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7e1e7763 TG |
1 | /* |
2 | * Resizable, Scalable, Concurrent Hash Table | |
3 | * | |
dc0ee268 | 4 | * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au> |
b5e2c150 | 5 | * Copyright (c) 2014-2015 Thomas Graf <tgraf@suug.ch> |
7e1e7763 TG |
6 | * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net> |
7 | * | |
7e1e7763 | 8 | * Code partially derived from nft_hash |
dc0ee268 HX |
9 | * Rewritten with rehash code from br_multicast plus single list |
10 | * pointer as suggested by Josh Triplett | |
7e1e7763 TG |
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 | ||
f2dba9c6 | 20 | #include <linux/compiler.h> |
6626af69 | 21 | #include <linux/errno.h> |
31ccde2d | 22 | #include <linux/jhash.h> |
f89bd6f8 | 23 | #include <linux/list_nulls.h> |
97defe1e | 24 | #include <linux/workqueue.h> |
86b35b64 | 25 | #include <linux/mutex.h> |
02fd97c3 | 26 | #include <linux/rcupdate.h> |
7e1e7763 | 27 | |
f89bd6f8 TG |
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 | ||
02fd97c3 HX |
47 | /* Base bits plus 1 bit for nulls marker */ |
48 | #define RHT_HASH_RESERVED_SPACE (RHT_BASE_BITS + 1) | |
49 | ||
7e1e7763 | 50 | struct rhash_head { |
5300fdcb | 51 | struct rhash_head __rcu *next; |
7e1e7763 TG |
52 | }; |
53 | ||
97defe1e TG |
54 | /** |
55 | * struct bucket_table - Table of hash buckets | |
56 | * @size: Number of hash buckets | |
63d512d0 | 57 | * @rehash: Current bucket being rehashed |
988dfbd7 | 58 | * @hash_rnd: Random seed to fold into hash |
97defe1e TG |
59 | * @locks_mask: Mask to apply before accessing locks[] |
60 | * @locks: Array of spinlocks protecting individual buckets | |
eddee5ba | 61 | * @walkers: List of active walkers |
9d901bc0 | 62 | * @rcu: RCU structure for freeing the table |
c4db8848 | 63 | * @future_tbl: Table under construction during rehashing |
97defe1e TG |
64 | * @buckets: size * hash buckets |
65 | */ | |
7e1e7763 | 66 | struct bucket_table { |
63d512d0 HX |
67 | unsigned int size; |
68 | unsigned int rehash; | |
988dfbd7 | 69 | u32 hash_rnd; |
b9ebafbe ED |
70 | unsigned int locks_mask; |
71 | spinlock_t *locks; | |
eddee5ba | 72 | struct list_head walkers; |
9d901bc0 | 73 | struct rcu_head rcu; |
b9ebafbe | 74 | |
c4db8848 HX |
75 | struct bucket_table __rcu *future_tbl; |
76 | ||
b9ebafbe | 77 | struct rhash_head __rcu *buckets[] ____cacheline_aligned_in_smp; |
7e1e7763 TG |
78 | }; |
79 | ||
02fd97c3 HX |
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 | ||
7e1e7763 | 90 | typedef u32 (*rht_hashfn_t)(const void *data, u32 len, u32 seed); |
49f7b33e | 91 | typedef u32 (*rht_obj_hashfn_t)(const void *data, u32 len, u32 seed); |
02fd97c3 HX |
92 | typedef int (*rht_obj_cmpfn_t)(struct rhashtable_compare_arg *arg, |
93 | const void *obj); | |
7e1e7763 TG |
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 | |
c2e213cf HX |
103 | * @max_size: Maximum size while expanding |
104 | * @min_size: Minimum size while shrinking | |
f89bd6f8 | 105 | * @nulls_base: Base value to generate nulls marker |
ccd57b1b | 106 | * @insecure_elasticity: Set to true to disable chain length checks |
b5e2c150 | 107 | * @automatic_shrinking: Enable automatic shrinking of tables |
97defe1e | 108 | * @locks_mul: Number of bucket locks to allocate per cpu (default: 128) |
31ccde2d | 109 | * @hashfn: Hash function (default: jhash2 if !(key_len % 4), or jhash) |
7e1e7763 | 110 | * @obj_hashfn: Function to hash object |
02fd97c3 | 111 | * @obj_cmpfn: Function to compare key with object |
7e1e7763 TG |
112 | */ |
113 | struct rhashtable_params { | |
114 | size_t nelem_hint; | |
115 | size_t key_len; | |
116 | size_t key_offset; | |
117 | size_t head_offset; | |
c2e213cf HX |
118 | unsigned int max_size; |
119 | unsigned int min_size; | |
f89bd6f8 | 120 | u32 nulls_base; |
ccd57b1b | 121 | bool insecure_elasticity; |
b5e2c150 | 122 | bool automatic_shrinking; |
97defe1e | 123 | size_t locks_mul; |
7e1e7763 TG |
124 | rht_hashfn_t hashfn; |
125 | rht_obj_hashfn_t obj_hashfn; | |
02fd97c3 | 126 | rht_obj_cmpfn_t obj_cmpfn; |
7e1e7763 TG |
127 | }; |
128 | ||
129 | /** | |
130 | * struct rhashtable - Hash table handle | |
131 | * @tbl: Bucket table | |
132 | * @nelems: Number of elements in table | |
31ccde2d | 133 | * @key_len: Key length for hashfn |
ccd57b1b | 134 | * @elasticity: Maximum chain length before rehash |
7e1e7763 | 135 | * @p: Configuration parameters |
97defe1e TG |
136 | * @run_work: Deferred worker to expand/shrink asynchronously |
137 | * @mutex: Mutex to protect current/future table swapping | |
ba7c95ea | 138 | * @lock: Spin lock to protect walker list |
7e1e7763 TG |
139 | */ |
140 | struct rhashtable { | |
141 | struct bucket_table __rcu *tbl; | |
97defe1e | 142 | atomic_t nelems; |
31ccde2d | 143 | unsigned int key_len; |
ccd57b1b | 144 | unsigned int elasticity; |
7e1e7763 | 145 | struct rhashtable_params p; |
57699a40 | 146 | struct work_struct run_work; |
97defe1e | 147 | struct mutex mutex; |
ba7c95ea | 148 | spinlock_t lock; |
7e1e7763 TG |
149 | }; |
150 | ||
f2dba9c6 HX |
151 | /** |
152 | * struct rhashtable_walker - Hash table walker | |
153 | * @list: List entry on list of walkers | |
eddee5ba | 154 | * @tbl: The table that we were walking over |
f2dba9c6 HX |
155 | */ |
156 | struct rhashtable_walker { | |
157 | struct list_head list; | |
eddee5ba | 158 | struct bucket_table *tbl; |
f2dba9c6 HX |
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 | ||
f89bd6f8 TG |
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 | ||
02fd97c3 HX |
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 | { | |
299e5c32 | 211 | unsigned int hash; |
de91b25c | 212 | |
31ccde2d HX |
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) { | |
299e5c32 | 217 | unsigned int key_len = params.key_len; |
31ccde2d HX |
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 { | |
299e5c32 | 227 | unsigned int key_len = ht->p.key_len; |
31ccde2d HX |
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); | |
02fd97c3 HX |
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) ? | |
49f7b33e PM |
245 | rht_bucket_index(tbl, params.obj_hashfn(ptr, params.key_len ?: |
246 | ht->p.key_len, | |
247 | tbl->hash_rnd)) : | |
02fd97c3 HX |
248 | rht_key_hashfn(ht, tbl, ptr + params.key_offset, params); |
249 | } | |
250 | ||
251 | /** | |
252 | * rht_grow_above_75 - returns true if nelems > 0.75 * table-size | |
253 | * @ht: hash table | |
254 | * @tbl: current table | |
255 | */ | |
256 | static inline bool rht_grow_above_75(const struct rhashtable *ht, | |
257 | const struct bucket_table *tbl) | |
258 | { | |
259 | /* Expand table when exceeding 75% load */ | |
260 | return atomic_read(&ht->nelems) > (tbl->size / 4 * 3) && | |
261 | (!ht->p.max_size || tbl->size < ht->p.max_size); | |
262 | } | |
263 | ||
264 | /** | |
265 | * rht_shrink_below_30 - returns true if nelems < 0.3 * table-size | |
266 | * @ht: hash table | |
267 | * @tbl: current table | |
268 | */ | |
269 | static inline bool rht_shrink_below_30(const struct rhashtable *ht, | |
270 | const struct bucket_table *tbl) | |
271 | { | |
272 | /* Shrink table beneath 30% load */ | |
273 | return atomic_read(&ht->nelems) < (tbl->size * 3 / 10) && | |
274 | tbl->size > ht->p.min_size; | |
275 | } | |
276 | ||
ccd57b1b HX |
277 | /** |
278 | * rht_grow_above_100 - returns true if nelems > table-size | |
279 | * @ht: hash table | |
280 | * @tbl: current table | |
281 | */ | |
282 | static inline bool rht_grow_above_100(const struct rhashtable *ht, | |
283 | const struct bucket_table *tbl) | |
284 | { | |
1d8dc3d3 JB |
285 | return atomic_read(&ht->nelems) > tbl->size && |
286 | (!ht->p.max_size || tbl->size < ht->p.max_size); | |
ccd57b1b HX |
287 | } |
288 | ||
02fd97c3 HX |
289 | /* The bucket lock is selected based on the hash and protects mutations |
290 | * on a group of hash buckets. | |
291 | * | |
292 | * A maximum of tbl->size/2 bucket locks is allocated. This ensures that | |
293 | * a single lock always covers both buckets which may both contains | |
294 | * entries which link to the same bucket of the old table during resizing. | |
295 | * This allows to simplify the locking as locking the bucket in both | |
296 | * tables during resize always guarantee protection. | |
297 | * | |
298 | * IMPORTANT: When holding the bucket lock of both the old and new table | |
299 | * during expansions and shrinking, the old bucket lock must always be | |
300 | * acquired first. | |
301 | */ | |
302 | static inline spinlock_t *rht_bucket_lock(const struct bucket_table *tbl, | |
303 | unsigned int hash) | |
304 | { | |
305 | return &tbl->locks[hash & tbl->locks_mask]; | |
306 | } | |
307 | ||
7e1e7763 | 308 | #ifdef CONFIG_PROVE_LOCKING |
97defe1e | 309 | int lockdep_rht_mutex_is_held(struct rhashtable *ht); |
88d6ed15 | 310 | int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash); |
7e1e7763 | 311 | #else |
97defe1e | 312 | static inline int lockdep_rht_mutex_is_held(struct rhashtable *ht) |
7e1e7763 TG |
313 | { |
314 | return 1; | |
315 | } | |
88d6ed15 TG |
316 | |
317 | static inline int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, | |
318 | u32 hash) | |
319 | { | |
320 | return 1; | |
321 | } | |
7e1e7763 TG |
322 | #endif /* CONFIG_PROVE_LOCKING */ |
323 | ||
488fb86e HX |
324 | int rhashtable_init(struct rhashtable *ht, |
325 | const struct rhashtable_params *params); | |
7e1e7763 | 326 | |
02fd97c3 HX |
327 | int rhashtable_insert_slow(struct rhashtable *ht, const void *key, |
328 | struct rhash_head *obj, | |
329 | struct bucket_table *old_tbl); | |
ccd57b1b | 330 | int rhashtable_insert_rehash(struct rhashtable *ht); |
7e1e7763 | 331 | |
f2dba9c6 HX |
332 | int rhashtable_walk_init(struct rhashtable *ht, struct rhashtable_iter *iter); |
333 | void rhashtable_walk_exit(struct rhashtable_iter *iter); | |
334 | int rhashtable_walk_start(struct rhashtable_iter *iter) __acquires(RCU); | |
335 | void *rhashtable_walk_next(struct rhashtable_iter *iter); | |
336 | void rhashtable_walk_stop(struct rhashtable_iter *iter) __releases(RCU); | |
337 | ||
6b6f302c TG |
338 | void rhashtable_free_and_destroy(struct rhashtable *ht, |
339 | void (*free_fn)(void *ptr, void *arg), | |
340 | void *arg); | |
97defe1e | 341 | void rhashtable_destroy(struct rhashtable *ht); |
7e1e7763 TG |
342 | |
343 | #define rht_dereference(p, ht) \ | |
344 | rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht)) | |
345 | ||
346 | #define rht_dereference_rcu(p, ht) \ | |
347 | rcu_dereference_check(p, lockdep_rht_mutex_is_held(ht)) | |
348 | ||
88d6ed15 TG |
349 | #define rht_dereference_bucket(p, tbl, hash) \ |
350 | rcu_dereference_protected(p, lockdep_rht_bucket_is_held(tbl, hash)) | |
7e1e7763 | 351 | |
88d6ed15 TG |
352 | #define rht_dereference_bucket_rcu(p, tbl, hash) \ |
353 | rcu_dereference_check(p, lockdep_rht_bucket_is_held(tbl, hash)) | |
354 | ||
355 | #define rht_entry(tpos, pos, member) \ | |
356 | ({ tpos = container_of(pos, typeof(*tpos), member); 1; }) | |
7e1e7763 TG |
357 | |
358 | /** | |
88d6ed15 TG |
359 | * rht_for_each_continue - continue iterating over hash chain |
360 | * @pos: the &struct rhash_head to use as a loop cursor. | |
361 | * @head: the previous &struct rhash_head to continue from | |
362 | * @tbl: the &struct bucket_table | |
363 | * @hash: the hash value / bucket index | |
7e1e7763 | 364 | */ |
88d6ed15 TG |
365 | #define rht_for_each_continue(pos, head, tbl, hash) \ |
366 | for (pos = rht_dereference_bucket(head, tbl, hash); \ | |
f89bd6f8 | 367 | !rht_is_a_nulls(pos); \ |
88d6ed15 TG |
368 | pos = rht_dereference_bucket((pos)->next, tbl, hash)) |
369 | ||
370 | /** | |
371 | * rht_for_each - iterate over hash chain | |
372 | * @pos: the &struct rhash_head to use as a loop cursor. | |
373 | * @tbl: the &struct bucket_table | |
374 | * @hash: the hash value / bucket index | |
375 | */ | |
376 | #define rht_for_each(pos, tbl, hash) \ | |
377 | rht_for_each_continue(pos, (tbl)->buckets[hash], tbl, hash) | |
378 | ||
379 | /** | |
380 | * rht_for_each_entry_continue - continue iterating over hash chain | |
381 | * @tpos: the type * to use as a loop cursor. | |
382 | * @pos: the &struct rhash_head to use as a loop cursor. | |
383 | * @head: the previous &struct rhash_head to continue from | |
384 | * @tbl: the &struct bucket_table | |
385 | * @hash: the hash value / bucket index | |
386 | * @member: name of the &struct rhash_head within the hashable struct. | |
387 | */ | |
388 | #define rht_for_each_entry_continue(tpos, pos, head, tbl, hash, member) \ | |
389 | for (pos = rht_dereference_bucket(head, tbl, hash); \ | |
f89bd6f8 | 390 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \ |
88d6ed15 | 391 | pos = rht_dereference_bucket((pos)->next, tbl, hash)) |
7e1e7763 TG |
392 | |
393 | /** | |
394 | * rht_for_each_entry - iterate over hash chain of given type | |
88d6ed15 TG |
395 | * @tpos: the type * to use as a loop cursor. |
396 | * @pos: the &struct rhash_head to use as a loop cursor. | |
397 | * @tbl: the &struct bucket_table | |
398 | * @hash: the hash value / bucket index | |
399 | * @member: name of the &struct rhash_head within the hashable struct. | |
7e1e7763 | 400 | */ |
88d6ed15 TG |
401 | #define rht_for_each_entry(tpos, pos, tbl, hash, member) \ |
402 | rht_for_each_entry_continue(tpos, pos, (tbl)->buckets[hash], \ | |
403 | tbl, hash, member) | |
7e1e7763 TG |
404 | |
405 | /** | |
406 | * rht_for_each_entry_safe - safely iterate over hash chain of given type | |
88d6ed15 TG |
407 | * @tpos: the type * to use as a loop cursor. |
408 | * @pos: the &struct rhash_head to use as a loop cursor. | |
409 | * @next: the &struct rhash_head to use as next in loop cursor. | |
410 | * @tbl: the &struct bucket_table | |
411 | * @hash: the hash value / bucket index | |
412 | * @member: name of the &struct rhash_head within the hashable struct. | |
7e1e7763 TG |
413 | * |
414 | * This hash chain list-traversal primitive allows for the looped code to | |
415 | * remove the loop cursor from the list. | |
416 | */ | |
88d6ed15 TG |
417 | #define rht_for_each_entry_safe(tpos, pos, next, tbl, hash, member) \ |
418 | for (pos = rht_dereference_bucket((tbl)->buckets[hash], tbl, hash), \ | |
f89bd6f8 TG |
419 | next = !rht_is_a_nulls(pos) ? \ |
420 | rht_dereference_bucket(pos->next, tbl, hash) : NULL; \ | |
421 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \ | |
607954b0 PM |
422 | pos = next, \ |
423 | next = !rht_is_a_nulls(pos) ? \ | |
424 | rht_dereference_bucket(pos->next, tbl, hash) : NULL) | |
88d6ed15 TG |
425 | |
426 | /** | |
427 | * rht_for_each_rcu_continue - continue iterating over rcu hash chain | |
428 | * @pos: the &struct rhash_head to use as a loop cursor. | |
429 | * @head: the previous &struct rhash_head to continue from | |
430 | * @tbl: the &struct bucket_table | |
431 | * @hash: the hash value / bucket index | |
432 | * | |
433 | * This hash chain list-traversal primitive may safely run concurrently with | |
434 | * the _rcu mutation primitives such as rhashtable_insert() as long as the | |
435 | * traversal is guarded by rcu_read_lock(). | |
436 | */ | |
437 | #define rht_for_each_rcu_continue(pos, head, tbl, hash) \ | |
438 | for (({barrier(); }), \ | |
439 | pos = rht_dereference_bucket_rcu(head, tbl, hash); \ | |
f89bd6f8 | 440 | !rht_is_a_nulls(pos); \ |
88d6ed15 | 441 | pos = rcu_dereference_raw(pos->next)) |
7e1e7763 TG |
442 | |
443 | /** | |
444 | * rht_for_each_rcu - iterate over rcu hash chain | |
88d6ed15 TG |
445 | * @pos: the &struct rhash_head to use as a loop cursor. |
446 | * @tbl: the &struct bucket_table | |
447 | * @hash: the hash value / bucket index | |
7e1e7763 TG |
448 | * |
449 | * This hash chain list-traversal primitive may safely run concurrently with | |
88d6ed15 | 450 | * the _rcu mutation primitives such as rhashtable_insert() as long as the |
7e1e7763 TG |
451 | * traversal is guarded by rcu_read_lock(). |
452 | */ | |
88d6ed15 TG |
453 | #define rht_for_each_rcu(pos, tbl, hash) \ |
454 | rht_for_each_rcu_continue(pos, (tbl)->buckets[hash], tbl, hash) | |
455 | ||
456 | /** | |
457 | * rht_for_each_entry_rcu_continue - continue iterating over rcu hash chain | |
458 | * @tpos: the type * to use as a loop cursor. | |
459 | * @pos: the &struct rhash_head to use as a loop cursor. | |
460 | * @head: the previous &struct rhash_head to continue from | |
461 | * @tbl: the &struct bucket_table | |
462 | * @hash: the hash value / bucket index | |
463 | * @member: name of the &struct rhash_head within the hashable struct. | |
464 | * | |
465 | * This hash chain list-traversal primitive may safely run concurrently with | |
466 | * the _rcu mutation primitives such as rhashtable_insert() as long as the | |
467 | * traversal is guarded by rcu_read_lock(). | |
468 | */ | |
469 | #define rht_for_each_entry_rcu_continue(tpos, pos, head, tbl, hash, member) \ | |
470 | for (({barrier(); }), \ | |
471 | pos = rht_dereference_bucket_rcu(head, tbl, hash); \ | |
f89bd6f8 | 472 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \ |
88d6ed15 | 473 | pos = rht_dereference_bucket_rcu(pos->next, tbl, hash)) |
7e1e7763 TG |
474 | |
475 | /** | |
476 | * rht_for_each_entry_rcu - iterate over rcu hash chain of given type | |
88d6ed15 TG |
477 | * @tpos: the type * to use as a loop cursor. |
478 | * @pos: the &struct rhash_head to use as a loop cursor. | |
479 | * @tbl: the &struct bucket_table | |
480 | * @hash: the hash value / bucket index | |
481 | * @member: name of the &struct rhash_head within the hashable struct. | |
7e1e7763 TG |
482 | * |
483 | * This hash chain list-traversal primitive may safely run concurrently with | |
88d6ed15 | 484 | * the _rcu mutation primitives such as rhashtable_insert() as long as the |
7e1e7763 TG |
485 | * traversal is guarded by rcu_read_lock(). |
486 | */ | |
88d6ed15 TG |
487 | #define rht_for_each_entry_rcu(tpos, pos, tbl, hash, member) \ |
488 | rht_for_each_entry_rcu_continue(tpos, pos, (tbl)->buckets[hash],\ | |
489 | tbl, hash, member) | |
7e1e7763 | 490 | |
02fd97c3 HX |
491 | static inline int rhashtable_compare(struct rhashtable_compare_arg *arg, |
492 | const void *obj) | |
493 | { | |
494 | struct rhashtable *ht = arg->ht; | |
495 | const char *ptr = obj; | |
496 | ||
497 | return memcmp(ptr + ht->p.key_offset, arg->key, ht->p.key_len); | |
498 | } | |
499 | ||
500 | /** | |
501 | * rhashtable_lookup_fast - search hash table, inlined version | |
502 | * @ht: hash table | |
503 | * @key: the pointer to the key | |
504 | * @params: hash table parameters | |
505 | * | |
506 | * Computes the hash value for the key and traverses the bucket chain looking | |
507 | * for a entry with an identical key. The first matching entry is returned. | |
508 | * | |
509 | * Returns the first entry on which the compare function returned true. | |
510 | */ | |
511 | static inline void *rhashtable_lookup_fast( | |
512 | struct rhashtable *ht, const void *key, | |
513 | const struct rhashtable_params params) | |
514 | { | |
515 | struct rhashtable_compare_arg arg = { | |
516 | .ht = ht, | |
517 | .key = key, | |
518 | }; | |
519 | const struct bucket_table *tbl; | |
520 | struct rhash_head *he; | |
299e5c32 | 521 | unsigned int hash; |
02fd97c3 HX |
522 | |
523 | rcu_read_lock(); | |
524 | ||
525 | tbl = rht_dereference_rcu(ht->tbl, ht); | |
526 | restart: | |
527 | hash = rht_key_hashfn(ht, tbl, key, params); | |
528 | rht_for_each_rcu(he, tbl, hash) { | |
529 | if (params.obj_cmpfn ? | |
530 | params.obj_cmpfn(&arg, rht_obj(ht, he)) : | |
531 | rhashtable_compare(&arg, rht_obj(ht, he))) | |
532 | continue; | |
533 | rcu_read_unlock(); | |
534 | return rht_obj(ht, he); | |
535 | } | |
536 | ||
537 | /* Ensure we see any new tables. */ | |
538 | smp_rmb(); | |
539 | ||
540 | tbl = rht_dereference_rcu(tbl->future_tbl, ht); | |
541 | if (unlikely(tbl)) | |
542 | goto restart; | |
543 | rcu_read_unlock(); | |
544 | ||
545 | return NULL; | |
546 | } | |
547 | ||
ac833bdd | 548 | /* Internal function, please use rhashtable_insert_fast() instead */ |
02fd97c3 HX |
549 | static inline int __rhashtable_insert_fast( |
550 | struct rhashtable *ht, const void *key, struct rhash_head *obj, | |
551 | const struct rhashtable_params params) | |
552 | { | |
553 | struct rhashtable_compare_arg arg = { | |
554 | .ht = ht, | |
555 | .key = key, | |
556 | }; | |
02fd97c3 HX |
557 | struct bucket_table *tbl, *new_tbl; |
558 | struct rhash_head *head; | |
559 | spinlock_t *lock; | |
299e5c32 TG |
560 | unsigned int elasticity; |
561 | unsigned int hash; | |
ccd57b1b | 562 | int err; |
02fd97c3 | 563 | |
ccd57b1b | 564 | restart: |
02fd97c3 HX |
565 | rcu_read_lock(); |
566 | ||
567 | tbl = rht_dereference_rcu(ht->tbl, ht); | |
02fd97c3 | 568 | |
b824478b HX |
569 | /* All insertions must grab the oldest table containing |
570 | * the hashed bucket that is yet to be rehashed. | |
02fd97c3 | 571 | */ |
b824478b HX |
572 | for (;;) { |
573 | hash = rht_head_hashfn(ht, tbl, obj, params); | |
574 | lock = rht_bucket_lock(tbl, hash); | |
575 | spin_lock_bh(lock); | |
576 | ||
577 | if (tbl->rehash <= hash) | |
578 | break; | |
579 | ||
580 | spin_unlock_bh(lock); | |
581 | tbl = rht_dereference_rcu(tbl->future_tbl, ht); | |
582 | } | |
583 | ||
02fd97c3 HX |
584 | new_tbl = rht_dereference_rcu(tbl->future_tbl, ht); |
585 | if (unlikely(new_tbl)) { | |
586 | err = rhashtable_insert_slow(ht, key, obj, new_tbl); | |
ccd57b1b HX |
587 | if (err == -EAGAIN) |
588 | goto slow_path; | |
02fd97c3 HX |
589 | goto out; |
590 | } | |
591 | ||
ccd57b1b HX |
592 | if (unlikely(rht_grow_above_100(ht, tbl))) { |
593 | slow_path: | |
594 | spin_unlock_bh(lock); | |
ccd57b1b | 595 | err = rhashtable_insert_rehash(ht); |
58be8a58 | 596 | rcu_read_unlock(); |
ccd57b1b HX |
597 | if (err) |
598 | return err; | |
599 | ||
600 | goto restart; | |
601 | } | |
02fd97c3 | 602 | |
ccd57b1b HX |
603 | err = -EEXIST; |
604 | elasticity = ht->elasticity; | |
02fd97c3 | 605 | rht_for_each(head, tbl, hash) { |
ccd57b1b HX |
606 | if (key && |
607 | unlikely(!(params.obj_cmpfn ? | |
02fd97c3 HX |
608 | params.obj_cmpfn(&arg, rht_obj(ht, head)) : |
609 | rhashtable_compare(&arg, rht_obj(ht, head))))) | |
610 | goto out; | |
ccd57b1b HX |
611 | if (!--elasticity) |
612 | goto slow_path; | |
02fd97c3 HX |
613 | } |
614 | ||
02fd97c3 HX |
615 | err = 0; |
616 | ||
617 | head = rht_dereference_bucket(tbl->buckets[hash], tbl, hash); | |
618 | ||
619 | RCU_INIT_POINTER(obj->next, head); | |
620 | ||
621 | rcu_assign_pointer(tbl->buckets[hash], obj); | |
622 | ||
623 | atomic_inc(&ht->nelems); | |
624 | if (rht_grow_above_75(ht, tbl)) | |
625 | schedule_work(&ht->run_work); | |
626 | ||
627 | out: | |
628 | spin_unlock_bh(lock); | |
629 | rcu_read_unlock(); | |
630 | ||
631 | return err; | |
632 | } | |
633 | ||
634 | /** | |
635 | * rhashtable_insert_fast - insert object into hash table | |
636 | * @ht: hash table | |
637 | * @obj: pointer to hash head inside object | |
638 | * @params: hash table parameters | |
639 | * | |
640 | * Will take a per bucket spinlock to protect against mutual mutations | |
641 | * on the same bucket. Multiple insertions may occur in parallel unless | |
642 | * they map to the same bucket lock. | |
643 | * | |
644 | * It is safe to call this function from atomic context. | |
645 | * | |
646 | * Will trigger an automatic deferred table resizing if the size grows | |
647 | * beyond the watermark indicated by grow_decision() which can be passed | |
648 | * to rhashtable_init(). | |
649 | */ | |
650 | static inline int rhashtable_insert_fast( | |
651 | struct rhashtable *ht, struct rhash_head *obj, | |
652 | const struct rhashtable_params params) | |
653 | { | |
654 | return __rhashtable_insert_fast(ht, NULL, obj, params); | |
655 | } | |
656 | ||
657 | /** | |
658 | * rhashtable_lookup_insert_fast - lookup and insert object into hash table | |
659 | * @ht: hash table | |
660 | * @obj: pointer to hash head inside object | |
661 | * @params: hash table parameters | |
662 | * | |
663 | * Locks down the bucket chain in both the old and new table if a resize | |
664 | * is in progress to ensure that writers can't remove from the old table | |
665 | * and can't insert to the new table during the atomic operation of search | |
666 | * and insertion. Searches for duplicates in both the old and new table if | |
667 | * a resize is in progress. | |
668 | * | |
669 | * This lookup function may only be used for fixed key hash table (key_len | |
670 | * parameter set). It will BUG() if used inappropriately. | |
671 | * | |
672 | * It is safe to call this function from atomic context. | |
673 | * | |
674 | * Will trigger an automatic deferred table resizing if the size grows | |
675 | * beyond the watermark indicated by grow_decision() which can be passed | |
676 | * to rhashtable_init(). | |
677 | */ | |
678 | static inline int rhashtable_lookup_insert_fast( | |
679 | struct rhashtable *ht, struct rhash_head *obj, | |
680 | const struct rhashtable_params params) | |
681 | { | |
682 | const char *key = rht_obj(ht, obj); | |
683 | ||
684 | BUG_ON(ht->p.obj_hashfn); | |
685 | ||
686 | return __rhashtable_insert_fast(ht, key + ht->p.key_offset, obj, | |
687 | params); | |
688 | } | |
689 | ||
690 | /** | |
691 | * rhashtable_lookup_insert_key - search and insert object to hash table | |
692 | * with explicit key | |
693 | * @ht: hash table | |
694 | * @key: key | |
695 | * @obj: pointer to hash head inside object | |
696 | * @params: hash table parameters | |
697 | * | |
698 | * Locks down the bucket chain in both the old and new table if a resize | |
699 | * is in progress to ensure that writers can't remove from the old table | |
700 | * and can't insert to the new table during the atomic operation of search | |
701 | * and insertion. Searches for duplicates in both the old and new table if | |
702 | * a resize is in progress. | |
703 | * | |
704 | * Lookups may occur in parallel with hashtable mutations and resizing. | |
705 | * | |
706 | * Will trigger an automatic deferred table resizing if the size grows | |
707 | * beyond the watermark indicated by grow_decision() which can be passed | |
708 | * to rhashtable_init(). | |
709 | * | |
710 | * Returns zero on success. | |
711 | */ | |
712 | static inline int rhashtable_lookup_insert_key( | |
713 | struct rhashtable *ht, const void *key, struct rhash_head *obj, | |
714 | const struct rhashtable_params params) | |
715 | { | |
716 | BUG_ON(!ht->p.obj_hashfn || !key); | |
717 | ||
718 | return __rhashtable_insert_fast(ht, key, obj, params); | |
719 | } | |
720 | ||
ac833bdd | 721 | /* Internal function, please use rhashtable_remove_fast() instead */ |
02fd97c3 HX |
722 | static inline int __rhashtable_remove_fast( |
723 | struct rhashtable *ht, struct bucket_table *tbl, | |
724 | struct rhash_head *obj, const struct rhashtable_params params) | |
725 | { | |
726 | struct rhash_head __rcu **pprev; | |
727 | struct rhash_head *he; | |
728 | spinlock_t * lock; | |
299e5c32 | 729 | unsigned int hash; |
02fd97c3 HX |
730 | int err = -ENOENT; |
731 | ||
732 | hash = rht_head_hashfn(ht, tbl, obj, params); | |
733 | lock = rht_bucket_lock(tbl, hash); | |
734 | ||
735 | spin_lock_bh(lock); | |
736 | ||
737 | pprev = &tbl->buckets[hash]; | |
738 | rht_for_each(he, tbl, hash) { | |
739 | if (he != obj) { | |
740 | pprev = &he->next; | |
741 | continue; | |
742 | } | |
743 | ||
744 | rcu_assign_pointer(*pprev, obj->next); | |
745 | err = 0; | |
746 | break; | |
747 | } | |
748 | ||
749 | spin_unlock_bh(lock); | |
750 | ||
751 | return err; | |
752 | } | |
753 | ||
754 | /** | |
755 | * rhashtable_remove_fast - remove object from hash table | |
756 | * @ht: hash table | |
757 | * @obj: pointer to hash head inside object | |
758 | * @params: hash table parameters | |
759 | * | |
760 | * Since the hash chain is single linked, the removal operation needs to | |
761 | * walk the bucket chain upon removal. The removal operation is thus | |
762 | * considerable slow if the hash table is not correctly sized. | |
763 | * | |
764 | * Will automatically shrink the table via rhashtable_expand() if the | |
765 | * shrink_decision function specified at rhashtable_init() returns true. | |
766 | * | |
767 | * Returns zero on success, -ENOENT if the entry could not be found. | |
768 | */ | |
769 | static inline int rhashtable_remove_fast( | |
770 | struct rhashtable *ht, struct rhash_head *obj, | |
771 | const struct rhashtable_params params) | |
772 | { | |
773 | struct bucket_table *tbl; | |
774 | int err; | |
775 | ||
776 | rcu_read_lock(); | |
777 | ||
778 | tbl = rht_dereference_rcu(ht->tbl, ht); | |
779 | ||
780 | /* Because we have already taken (and released) the bucket | |
781 | * lock in old_tbl, if we find that future_tbl is not yet | |
782 | * visible then that guarantees the entry to still be in | |
783 | * the old tbl if it exists. | |
784 | */ | |
785 | while ((err = __rhashtable_remove_fast(ht, tbl, obj, params)) && | |
786 | (tbl = rht_dereference_rcu(tbl->future_tbl, ht))) | |
787 | ; | |
788 | ||
789 | if (err) | |
790 | goto out; | |
791 | ||
792 | atomic_dec(&ht->nelems); | |
b5e2c150 TG |
793 | if (unlikely(ht->p.automatic_shrinking && |
794 | rht_shrink_below_30(ht, tbl))) | |
02fd97c3 HX |
795 | schedule_work(&ht->run_work); |
796 | ||
797 | out: | |
798 | rcu_read_unlock(); | |
799 | ||
800 | return err; | |
801 | } | |
802 | ||
7e1e7763 | 803 | #endif /* _LINUX_RHASHTABLE_H */ |