Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 1 | /* |
| 2 | * Resizable, Scalable, Concurrent Hash Table |
| 3 | * |
Herbert Xu | dc0ee26 | 2015-03-20 21:57:06 +1100 | [diff] [blame] | 4 | * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au> |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 5 | * Copyright (c) 2014 Thomas Graf <tgraf@suug.ch> |
| 6 | * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net> |
| 7 | * |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 8 | * Code partially derived from nft_hash |
Herbert Xu | dc0ee26 | 2015-03-20 21:57:06 +1100 | [diff] [blame] | 9 | * Rewritten with rehash code from br_multicast plus single list |
| 10 | * pointer as suggested by Josh Triplett |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 11 | * |
| 12 | * This program is free software; you can redistribute it and/or modify |
| 13 | * it under the terms of the GNU General Public License version 2 as |
| 14 | * published by the Free Software Foundation. |
| 15 | */ |
| 16 | |
| 17 | #ifndef _LINUX_RHASHTABLE_H |
| 18 | #define _LINUX_RHASHTABLE_H |
| 19 | |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 20 | #include <linux/compiler.h> |
Herbert Xu | 6626af6 | 2015-03-20 18:18:45 -0400 | [diff] [blame] | 21 | #include <linux/errno.h> |
Herbert Xu | 31ccde2 | 2015-03-24 00:50:21 +1100 | [diff] [blame] | 22 | #include <linux/jhash.h> |
Thomas Graf | f89bd6f | 2015-01-02 23:00:21 +0100 | [diff] [blame] | 23 | #include <linux/list_nulls.h> |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 24 | #include <linux/workqueue.h> |
Ying Xue | 86b35b6 | 2015-01-04 15:25:09 +0800 | [diff] [blame] | 25 | #include <linux/mutex.h> |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 26 | #include <linux/rcupdate.h> |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 27 | |
Thomas Graf | f89bd6f | 2015-01-02 23:00:21 +0100 | [diff] [blame] | 28 | /* |
| 29 | * The end of the chain is marked with a special nulls marks which has |
| 30 | * the following format: |
| 31 | * |
| 32 | * +-------+-----------------------------------------------------+-+ |
| 33 | * | Base | Hash |1| |
| 34 | * +-------+-----------------------------------------------------+-+ |
| 35 | * |
| 36 | * Base (4 bits) : Reserved to distinguish between multiple tables. |
| 37 | * Specified via &struct rhashtable_params.nulls_base. |
| 38 | * Hash (27 bits): Full hash (unmasked) of first element added to bucket |
| 39 | * 1 (1 bit) : Nulls marker (always set) |
| 40 | * |
| 41 | * The remaining bits of the next pointer remain unused for now. |
| 42 | */ |
| 43 | #define RHT_BASE_BITS 4 |
| 44 | #define RHT_HASH_BITS 27 |
| 45 | #define RHT_BASE_SHIFT RHT_HASH_BITS |
| 46 | |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 47 | /* Base bits plus 1 bit for nulls marker */ |
| 48 | #define RHT_HASH_RESERVED_SPACE (RHT_BASE_BITS + 1) |
| 49 | |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 50 | struct rhash_head { |
Thomas Graf | 5300fdc | 2014-08-13 16:38:29 +0200 | [diff] [blame] | 51 | struct rhash_head __rcu *next; |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 52 | }; |
| 53 | |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 54 | /** |
| 55 | * struct bucket_table - Table of hash buckets |
| 56 | * @size: Number of hash buckets |
Herbert Xu | 63d512d | 2015-03-14 13:57:24 +1100 | [diff] [blame] | 57 | * @rehash: Current bucket being rehashed |
Herbert Xu | 988dfbd | 2015-03-10 09:27:55 +1100 | [diff] [blame] | 58 | * @hash_rnd: Random seed to fold into hash |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 59 | * @locks_mask: Mask to apply before accessing locks[] |
| 60 | * @locks: Array of spinlocks protecting individual buckets |
Herbert Xu | eddee5ba | 2015-03-14 13:57:20 +1100 | [diff] [blame] | 61 | * @walkers: List of active walkers |
Herbert Xu | 9d901bc | 2015-03-14 13:57:23 +1100 | [diff] [blame] | 62 | * @rcu: RCU structure for freeing the table |
Herbert Xu | c4db884 | 2015-03-14 13:57:25 +1100 | [diff] [blame] | 63 | * @future_tbl: Table under construction during rehashing |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 64 | * @buckets: size * hash buckets |
| 65 | */ |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 66 | struct bucket_table { |
Herbert Xu | 63d512d | 2015-03-14 13:57:24 +1100 | [diff] [blame] | 67 | unsigned int size; |
| 68 | unsigned int rehash; |
Herbert Xu | 988dfbd | 2015-03-10 09:27:55 +1100 | [diff] [blame] | 69 | u32 hash_rnd; |
Eric Dumazet | b9ebafb | 2015-02-20 06:48:57 -0800 | [diff] [blame] | 70 | unsigned int locks_mask; |
| 71 | spinlock_t *locks; |
Herbert Xu | eddee5ba | 2015-03-14 13:57:20 +1100 | [diff] [blame] | 72 | struct list_head walkers; |
Herbert Xu | 9d901bc | 2015-03-14 13:57:23 +1100 | [diff] [blame] | 73 | struct rcu_head rcu; |
Eric Dumazet | b9ebafb | 2015-02-20 06:48:57 -0800 | [diff] [blame] | 74 | |
Herbert Xu | c4db884 | 2015-03-14 13:57:25 +1100 | [diff] [blame] | 75 | struct bucket_table __rcu *future_tbl; |
| 76 | |
Eric Dumazet | b9ebafb | 2015-02-20 06:48:57 -0800 | [diff] [blame] | 77 | struct rhash_head __rcu *buckets[] ____cacheline_aligned_in_smp; |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 78 | }; |
| 79 | |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 80 | /** |
| 81 | * struct rhashtable_compare_arg - Key for the function rhashtable_compare |
| 82 | * @ht: Hash table |
| 83 | * @key: Key to compare against |
| 84 | */ |
| 85 | struct rhashtable_compare_arg { |
| 86 | struct rhashtable *ht; |
| 87 | const void *key; |
| 88 | }; |
| 89 | |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 90 | typedef u32 (*rht_hashfn_t)(const void *data, u32 len, u32 seed); |
| 91 | typedef u32 (*rht_obj_hashfn_t)(const void *data, u32 seed); |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 92 | typedef int (*rht_obj_cmpfn_t)(struct rhashtable_compare_arg *arg, |
| 93 | const void *obj); |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 94 | |
| 95 | struct rhashtable; |
| 96 | |
| 97 | /** |
| 98 | * struct rhashtable_params - Hash table construction parameters |
| 99 | * @nelem_hint: Hint on number of elements, should be 75% of desired size |
| 100 | * @key_len: Length of key |
| 101 | * @key_offset: Offset of key in struct to be hashed |
| 102 | * @head_offset: Offset of rhash_head in struct to be hashed |
Herbert Xu | c2e213c | 2015-03-18 20:01:16 +1100 | [diff] [blame] | 103 | * @max_size: Maximum size while expanding |
| 104 | * @min_size: Minimum size while shrinking |
Thomas Graf | f89bd6f | 2015-01-02 23:00:21 +0100 | [diff] [blame] | 105 | * @nulls_base: Base value to generate nulls marker |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 106 | * @insecure_elasticity: Set to true to disable chain length checks |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 107 | * @locks_mul: Number of bucket locks to allocate per cpu (default: 128) |
Herbert Xu | 31ccde2 | 2015-03-24 00:50:21 +1100 | [diff] [blame] | 108 | * @hashfn: Hash function (default: jhash2 if !(key_len % 4), or jhash) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 109 | * @obj_hashfn: Function to hash object |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 110 | * @obj_cmpfn: Function to compare key with object |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 111 | */ |
| 112 | struct rhashtable_params { |
| 113 | size_t nelem_hint; |
| 114 | size_t key_len; |
| 115 | size_t key_offset; |
| 116 | size_t head_offset; |
Herbert Xu | c2e213c | 2015-03-18 20:01:16 +1100 | [diff] [blame] | 117 | unsigned int max_size; |
| 118 | unsigned int min_size; |
Thomas Graf | f89bd6f | 2015-01-02 23:00:21 +0100 | [diff] [blame] | 119 | u32 nulls_base; |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 120 | bool insecure_elasticity; |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 121 | size_t locks_mul; |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 122 | rht_hashfn_t hashfn; |
| 123 | rht_obj_hashfn_t obj_hashfn; |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 124 | rht_obj_cmpfn_t obj_cmpfn; |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 125 | }; |
| 126 | |
| 127 | /** |
| 128 | * struct rhashtable - Hash table handle |
| 129 | * @tbl: Bucket table |
| 130 | * @nelems: Number of elements in table |
Herbert Xu | 31ccde2 | 2015-03-24 00:50:21 +1100 | [diff] [blame] | 131 | * @key_len: Key length for hashfn |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 132 | * @elasticity: Maximum chain length before rehash |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 133 | * @p: Configuration parameters |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 134 | * @run_work: Deferred worker to expand/shrink asynchronously |
| 135 | * @mutex: Mutex to protect current/future table swapping |
Herbert Xu | ba7c95e | 2015-03-24 09:53:17 +1100 | [diff] [blame] | 136 | * @lock: Spin lock to protect walker list |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 137 | * @being_destroyed: True if table is set up for destruction |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 138 | */ |
| 139 | struct rhashtable { |
| 140 | struct bucket_table __rcu *tbl; |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 141 | atomic_t nelems; |
Daniel Borkmann | a5b6846 | 2015-03-12 15:28:40 +0100 | [diff] [blame] | 142 | bool being_destroyed; |
Herbert Xu | 31ccde2 | 2015-03-24 00:50:21 +1100 | [diff] [blame] | 143 | unsigned int key_len; |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 144 | unsigned int elasticity; |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 145 | struct rhashtable_params p; |
Ying Xue | 57699a4 | 2015-01-16 11:13:09 +0800 | [diff] [blame] | 146 | struct work_struct run_work; |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 147 | struct mutex mutex; |
Herbert Xu | ba7c95e | 2015-03-24 09:53:17 +1100 | [diff] [blame] | 148 | spinlock_t lock; |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 149 | }; |
| 150 | |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 151 | /** |
| 152 | * struct rhashtable_walker - Hash table walker |
| 153 | * @list: List entry on list of walkers |
Herbert Xu | eddee5ba | 2015-03-14 13:57:20 +1100 | [diff] [blame] | 154 | * @tbl: The table that we were walking over |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 155 | */ |
| 156 | struct rhashtable_walker { |
| 157 | struct list_head list; |
Herbert Xu | eddee5ba | 2015-03-14 13:57:20 +1100 | [diff] [blame] | 158 | struct bucket_table *tbl; |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 159 | }; |
| 160 | |
| 161 | /** |
| 162 | * struct rhashtable_iter - Hash table iterator, fits into netlink cb |
| 163 | * @ht: Table to iterate through |
| 164 | * @p: Current pointer |
| 165 | * @walker: Associated rhashtable walker |
| 166 | * @slot: Current slot |
| 167 | * @skip: Number of entries to skip in slot |
| 168 | */ |
| 169 | struct rhashtable_iter { |
| 170 | struct rhashtable *ht; |
| 171 | struct rhash_head *p; |
| 172 | struct rhashtable_walker *walker; |
| 173 | unsigned int slot; |
| 174 | unsigned int skip; |
| 175 | }; |
| 176 | |
Thomas Graf | f89bd6f | 2015-01-02 23:00:21 +0100 | [diff] [blame] | 177 | static inline unsigned long rht_marker(const struct rhashtable *ht, u32 hash) |
| 178 | { |
| 179 | return NULLS_MARKER(ht->p.nulls_base + hash); |
| 180 | } |
| 181 | |
| 182 | #define INIT_RHT_NULLS_HEAD(ptr, ht, hash) \ |
| 183 | ((ptr) = (typeof(ptr)) rht_marker(ht, hash)) |
| 184 | |
| 185 | static inline bool rht_is_a_nulls(const struct rhash_head *ptr) |
| 186 | { |
| 187 | return ((unsigned long) ptr & 1); |
| 188 | } |
| 189 | |
| 190 | static inline unsigned long rht_get_nulls_value(const struct rhash_head *ptr) |
| 191 | { |
| 192 | return ((unsigned long) ptr) >> 1; |
| 193 | } |
| 194 | |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 195 | static inline void *rht_obj(const struct rhashtable *ht, |
| 196 | const struct rhash_head *he) |
| 197 | { |
| 198 | return (char *)he - ht->p.head_offset; |
| 199 | } |
| 200 | |
| 201 | static inline unsigned int rht_bucket_index(const struct bucket_table *tbl, |
| 202 | unsigned int hash) |
| 203 | { |
| 204 | return (hash >> RHT_HASH_RESERVED_SPACE) & (tbl->size - 1); |
| 205 | } |
| 206 | |
| 207 | static inline unsigned int rht_key_hashfn( |
| 208 | struct rhashtable *ht, const struct bucket_table *tbl, |
| 209 | const void *key, const struct rhashtable_params params) |
| 210 | { |
Herbert Xu | 31ccde2 | 2015-03-24 00:50:21 +1100 | [diff] [blame] | 211 | unsigned hash; |
Herbert Xu | de91b25 | 2015-03-24 00:50:20 +1100 | [diff] [blame] | 212 | |
Herbert Xu | 31ccde2 | 2015-03-24 00:50:21 +1100 | [diff] [blame] | 213 | /* params must be equal to ht->p if it isn't constant. */ |
| 214 | if (!__builtin_constant_p(params.key_len)) |
| 215 | hash = ht->p.hashfn(key, ht->key_len, tbl->hash_rnd); |
| 216 | else if (params.key_len) { |
| 217 | unsigned key_len = params.key_len; |
| 218 | |
| 219 | if (params.hashfn) |
| 220 | hash = params.hashfn(key, key_len, tbl->hash_rnd); |
| 221 | else if (key_len & (sizeof(u32) - 1)) |
| 222 | hash = jhash(key, key_len, tbl->hash_rnd); |
| 223 | else |
| 224 | hash = jhash2(key, key_len / sizeof(u32), |
| 225 | tbl->hash_rnd); |
| 226 | } else { |
| 227 | unsigned key_len = ht->p.key_len; |
| 228 | |
| 229 | if (params.hashfn) |
| 230 | hash = params.hashfn(key, key_len, tbl->hash_rnd); |
| 231 | else |
| 232 | hash = jhash(key, key_len, tbl->hash_rnd); |
| 233 | } |
| 234 | |
| 235 | return rht_bucket_index(tbl, hash); |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 236 | } |
| 237 | |
| 238 | static inline unsigned int rht_head_hashfn( |
| 239 | struct rhashtable *ht, const struct bucket_table *tbl, |
| 240 | const struct rhash_head *he, const struct rhashtable_params params) |
| 241 | { |
| 242 | const char *ptr = rht_obj(ht, he); |
| 243 | |
| 244 | return likely(params.obj_hashfn) ? |
| 245 | rht_bucket_index(tbl, params.obj_hashfn(ptr, tbl->hash_rnd)) : |
| 246 | rht_key_hashfn(ht, tbl, ptr + params.key_offset, params); |
| 247 | } |
| 248 | |
| 249 | /** |
| 250 | * rht_grow_above_75 - returns true if nelems > 0.75 * table-size |
| 251 | * @ht: hash table |
| 252 | * @tbl: current table |
| 253 | */ |
| 254 | static inline bool rht_grow_above_75(const struct rhashtable *ht, |
| 255 | const struct bucket_table *tbl) |
| 256 | { |
| 257 | /* Expand table when exceeding 75% load */ |
| 258 | return atomic_read(&ht->nelems) > (tbl->size / 4 * 3) && |
| 259 | (!ht->p.max_size || tbl->size < ht->p.max_size); |
| 260 | } |
| 261 | |
| 262 | /** |
| 263 | * rht_shrink_below_30 - returns true if nelems < 0.3 * table-size |
| 264 | * @ht: hash table |
| 265 | * @tbl: current table |
| 266 | */ |
| 267 | static inline bool rht_shrink_below_30(const struct rhashtable *ht, |
| 268 | const struct bucket_table *tbl) |
| 269 | { |
| 270 | /* Shrink table beneath 30% load */ |
| 271 | return atomic_read(&ht->nelems) < (tbl->size * 3 / 10) && |
| 272 | tbl->size > ht->p.min_size; |
| 273 | } |
| 274 | |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 275 | /** |
| 276 | * rht_grow_above_100 - returns true if nelems > table-size |
| 277 | * @ht: hash table |
| 278 | * @tbl: current table |
| 279 | */ |
| 280 | static inline bool rht_grow_above_100(const struct rhashtable *ht, |
| 281 | const struct bucket_table *tbl) |
| 282 | { |
| 283 | return atomic_read(&ht->nelems) > tbl->size; |
| 284 | } |
| 285 | |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 286 | /* The bucket lock is selected based on the hash and protects mutations |
| 287 | * on a group of hash buckets. |
| 288 | * |
| 289 | * A maximum of tbl->size/2 bucket locks is allocated. This ensures that |
| 290 | * a single lock always covers both buckets which may both contains |
| 291 | * entries which link to the same bucket of the old table during resizing. |
| 292 | * This allows to simplify the locking as locking the bucket in both |
| 293 | * tables during resize always guarantee protection. |
| 294 | * |
| 295 | * IMPORTANT: When holding the bucket lock of both the old and new table |
| 296 | * during expansions and shrinking, the old bucket lock must always be |
| 297 | * acquired first. |
| 298 | */ |
| 299 | static inline spinlock_t *rht_bucket_lock(const struct bucket_table *tbl, |
| 300 | unsigned int hash) |
| 301 | { |
| 302 | return &tbl->locks[hash & tbl->locks_mask]; |
| 303 | } |
| 304 | |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 305 | #ifdef CONFIG_PROVE_LOCKING |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 306 | int lockdep_rht_mutex_is_held(struct rhashtable *ht); |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 307 | int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash); |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 308 | #else |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 309 | static inline int lockdep_rht_mutex_is_held(struct rhashtable *ht) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 310 | { |
| 311 | return 1; |
| 312 | } |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 313 | |
| 314 | static inline int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, |
| 315 | u32 hash) |
| 316 | { |
| 317 | return 1; |
| 318 | } |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 319 | #endif /* CONFIG_PROVE_LOCKING */ |
| 320 | |
Herbert Xu | 488fb86e | 2015-03-20 21:56:59 +1100 | [diff] [blame] | 321 | int rhashtable_init(struct rhashtable *ht, |
| 322 | const struct rhashtable_params *params); |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 323 | |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 324 | int rhashtable_insert_slow(struct rhashtable *ht, const void *key, |
| 325 | struct rhash_head *obj, |
| 326 | struct bucket_table *old_tbl); |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 327 | int rhashtable_insert_rehash(struct rhashtable *ht); |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 328 | |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 329 | int rhashtable_walk_init(struct rhashtable *ht, struct rhashtable_iter *iter); |
| 330 | void rhashtable_walk_exit(struct rhashtable_iter *iter); |
| 331 | int rhashtable_walk_start(struct rhashtable_iter *iter) __acquires(RCU); |
| 332 | void *rhashtable_walk_next(struct rhashtable_iter *iter); |
| 333 | void rhashtable_walk_stop(struct rhashtable_iter *iter) __releases(RCU); |
| 334 | |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 335 | void rhashtable_destroy(struct rhashtable *ht); |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 336 | |
| 337 | #define rht_dereference(p, ht) \ |
| 338 | rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht)) |
| 339 | |
| 340 | #define rht_dereference_rcu(p, ht) \ |
| 341 | rcu_dereference_check(p, lockdep_rht_mutex_is_held(ht)) |
| 342 | |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 343 | #define rht_dereference_bucket(p, tbl, hash) \ |
| 344 | rcu_dereference_protected(p, lockdep_rht_bucket_is_held(tbl, hash)) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 345 | |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 346 | #define rht_dereference_bucket_rcu(p, tbl, hash) \ |
| 347 | rcu_dereference_check(p, lockdep_rht_bucket_is_held(tbl, hash)) |
| 348 | |
| 349 | #define rht_entry(tpos, pos, member) \ |
| 350 | ({ tpos = container_of(pos, typeof(*tpos), member); 1; }) |
| 351 | |
| 352 | /** |
| 353 | * rht_for_each_continue - continue iterating over hash chain |
| 354 | * @pos: the &struct rhash_head to use as a loop cursor. |
| 355 | * @head: the previous &struct rhash_head to continue from |
| 356 | * @tbl: the &struct bucket_table |
| 357 | * @hash: the hash value / bucket index |
| 358 | */ |
| 359 | #define rht_for_each_continue(pos, head, tbl, hash) \ |
| 360 | for (pos = rht_dereference_bucket(head, tbl, hash); \ |
Thomas Graf | f89bd6f | 2015-01-02 23:00:21 +0100 | [diff] [blame] | 361 | !rht_is_a_nulls(pos); \ |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 362 | pos = rht_dereference_bucket((pos)->next, tbl, hash)) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 363 | |
| 364 | /** |
| 365 | * rht_for_each - iterate over hash chain |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 366 | * @pos: the &struct rhash_head to use as a loop cursor. |
| 367 | * @tbl: the &struct bucket_table |
| 368 | * @hash: the hash value / bucket index |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 369 | */ |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 370 | #define rht_for_each(pos, tbl, hash) \ |
| 371 | rht_for_each_continue(pos, (tbl)->buckets[hash], tbl, hash) |
| 372 | |
| 373 | /** |
| 374 | * rht_for_each_entry_continue - continue iterating over hash chain |
| 375 | * @tpos: the type * to use as a loop cursor. |
| 376 | * @pos: the &struct rhash_head to use as a loop cursor. |
| 377 | * @head: the previous &struct rhash_head to continue from |
| 378 | * @tbl: the &struct bucket_table |
| 379 | * @hash: the hash value / bucket index |
| 380 | * @member: name of the &struct rhash_head within the hashable struct. |
| 381 | */ |
| 382 | #define rht_for_each_entry_continue(tpos, pos, head, tbl, hash, member) \ |
| 383 | for (pos = rht_dereference_bucket(head, tbl, hash); \ |
Thomas Graf | f89bd6f | 2015-01-02 23:00:21 +0100 | [diff] [blame] | 384 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \ |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 385 | pos = rht_dereference_bucket((pos)->next, tbl, hash)) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 386 | |
| 387 | /** |
| 388 | * rht_for_each_entry - iterate over hash chain of given type |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 389 | * @tpos: the type * to use as a loop cursor. |
| 390 | * @pos: the &struct rhash_head to use as a loop cursor. |
| 391 | * @tbl: the &struct bucket_table |
| 392 | * @hash: the hash value / bucket index |
| 393 | * @member: name of the &struct rhash_head within the hashable struct. |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 394 | */ |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 395 | #define rht_for_each_entry(tpos, pos, tbl, hash, member) \ |
| 396 | rht_for_each_entry_continue(tpos, pos, (tbl)->buckets[hash], \ |
| 397 | tbl, hash, member) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 398 | |
| 399 | /** |
| 400 | * rht_for_each_entry_safe - safely iterate over hash chain of given type |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 401 | * @tpos: the type * to use as a loop cursor. |
| 402 | * @pos: the &struct rhash_head to use as a loop cursor. |
| 403 | * @next: the &struct rhash_head to use as next in loop cursor. |
| 404 | * @tbl: the &struct bucket_table |
| 405 | * @hash: the hash value / bucket index |
| 406 | * @member: name of the &struct rhash_head within the hashable struct. |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 407 | * |
| 408 | * This hash chain list-traversal primitive allows for the looped code to |
| 409 | * remove the loop cursor from the list. |
| 410 | */ |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 411 | #define rht_for_each_entry_safe(tpos, pos, next, tbl, hash, member) \ |
| 412 | for (pos = rht_dereference_bucket((tbl)->buckets[hash], tbl, hash), \ |
Thomas Graf | f89bd6f | 2015-01-02 23:00:21 +0100 | [diff] [blame] | 413 | next = !rht_is_a_nulls(pos) ? \ |
| 414 | rht_dereference_bucket(pos->next, tbl, hash) : NULL; \ |
| 415 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \ |
Patrick McHardy | 607954b | 2015-01-21 11:12:13 +0000 | [diff] [blame] | 416 | pos = next, \ |
| 417 | next = !rht_is_a_nulls(pos) ? \ |
| 418 | rht_dereference_bucket(pos->next, tbl, hash) : NULL) |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 419 | |
| 420 | /** |
| 421 | * rht_for_each_rcu_continue - continue iterating over rcu hash chain |
| 422 | * @pos: the &struct rhash_head to use as a loop cursor. |
| 423 | * @head: the previous &struct rhash_head to continue from |
| 424 | * @tbl: the &struct bucket_table |
| 425 | * @hash: the hash value / bucket index |
| 426 | * |
| 427 | * This hash chain list-traversal primitive may safely run concurrently with |
| 428 | * the _rcu mutation primitives such as rhashtable_insert() as long as the |
| 429 | * traversal is guarded by rcu_read_lock(). |
| 430 | */ |
| 431 | #define rht_for_each_rcu_continue(pos, head, tbl, hash) \ |
| 432 | for (({barrier(); }), \ |
| 433 | pos = rht_dereference_bucket_rcu(head, tbl, hash); \ |
Thomas Graf | f89bd6f | 2015-01-02 23:00:21 +0100 | [diff] [blame] | 434 | !rht_is_a_nulls(pos); \ |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 435 | pos = rcu_dereference_raw(pos->next)) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 436 | |
| 437 | /** |
| 438 | * rht_for_each_rcu - iterate over rcu hash chain |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 439 | * @pos: the &struct rhash_head to use as a loop cursor. |
| 440 | * @tbl: the &struct bucket_table |
| 441 | * @hash: the hash value / bucket index |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 442 | * |
| 443 | * This hash chain list-traversal primitive may safely run concurrently with |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 444 | * the _rcu mutation primitives such as rhashtable_insert() as long as the |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 445 | * traversal is guarded by rcu_read_lock(). |
| 446 | */ |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 447 | #define rht_for_each_rcu(pos, tbl, hash) \ |
| 448 | rht_for_each_rcu_continue(pos, (tbl)->buckets[hash], tbl, hash) |
| 449 | |
| 450 | /** |
| 451 | * rht_for_each_entry_rcu_continue - continue iterating over rcu hash chain |
| 452 | * @tpos: the type * to use as a loop cursor. |
| 453 | * @pos: the &struct rhash_head to use as a loop cursor. |
| 454 | * @head: the previous &struct rhash_head to continue from |
| 455 | * @tbl: the &struct bucket_table |
| 456 | * @hash: the hash value / bucket index |
| 457 | * @member: name of the &struct rhash_head within the hashable struct. |
| 458 | * |
| 459 | * This hash chain list-traversal primitive may safely run concurrently with |
| 460 | * the _rcu mutation primitives such as rhashtable_insert() as long as the |
| 461 | * traversal is guarded by rcu_read_lock(). |
| 462 | */ |
| 463 | #define rht_for_each_entry_rcu_continue(tpos, pos, head, tbl, hash, member) \ |
| 464 | for (({barrier(); }), \ |
| 465 | pos = rht_dereference_bucket_rcu(head, tbl, hash); \ |
Thomas Graf | f89bd6f | 2015-01-02 23:00:21 +0100 | [diff] [blame] | 466 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \ |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 467 | pos = rht_dereference_bucket_rcu(pos->next, tbl, hash)) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 468 | |
| 469 | /** |
| 470 | * rht_for_each_entry_rcu - iterate over rcu hash chain of given type |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 471 | * @tpos: the type * to use as a loop cursor. |
| 472 | * @pos: the &struct rhash_head to use as a loop cursor. |
| 473 | * @tbl: the &struct bucket_table |
| 474 | * @hash: the hash value / bucket index |
| 475 | * @member: name of the &struct rhash_head within the hashable struct. |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 476 | * |
| 477 | * This hash chain list-traversal primitive may safely run concurrently with |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 478 | * the _rcu mutation primitives such as rhashtable_insert() as long as the |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 479 | * traversal is guarded by rcu_read_lock(). |
| 480 | */ |
Thomas Graf | 88d6ed1 | 2015-01-02 23:00:16 +0100 | [diff] [blame] | 481 | #define rht_for_each_entry_rcu(tpos, pos, tbl, hash, member) \ |
| 482 | rht_for_each_entry_rcu_continue(tpos, pos, (tbl)->buckets[hash],\ |
| 483 | tbl, hash, member) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 484 | |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 485 | static inline int rhashtable_compare(struct rhashtable_compare_arg *arg, |
| 486 | const void *obj) |
| 487 | { |
| 488 | struct rhashtable *ht = arg->ht; |
| 489 | const char *ptr = obj; |
| 490 | |
| 491 | return memcmp(ptr + ht->p.key_offset, arg->key, ht->p.key_len); |
| 492 | } |
| 493 | |
| 494 | /** |
| 495 | * rhashtable_lookup_fast - search hash table, inlined version |
| 496 | * @ht: hash table |
| 497 | * @key: the pointer to the key |
| 498 | * @params: hash table parameters |
| 499 | * |
| 500 | * Computes the hash value for the key and traverses the bucket chain looking |
| 501 | * for a entry with an identical key. The first matching entry is returned. |
| 502 | * |
| 503 | * Returns the first entry on which the compare function returned true. |
| 504 | */ |
| 505 | static inline void *rhashtable_lookup_fast( |
| 506 | struct rhashtable *ht, const void *key, |
| 507 | const struct rhashtable_params params) |
| 508 | { |
| 509 | struct rhashtable_compare_arg arg = { |
| 510 | .ht = ht, |
| 511 | .key = key, |
| 512 | }; |
| 513 | const struct bucket_table *tbl; |
| 514 | struct rhash_head *he; |
| 515 | unsigned hash; |
| 516 | |
| 517 | rcu_read_lock(); |
| 518 | |
| 519 | tbl = rht_dereference_rcu(ht->tbl, ht); |
| 520 | restart: |
| 521 | hash = rht_key_hashfn(ht, tbl, key, params); |
| 522 | rht_for_each_rcu(he, tbl, hash) { |
| 523 | if (params.obj_cmpfn ? |
| 524 | params.obj_cmpfn(&arg, rht_obj(ht, he)) : |
| 525 | rhashtable_compare(&arg, rht_obj(ht, he))) |
| 526 | continue; |
| 527 | rcu_read_unlock(); |
| 528 | return rht_obj(ht, he); |
| 529 | } |
| 530 | |
| 531 | /* Ensure we see any new tables. */ |
| 532 | smp_rmb(); |
| 533 | |
| 534 | tbl = rht_dereference_rcu(tbl->future_tbl, ht); |
| 535 | if (unlikely(tbl)) |
| 536 | goto restart; |
| 537 | rcu_read_unlock(); |
| 538 | |
| 539 | return NULL; |
| 540 | } |
| 541 | |
| 542 | static inline int __rhashtable_insert_fast( |
| 543 | struct rhashtable *ht, const void *key, struct rhash_head *obj, |
| 544 | const struct rhashtable_params params) |
| 545 | { |
| 546 | struct rhashtable_compare_arg arg = { |
| 547 | .ht = ht, |
| 548 | .key = key, |
| 549 | }; |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 550 | struct bucket_table *tbl, *new_tbl; |
| 551 | struct rhash_head *head; |
| 552 | spinlock_t *lock; |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 553 | unsigned elasticity; |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 554 | unsigned hash; |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 555 | int err; |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 556 | |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 557 | restart: |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 558 | rcu_read_lock(); |
| 559 | |
| 560 | tbl = rht_dereference_rcu(ht->tbl, ht); |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 561 | |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 562 | /* All insertions must grab the oldest table containing |
| 563 | * the hashed bucket that is yet to be rehashed. |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 564 | */ |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 565 | for (;;) { |
| 566 | hash = rht_head_hashfn(ht, tbl, obj, params); |
| 567 | lock = rht_bucket_lock(tbl, hash); |
| 568 | spin_lock_bh(lock); |
| 569 | |
| 570 | if (tbl->rehash <= hash) |
| 571 | break; |
| 572 | |
| 573 | spin_unlock_bh(lock); |
| 574 | tbl = rht_dereference_rcu(tbl->future_tbl, ht); |
| 575 | } |
| 576 | |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 577 | new_tbl = rht_dereference_rcu(tbl->future_tbl, ht); |
| 578 | if (unlikely(new_tbl)) { |
| 579 | err = rhashtable_insert_slow(ht, key, obj, new_tbl); |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 580 | if (err == -EAGAIN) |
| 581 | goto slow_path; |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 582 | goto out; |
| 583 | } |
| 584 | |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 585 | if (unlikely(rht_grow_above_100(ht, tbl))) { |
| 586 | slow_path: |
| 587 | spin_unlock_bh(lock); |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 588 | err = rhashtable_insert_rehash(ht); |
Thomas Graf | 58be8a5 | 2015-03-24 14:18:16 +0100 | [diff] [blame^] | 589 | rcu_read_unlock(); |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 590 | if (err) |
| 591 | return err; |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 592 | |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 593 | goto restart; |
| 594 | } |
| 595 | |
| 596 | err = -EEXIST; |
| 597 | elasticity = ht->elasticity; |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 598 | rht_for_each(head, tbl, hash) { |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 599 | if (key && |
| 600 | unlikely(!(params.obj_cmpfn ? |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 601 | params.obj_cmpfn(&arg, rht_obj(ht, head)) : |
| 602 | rhashtable_compare(&arg, rht_obj(ht, head))))) |
| 603 | goto out; |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 604 | if (!--elasticity) |
| 605 | goto slow_path; |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 606 | } |
| 607 | |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 608 | err = 0; |
| 609 | |
| 610 | head = rht_dereference_bucket(tbl->buckets[hash], tbl, hash); |
| 611 | |
| 612 | RCU_INIT_POINTER(obj->next, head); |
| 613 | |
| 614 | rcu_assign_pointer(tbl->buckets[hash], obj); |
| 615 | |
| 616 | atomic_inc(&ht->nelems); |
| 617 | if (rht_grow_above_75(ht, tbl)) |
| 618 | schedule_work(&ht->run_work); |
| 619 | |
| 620 | out: |
| 621 | spin_unlock_bh(lock); |
| 622 | rcu_read_unlock(); |
| 623 | |
| 624 | return err; |
| 625 | } |
| 626 | |
| 627 | /** |
| 628 | * rhashtable_insert_fast - insert object into hash table |
| 629 | * @ht: hash table |
| 630 | * @obj: pointer to hash head inside object |
| 631 | * @params: hash table parameters |
| 632 | * |
| 633 | * Will take a per bucket spinlock to protect against mutual mutations |
| 634 | * on the same bucket. Multiple insertions may occur in parallel unless |
| 635 | * they map to the same bucket lock. |
| 636 | * |
| 637 | * It is safe to call this function from atomic context. |
| 638 | * |
| 639 | * Will trigger an automatic deferred table resizing if the size grows |
| 640 | * beyond the watermark indicated by grow_decision() which can be passed |
| 641 | * to rhashtable_init(). |
| 642 | */ |
| 643 | static inline int rhashtable_insert_fast( |
| 644 | struct rhashtable *ht, struct rhash_head *obj, |
| 645 | const struct rhashtable_params params) |
| 646 | { |
| 647 | return __rhashtable_insert_fast(ht, NULL, obj, params); |
| 648 | } |
| 649 | |
| 650 | /** |
| 651 | * rhashtable_lookup_insert_fast - lookup and insert object into hash table |
| 652 | * @ht: hash table |
| 653 | * @obj: pointer to hash head inside object |
| 654 | * @params: hash table parameters |
| 655 | * |
| 656 | * Locks down the bucket chain in both the old and new table if a resize |
| 657 | * is in progress to ensure that writers can't remove from the old table |
| 658 | * and can't insert to the new table during the atomic operation of search |
| 659 | * and insertion. Searches for duplicates in both the old and new table if |
| 660 | * a resize is in progress. |
| 661 | * |
| 662 | * This lookup function may only be used for fixed key hash table (key_len |
| 663 | * parameter set). It will BUG() if used inappropriately. |
| 664 | * |
| 665 | * It is safe to call this function from atomic context. |
| 666 | * |
| 667 | * Will trigger an automatic deferred table resizing if the size grows |
| 668 | * beyond the watermark indicated by grow_decision() which can be passed |
| 669 | * to rhashtable_init(). |
| 670 | */ |
| 671 | static inline int rhashtable_lookup_insert_fast( |
| 672 | struct rhashtable *ht, struct rhash_head *obj, |
| 673 | const struct rhashtable_params params) |
| 674 | { |
| 675 | const char *key = rht_obj(ht, obj); |
| 676 | |
| 677 | BUG_ON(ht->p.obj_hashfn); |
| 678 | |
| 679 | return __rhashtable_insert_fast(ht, key + ht->p.key_offset, obj, |
| 680 | params); |
| 681 | } |
| 682 | |
| 683 | /** |
| 684 | * rhashtable_lookup_insert_key - search and insert object to hash table |
| 685 | * with explicit key |
| 686 | * @ht: hash table |
| 687 | * @key: key |
| 688 | * @obj: pointer to hash head inside object |
| 689 | * @params: hash table parameters |
| 690 | * |
| 691 | * Locks down the bucket chain in both the old and new table if a resize |
| 692 | * is in progress to ensure that writers can't remove from the old table |
| 693 | * and can't insert to the new table during the atomic operation of search |
| 694 | * and insertion. Searches for duplicates in both the old and new table if |
| 695 | * a resize is in progress. |
| 696 | * |
| 697 | * Lookups may occur in parallel with hashtable mutations and resizing. |
| 698 | * |
| 699 | * Will trigger an automatic deferred table resizing if the size grows |
| 700 | * beyond the watermark indicated by grow_decision() which can be passed |
| 701 | * to rhashtable_init(). |
| 702 | * |
| 703 | * Returns zero on success. |
| 704 | */ |
| 705 | static inline int rhashtable_lookup_insert_key( |
| 706 | struct rhashtable *ht, const void *key, struct rhash_head *obj, |
| 707 | const struct rhashtable_params params) |
| 708 | { |
| 709 | BUG_ON(!ht->p.obj_hashfn || !key); |
| 710 | |
| 711 | return __rhashtable_insert_fast(ht, key, obj, params); |
| 712 | } |
| 713 | |
| 714 | static inline int __rhashtable_remove_fast( |
| 715 | struct rhashtable *ht, struct bucket_table *tbl, |
| 716 | struct rhash_head *obj, const struct rhashtable_params params) |
| 717 | { |
| 718 | struct rhash_head __rcu **pprev; |
| 719 | struct rhash_head *he; |
| 720 | spinlock_t * lock; |
| 721 | unsigned hash; |
| 722 | int err = -ENOENT; |
| 723 | |
| 724 | hash = rht_head_hashfn(ht, tbl, obj, params); |
| 725 | lock = rht_bucket_lock(tbl, hash); |
| 726 | |
| 727 | spin_lock_bh(lock); |
| 728 | |
| 729 | pprev = &tbl->buckets[hash]; |
| 730 | rht_for_each(he, tbl, hash) { |
| 731 | if (he != obj) { |
| 732 | pprev = &he->next; |
| 733 | continue; |
| 734 | } |
| 735 | |
| 736 | rcu_assign_pointer(*pprev, obj->next); |
| 737 | err = 0; |
| 738 | break; |
| 739 | } |
| 740 | |
| 741 | spin_unlock_bh(lock); |
| 742 | |
| 743 | return err; |
| 744 | } |
| 745 | |
| 746 | /** |
| 747 | * rhashtable_remove_fast - remove object from hash table |
| 748 | * @ht: hash table |
| 749 | * @obj: pointer to hash head inside object |
| 750 | * @params: hash table parameters |
| 751 | * |
| 752 | * Since the hash chain is single linked, the removal operation needs to |
| 753 | * walk the bucket chain upon removal. The removal operation is thus |
| 754 | * considerable slow if the hash table is not correctly sized. |
| 755 | * |
| 756 | * Will automatically shrink the table via rhashtable_expand() if the |
| 757 | * shrink_decision function specified at rhashtable_init() returns true. |
| 758 | * |
| 759 | * Returns zero on success, -ENOENT if the entry could not be found. |
| 760 | */ |
| 761 | static inline int rhashtable_remove_fast( |
| 762 | struct rhashtable *ht, struct rhash_head *obj, |
| 763 | const struct rhashtable_params params) |
| 764 | { |
| 765 | struct bucket_table *tbl; |
| 766 | int err; |
| 767 | |
| 768 | rcu_read_lock(); |
| 769 | |
| 770 | tbl = rht_dereference_rcu(ht->tbl, ht); |
| 771 | |
| 772 | /* Because we have already taken (and released) the bucket |
| 773 | * lock in old_tbl, if we find that future_tbl is not yet |
| 774 | * visible then that guarantees the entry to still be in |
| 775 | * the old tbl if it exists. |
| 776 | */ |
| 777 | while ((err = __rhashtable_remove_fast(ht, tbl, obj, params)) && |
| 778 | (tbl = rht_dereference_rcu(tbl->future_tbl, ht))) |
| 779 | ; |
| 780 | |
| 781 | if (err) |
| 782 | goto out; |
| 783 | |
| 784 | atomic_dec(&ht->nelems); |
| 785 | if (rht_shrink_below_30(ht, tbl)) |
| 786 | schedule_work(&ht->run_work); |
| 787 | |
| 788 | out: |
| 789 | rcu_read_unlock(); |
| 790 | |
| 791 | return err; |
| 792 | } |
| 793 | |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 794 | #endif /* _LINUX_RHASHTABLE_H */ |