic deferred table resizing if residency in the
|
| 878 | * table grows beyond 70%.
|
| 879 |
|
| 880 | static __always_inline int rhltable_insert(
|
| 881 | struct rhltable *hlt, struct rhlist_head *list,
|
| 882 | const struct rhashtable_params params)
|
| 883 | {
|
| 884 | const char *key = rht_obj(&hlt->ht, &list->rhead);
|
| 885 |
|
| 886 | key += params.key_offset;
|
| 887 |
|
| 888 | return rhltable_insert_key(hlt, key, list, params);
|
| 889 | }
|
| 890 |
|
| 891 | |
| 892 | * rhashtable_lookup_insert_fast - lookup and insert object into hash table
|
| 893 | * @ht: hash table
|
| 894 | * @obj: pointer to hash head inside object
|
| 895 | * @params: hash table parameters
|
| 896 | *
|
| 897 | * This lookup function may only be used for fixed key hash table (key_len
|
| 898 | * parameter set). It will BUG() if used inappropriately.
|
| 899 | *
|
| 900 | * It is safe to call this function from atomic context.
|
| 901 | *
|
| 902 | * Will trigger an automatic deferred table resizing if residency in the
|
| 903 | * table grows beyond 70%.
|
| 904 |
|
| 905 | static __always_inline int rhashtable_lookup_insert_fast(
|
| 906 | struct rhashtable *ht, struct rhash_head *obj,
|
| 907 | const struct rhashtable_params params)
|
| 908 | {
|
| 909 | const char *key = rht_obj(ht, obj);
|
| 910 | void *ret;
|
| 911 |
|
| 912 | BUG_ON(ht->p.obj_hashfn);
|
| 913 |
|
| 914 | ret = __rhashtable_insert_fast(ht, key + ht->p.key_offset, obj, params,
|
| 915 | false);
|
| 916 | if (IS_ERR(ret))
|
| 917 | return PTR_ERR(ret);
|
| 918 |
|
| 919 | return ret == NULL ? 0 : -EEXIST;
|
| 920 | }
|
| 921 |
|
| 922 | |
| 923 | * rhashtable_lookup_get_insert_fast - lookup and insert object into hash table
|
| 924 | * @ht: hash table
|
| 925 | * @obj: pointer to hash head inside object
|
| 926 | * @params: hash table parameters
|
| 927 | *
|
| 928 | * Just like rhashtable_lookup_insert_fast(), but this function returns the
|
| 929 | * object if it exists, NULL if it did not and the insertion was successful,
|
| 930 | * and an ERR_PTR otherwise.
|
| 931 |
|
| 932 | static __always_inline void *rhashtable_lookup_get_insert_fast(
|
| 933 | struct rhashtable *ht, struct rhash_head *obj,
|
| 934 | const struct rhashtable_params params)
|
| 935 | {
|
| 936 | const char *key = rht_obj(ht, obj);
|
| 937 |
|
| 938 | BUG_ON(ht->p.obj_hashfn);
|
| 939 |
|
| 940 | return __rhashtable_insert_fast(ht, key + ht->p.key_offset, obj, params,
|
| 941 | false);
|
| 942 | }
|
| 943 |
|
| 944 | |
| 945 | * rhashtable_lookup_insert_key - search and insert object to hash table
|
| 946 | * with explicit key
|
| 947 | * @ht: hash table
|
| 948 | * @key: key
|
| 949 | * @obj: pointer to hash head inside object
|
| 950 | * @params: hash table parameters
|
| 951 | *
|
| 952 | * Lookups may occur in parallel with hashtable mutations and resizing.
|
| 953 | *
|
| 954 | * Will trigger an automatic deferred table resizing if residency in the
|
| 955 | * table grows beyond 70%.
|
| 956 | *
|
| 957 | * Returns zero on success.
|
| 958 |
|
| 959 | static __always_inline int rhashtable_lookup_insert_key(
|
| 960 | struct rhashtable *ht, const void *key, struct rhash_head *obj,
|
| 961 | const struct rhashtable_params params)
|
| 962 | {
|
| 963 | void *ret;
|
| 964 |
|
| 965 | BUG_ON(!ht->p.obj_hashfn || !key);
|
| 966 |
|
| 967 | ret = __rhashtable_insert_fast(ht, key, obj, params, false);
|
| 968 | if (IS_ERR(ret))
|
| 969 | return PTR_ERR(ret);
|
| 970 |
|
| 971 | return ret == NULL ? 0 : -EEXIST;
|
| 972 | }
|
| 973 |
|
| 974 | |
| 975 | * rhashtable_lookup_get_insert_key - lookup and insert object into hash table
|
| 976 | * @ht: hash table
|
| 977 | * @key: key
|
| 978 | * @obj: pointer to hash head inside object
|
| 979 | * @params: hash table parameters
|
| 980 | *
|
| 981 | * Just like rhashtable_lookup_insert_key(), but this function returns the
|
| 982 | * object if it exists, NULL if it does not and the insertion was successful,
|
| 983 | * and an ERR_PTR otherwise.
|
| 984 |
|
| 985 | static __always_inline void *rhashtable_lookup_get_insert_key(
|
| 986 | struct rhashtable *ht, const void *key, struct rhash_head *obj,
|
| 987 | const struct rhashtable_params params)
|
| 988 | {
|
| 989 | BUG_ON(!ht->p.obj_hashfn || !key);
|
| 990 |
|
| 991 | return __rhashtable_insert_fast(ht, key, obj, params, false);
|
| 992 | }
|
| 993 |
|
| 994 |
|
| 995 | static __always_inline int __rhashtable_remove_fast_one(
|
| 996 | struct rhashtable *ht, struct bucket_table *tbl,
|
| 997 | struct rhash_head *obj, const struct rhashtable_params params,
|
| 998 | bool rhlist)
|
| 999 | {
|
| 1000 | struct rhash_lock_head __rcu **bkt;
|
| 1001 | struct rhash_head __rcu **pprev;
|
| 1002 | struct rhash_head *he;
|
| 1003 | unsigned long flags;
|
| 1004 | unsigned int hash;
|
| 1005 | int err = -ENOENT;
|
| 1006 |
|
| 1007 | hash = rht_head_hashfn(ht, tbl, obj, params);
|
| 1008 | bkt = rht_bucket_var(tbl, hash);
|
| 1009 | if (!bkt)
|
| 1010 | return -ENOENT;
|
| 1011 | pprev = NULL;
|
| 1012 | flags = rht_lock(tbl, bkt);
|
| 1013 |
|
| 1014 | rht_for_each_from(he, rht_ptr(bkt, tbl, hash), tbl, hash) {
|
| 1015 | struct rhlist_head *list;
|
| 1016 |
|
| 1017 | list = container_of(he, struct rhlist_head, rhead);
|
| 1018 |
|
| 1019 | if (he != obj) {
|
| 1020 | struct rhlist_head __rcu **lpprev;
|
| 1021 |
|
| 1022 | pprev = &he->next;
|
| 1023 |
|
| 1024 | if (!rhlist)
|
| 1025 | continue;
|
| 1026 |
|
| 1027 | do {
|
| 1028 | lpprev = &list->next;
|
| 1029 | list = rht_dereference_bucket(list->next,
|
| 1030 | tbl, hash);
|
| 1031 | } while (list && obj != &list->rhead);
|
| 1032 |
|
| 1033 | if (!list)
|
| 1034 | continue;
|
| 1035 |
|
| 1036 | list = rht_dereference_bucket(list->next, tbl, hash);
|
| 1037 | RCU_INIT_POINTER(*lpprev, list);
|
| 1038 | err = 0;
|
| 1039 | break;
|
| 1040 | }
|
| 1041 |
|
| 1042 | obj = rht_dereference_bucket(obj->next, tbl, hash);
|
| 1043 | err = 1;
|
| 1044 |
|
| 1045 | if (rhlist) {
|
| 1046 | list = rht_dereference_bucket(list->next, tbl, hash);
|
| 1047 | if (list) {
|
| 1048 | RCU_INIT_POINTER(list->rhead.next, obj);
|
| 1049 | obj = &list->rhead;
|
| 1050 | err = 0;
|
| 1051 | }
|
| 1052 | }
|
| 1053 |
|
| 1054 | if (pprev) {
|
| 1055 | rcu_assign_pointer(*pprev, obj);
|
| 1056 | rht_unlock(tbl, bkt, flags);
|
| 1057 | } else {
|
| 1058 | rht_assign_unlock(tbl, bkt, obj, flags);
|
| 1059 | }
|
| 1060 | goto unlocked;
|
| 1061 | }
|
| 1062 |
|
| 1063 | rht_unlock(tbl, bkt, flags);
|
| 1064 | unlocked:
|
| 1065 | if (err > 0) {
|
| 1066 | atomic_dec(&ht->nelems);
|
| 1067 | if (unlikely(ht->p.automatic_shrinking &&
|
| 1068 | rht_shrink_below_30(ht, tbl)))
|
| 1069 | schedule_work(&ht->run_work);
|
| 1070 | err = 0;
|
| 1071 | }
|
| 1072 |
|
| 1073 | return err;
|
| 1074 | }
|
| 1075 |
|
| 1076 |
|
| 1077 | static __always_inline int __rhashtable_remove_fast(
|
| 1078 | struct rhashtable *ht, struct rhash_head *obj,
|
| 1079 | const struct rhashtable_params params, bool rhlist)
|
| 1080 | {
|
| 1081 | struct bucket_table *tbl;
|
| 1082 | int err;
|
| 1083 |
|
| 1084 | rcu_read_lock();
|
| 1085 |
|
| 1086 | tbl = rht_dereference_rcu(ht->tbl, ht);
|
| 1087 |
|
| 1088 | |
| 1089 | * lock in old_tbl, if we find that future_tbl is not yet
|
| 1090 | * visible then that guarantees the entry to still be in
|
| 1091 | * the old tbl if it exists.
|
| 1092 |
|
| 1093 | while ((err = __rhashtable_remove_fast_one(ht, tbl, obj, params,
|
| 1094 | rhlist)) &&
|
| 1095 | (tbl = rht_dereference_rcu(tbl->future_tbl, ht)))
|
| 1096 | ;
|
| 1097 |
|
| 1098 | rcu_read_unlock();
|
| 1099 |
|
| 1100 | return err;
|
| 1101 | }
|
| 1102 |
|
| 1103 | |
| 1104 | * rhashtable_remove_fast - remove object from hash table
|
| 1105 | * @ht: hash table
|
| 1106 | * @obj: pointer to hash head inside object
|
| 1107 | * @params: hash table parameters
|
| 1108 | *
|
| 1109 | * Since the hash chain is single linked, the removal operation needs to
|
| 1110 | * walk the bucket chain upon removal. The removal operation is thus
|
| 1111 | * considerable slow if the hash table is not correctly sized.
|
| 1112 | *
|
| 1113 | * Will automatically shrink the table if permitted when residency drops
|
| 1114 | * below 30%.
|
| 1115 | *
|
| 1116 | * Returns zero on success, -ENOENT if the entry could not be found.
|
| 1117 |
|
| 1118 | static __always_inline int rhashtable_remove_fast(
|
| 1119 | struct rhashtable *ht, struct rhash_head *obj,
|
| 1120 | const struct rhashtable_params params)
|
| 1121 | {
|
| 1122 | return __rhashtable_remove_fast(ht, obj, params, false);
|
| 1123 | }
|
| 1124 |
|
| 1125 | |
| 1126 | * rhltable_remove - remove object from hash list table
|
| 1127 | * @hlt: hash list table
|
| 1128 | * @list: pointer to hash list head inside object
|
| 1129 | * @params: hash table parameters
|
| 1130 | *
|
| 1131 | * Since the hash chain is single linked, the removal operation needs to
|
| 1132 | * walk the bucket chain upon removal. The removal operation is thus
|
| 1133 | * considerably slower if the hash table is not correctly sized.
|
| 1134 | *
|
| 1135 | * Will automatically shrink the table if permitted when residency drops
|
| 1136 | * below 30%
|
| 1137 | *
|
| 1138 | * Returns zero on success, -ENOENT if the entry could not be found.
|
| 1139 |
|
| 1140 | static __always_inline int rhltable_remove(
|
| 1141 | struct rhltable *hlt, struct rhlist_head *list,
|
| 1142 | const struct rhashtable_params params)
|
| 1143 | {
|
| 1144 | return __rhashtable_remove_fast(&hlt->ht, &list->rhead, params, true);
|
| 1145 | }
|
| 1146 |
|
| 1147 |
|
| 1148 | static __always_inline int __rhashtable_replace_fast(
|
| 1149 | struct rhashtable *ht, struct bucket_table *tbl,
|
| 1150 | struct rhash_head *obj_old, struct rhash_head *obj_new,
|
| 1151 | const struct rhashtable_params params)
|
| 1152 | {
|
| 1153 | struct rhash_lock_head __rcu **bkt;
|
| 1154 | struct rhash_head __rcu **pprev;
|
| 1155 | struct rhash_head *he;
|
| 1156 | unsigned long flags;
|
| 1157 | unsigned int hash;
|
| 1158 | int err = -ENOENT;
|
| 1159 |
|
| 1160 | |
| 1161 | * (which should mean identifiers are the same).
|
| 1162 |
|
| 1163 | hash = rht_head_hashfn(ht, tbl, obj_old, params);
|
| 1164 | if (hash != rht_head_hashfn(ht, tbl, obj_new, params))
|
| 1165 | return -EINVAL;
|
| 1166 |
|
| 1167 | bkt = rht_bucket_var(tbl, hash);
|
| 1168 | if (!bkt)
|
| 1169 | return -ENOENT;
|
| 1170 |
|
| 1171 | pprev = NULL;
|
| 1172 | flags = rht_lock(tbl, bkt);
|
| 1173 |
|
| 1174 | rht_for_each_from(he, rht_ptr(bkt, tbl, hash), tbl, hash) {
|
| 1175 | if (he != obj_old) {
|
| 1176 | pprev = &he->next;
|
| 1177 | continue;
|
| 1178 | }
|
| 1179 |
|
| 1180 | rcu_assign_pointer(obj_new->next, obj_old->next);
|
| 1181 | if (pprev) {
|
| 1182 | rcu_assign_pointer(*pprev, obj_new);
|
| 1183 | rht_unlock(tbl, bkt, flags);
|
| 1184 | } else {
|
| 1185 | rht_assign_unlock(tbl, bkt, obj_new, flags);
|
| 1186 | }
|
| 1187 | err = 0;
|
| 1188 | goto unlocked;
|
| 1189 | }
|
| 1190 |
|
| 1191 | rht_unlock(tbl, bkt, flags);
|
| 1192 |
|
| 1193 | unlocked:
|
| 1194 | return err;
|
| 1195 | }
|
| 1196 |
|
| 1197 | |
| 1198 | * rhashtable_replace_fast - replace an object in hash table
|
| 1199 | * @ht: hash table
|
| 1200 | * @obj_old: pointer to hash head inside object being replaced
|
| 1201 | * @obj_new: pointer to hash head inside object which is new
|
| 1202 | * @params: hash table parameters
|
| 1203 | *
|
| 1204 | * Replacing an object doesn't affect the number of elements in the hash table
|
| 1205 | * or bucket, so we don't need to worry about shrinking or expanding the
|
| 1206 | * table here.
|
| 1207 | *
|
| 1208 | * Returns zero on success, -ENOENT if the entry could not be found,
|
| 1209 | * -EINVAL if hash is not the same for the old and new objects.
|
| 1210 |
|
| 1211 | static __always_inline int rhashtable_replace_fast(
|
| 1212 | struct rhashtable *ht, struct rhash_head *obj_old,
|
| 1213 | struct rhash_head *obj_new,
|
| 1214 | const struct rhashtable_params params)
|
| 1215 | {
|
| 1216 | struct bucket_table *tbl;
|
| 1217 | int err;
|
| 1218 |
|
| 1219 | rcu_read_lock();
|
| 1220 |
|
| 1221 | tbl = rht_dereference_rcu(ht->tbl, ht);
|
| 1222 |
|
| 1223 | |
| 1224 | * lock in old_tbl, if we find that future_tbl is not yet
|
| 1225 | * visible then that guarantees the entry to still be in
|
| 1226 | * the old tbl if it exists.
|
| 1227 |
|
| 1228 | while ((err = __rhashtable_replace_fast(ht, tbl, obj_old,
|
| 1229 | obj_new, params)) &&
|
| 1230 | (tbl = rht_dereference_rcu(tbl->future_tbl, ht)))
|
| 1231 | ;
|
| 1232 |
|
| 1233 | rcu_read_unlock();
|
| 1234 |
|
| 1235 | return err;
|
| 1236 | }
|
| 1237 |
|
| 1238 | |
| 1239 | * rhltable_walk_enter - Initialise an iterator
|
| 1240 | * @hlt: Table to walk over
|
| 1241 | * @iter: Hash table Iterator
|
| 1242 | *
|
| 1243 | * This function prepares a hash table walk.
|
| 1244 | *
|
| 1245 | * Note that if you restart a walk after rhashtable_walk_stop you
|
| 1246 | * may see the same object twice. Also, you may miss objects if
|
| 1247 | * there are removals in between rhashtable_walk_stop and the next
|
| 1248 | * call to rhashtable_walk_start.
|
| 1249 | *
|
| 1250 | * For a completely stable walk you should construct your own data
|
| 1251 | * structure outside the hash table.
|
| 1252 | *
|
| 1253 | * This function may be called from any process context, including
|
| 1254 | * non-preemptable context, but cannot be called from softirq or
|
| 1255 | * hardirq context.
|
| 1256 | *
|
| 1257 | * You must call rhashtable_walk_exit after this function returns.
|
| 1258 |
|
| 1259 | static inline void rhltable_walk_enter(struct rhltable *hlt,
|
| 1260 | struct rhashtable_iter *iter)
|
| 1261 | {
|
| 1262 | rhashtable_walk_enter(&hlt->ht, iter);
|
| 1263 | }
|
| 1264 |
|
| 1265 | |
| 1266 | * rhltable_free_and_destroy - free elements and destroy hash list table
|
| 1267 | * @hlt: the hash list table to destroy
|
| 1268 | * @free_fn: callback to release resources of element
|
| 1269 | * @arg: pointer passed to free_fn
|
| 1270 | *
|
| 1271 | * See documentation for rhashtable_free_and_destroy.
|
| 1272 |
|
| 1273 | static inline void rhltable_free_and_destroy(struct rhltable *hlt,
|
| 1274 | void (*free_fn)(void *ptr,
|
| 1275 | void *arg),
|
| 1276 | void *arg)
|
| 1277 | {
|
| 1278 | rhashtable_free_and_destroy(&hlt->ht, free_fn, arg);
|
| 1279 | }
|
| 1280 |
|
| 1281 | static inline void rhltable_destroy(struct rhltable *hlt)
|
| 1282 | {
|
| 1283 | rhltable_free_and_destroy(hlt, NULL, NULL);
|
| 1284 | }
|
| 1285 |
|
| 1286 | #endif
|