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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 | ||
07ee0722 | 20 | #include <linux/atomic.h> |
f2dba9c6 | 21 | #include <linux/compiler.h> |
6626af69 | 22 | #include <linux/errno.h> |
31ccde2d | 23 | #include <linux/jhash.h> |
f89bd6f8 | 24 | #include <linux/list_nulls.h> |
97defe1e | 25 | #include <linux/workqueue.h> |
86b35b64 | 26 | #include <linux/mutex.h> |
02fd97c3 | 27 | #include <linux/rcupdate.h> |
7e1e7763 | 28 | |
f89bd6f8 TG |
29 | /* |
30 | * The end of the chain is marked with a special nulls marks which has | |
31 | * the following format: | |
32 | * | |
33 | * +-------+-----------------------------------------------------+-+ | |
34 | * | Base | Hash |1| | |
35 | * +-------+-----------------------------------------------------+-+ | |
36 | * | |
37 | * Base (4 bits) : Reserved to distinguish between multiple tables. | |
38 | * Specified via &struct rhashtable_params.nulls_base. | |
39 | * Hash (27 bits): Full hash (unmasked) of first element added to bucket | |
40 | * 1 (1 bit) : Nulls marker (always set) | |
41 | * | |
42 | * The remaining bits of the next pointer remain unused for now. | |
43 | */ | |
44 | #define RHT_BASE_BITS 4 | |
45 | #define RHT_HASH_BITS 27 | |
46 | #define RHT_BASE_SHIFT RHT_HASH_BITS | |
47 | ||
02fd97c3 HX |
48 | /* Base bits plus 1 bit for nulls marker */ |
49 | #define RHT_HASH_RESERVED_SPACE (RHT_BASE_BITS + 1) | |
50 | ||
7e1e7763 | 51 | struct rhash_head { |
5300fdcb | 52 | struct rhash_head __rcu *next; |
7e1e7763 TG |
53 | }; |
54 | ||
97defe1e TG |
55 | /** |
56 | * struct bucket_table - Table of hash buckets | |
57 | * @size: Number of hash buckets | |
63d512d0 | 58 | * @rehash: Current bucket being rehashed |
988dfbd7 | 59 | * @hash_rnd: Random seed to fold into hash |
97defe1e TG |
60 | * @locks_mask: Mask to apply before accessing locks[] |
61 | * @locks: Array of spinlocks protecting individual buckets | |
eddee5ba | 62 | * @walkers: List of active walkers |
9d901bc0 | 63 | * @rcu: RCU structure for freeing the table |
c4db8848 | 64 | * @future_tbl: Table under construction during rehashing |
97defe1e TG |
65 | * @buckets: size * hash buckets |
66 | */ | |
7e1e7763 | 67 | struct bucket_table { |
63d512d0 HX |
68 | unsigned int size; |
69 | unsigned int rehash; | |
988dfbd7 | 70 | u32 hash_rnd; |
b9ebafbe ED |
71 | unsigned int locks_mask; |
72 | spinlock_t *locks; | |
eddee5ba | 73 | struct list_head walkers; |
9d901bc0 | 74 | struct rcu_head rcu; |
b9ebafbe | 75 | |
c4db8848 HX |
76 | struct bucket_table __rcu *future_tbl; |
77 | ||
b9ebafbe | 78 | struct rhash_head __rcu *buckets[] ____cacheline_aligned_in_smp; |
7e1e7763 TG |
79 | }; |
80 | ||
02fd97c3 HX |
81 | /** |
82 | * struct rhashtable_compare_arg - Key for the function rhashtable_compare | |
83 | * @ht: Hash table | |
84 | * @key: Key to compare against | |
85 | */ | |
86 | struct rhashtable_compare_arg { | |
87 | struct rhashtable *ht; | |
88 | const void *key; | |
89 | }; | |
90 | ||
7e1e7763 | 91 | typedef u32 (*rht_hashfn_t)(const void *data, u32 len, u32 seed); |
49f7b33e | 92 | typedef u32 (*rht_obj_hashfn_t)(const void *data, u32 len, u32 seed); |
02fd97c3 HX |
93 | typedef int (*rht_obj_cmpfn_t)(struct rhashtable_compare_arg *arg, |
94 | const void *obj); | |
7e1e7763 TG |
95 | |
96 | struct rhashtable; | |
97 | ||
98 | /** | |
99 | * struct rhashtable_params - Hash table construction parameters | |
100 | * @nelem_hint: Hint on number of elements, should be 75% of desired size | |
101 | * @key_len: Length of key | |
102 | * @key_offset: Offset of key in struct to be hashed | |
103 | * @head_offset: Offset of rhash_head in struct to be hashed | |
07ee0722 | 104 | * @insecure_max_entries: Maximum number of entries (may be exceeded) |
c2e213cf HX |
105 | * @max_size: Maximum size while expanding |
106 | * @min_size: Minimum size while shrinking | |
f89bd6f8 | 107 | * @nulls_base: Base value to generate nulls marker |
ccd57b1b | 108 | * @insecure_elasticity: Set to true to disable chain length checks |
b5e2c150 | 109 | * @automatic_shrinking: Enable automatic shrinking of tables |
97defe1e | 110 | * @locks_mul: Number of bucket locks to allocate per cpu (default: 128) |
31ccde2d | 111 | * @hashfn: Hash function (default: jhash2 if !(key_len % 4), or jhash) |
7e1e7763 | 112 | * @obj_hashfn: Function to hash object |
02fd97c3 | 113 | * @obj_cmpfn: Function to compare key with object |
7e1e7763 TG |
114 | */ |
115 | struct rhashtable_params { | |
116 | size_t nelem_hint; | |
117 | size_t key_len; | |
118 | size_t key_offset; | |
119 | size_t head_offset; | |
07ee0722 | 120 | unsigned int insecure_max_entries; |
c2e213cf HX |
121 | unsigned int max_size; |
122 | unsigned int min_size; | |
f89bd6f8 | 123 | u32 nulls_base; |
ccd57b1b | 124 | bool insecure_elasticity; |
b5e2c150 | 125 | bool automatic_shrinking; |
97defe1e | 126 | size_t locks_mul; |
7e1e7763 TG |
127 | rht_hashfn_t hashfn; |
128 | rht_obj_hashfn_t obj_hashfn; | |
02fd97c3 | 129 | rht_obj_cmpfn_t obj_cmpfn; |
7e1e7763 TG |
130 | }; |
131 | ||
132 | /** | |
133 | * struct rhashtable - Hash table handle | |
134 | * @tbl: Bucket table | |
135 | * @nelems: Number of elements in table | |
31ccde2d | 136 | * @key_len: Key length for hashfn |
ccd57b1b | 137 | * @elasticity: Maximum chain length before rehash |
7e1e7763 | 138 | * @p: Configuration parameters |
97defe1e TG |
139 | * @run_work: Deferred worker to expand/shrink asynchronously |
140 | * @mutex: Mutex to protect current/future table swapping | |
ba7c95ea | 141 | * @lock: Spin lock to protect walker list |
7e1e7763 TG |
142 | */ |
143 | struct rhashtable { | |
144 | struct bucket_table __rcu *tbl; | |
97defe1e | 145 | atomic_t nelems; |
31ccde2d | 146 | unsigned int key_len; |
ccd57b1b | 147 | unsigned int elasticity; |
7e1e7763 | 148 | struct rhashtable_params p; |
57699a40 | 149 | struct work_struct run_work; |
97defe1e | 150 | struct mutex mutex; |
ba7c95ea | 151 | spinlock_t lock; |
7e1e7763 TG |
152 | }; |
153 | ||
f2dba9c6 HX |
154 | /** |
155 | * struct rhashtable_walker - Hash table walker | |
156 | * @list: List entry on list of walkers | |
eddee5ba | 157 | * @tbl: The table that we were walking over |
f2dba9c6 HX |
158 | */ |
159 | struct rhashtable_walker { | |
160 | struct list_head list; | |
eddee5ba | 161 | struct bucket_table *tbl; |
f2dba9c6 HX |
162 | }; |
163 | ||
164 | /** | |
165 | * struct rhashtable_iter - Hash table iterator, fits into netlink cb | |
166 | * @ht: Table to iterate through | |
167 | * @p: Current pointer | |
168 | * @walker: Associated rhashtable walker | |
169 | * @slot: Current slot | |
170 | * @skip: Number of entries to skip in slot | |
171 | */ | |
172 | struct rhashtable_iter { | |
173 | struct rhashtable *ht; | |
174 | struct rhash_head *p; | |
175 | struct rhashtable_walker *walker; | |
176 | unsigned int slot; | |
177 | unsigned int skip; | |
178 | }; | |
179 | ||
f89bd6f8 TG |
180 | static inline unsigned long rht_marker(const struct rhashtable *ht, u32 hash) |
181 | { | |
182 | return NULLS_MARKER(ht->p.nulls_base + hash); | |
183 | } | |
184 | ||
185 | #define INIT_RHT_NULLS_HEAD(ptr, ht, hash) \ | |
186 | ((ptr) = (typeof(ptr)) rht_marker(ht, hash)) | |
187 | ||
188 | static inline bool rht_is_a_nulls(const struct rhash_head *ptr) | |
189 | { | |
190 | return ((unsigned long) ptr & 1); | |
191 | } | |
192 | ||
193 | static inline unsigned long rht_get_nulls_value(const struct rhash_head *ptr) | |
194 | { | |
195 | return ((unsigned long) ptr) >> 1; | |
196 | } | |
197 | ||
02fd97c3 HX |
198 | static inline void *rht_obj(const struct rhashtable *ht, |
199 | const struct rhash_head *he) | |
200 | { | |
201 | return (char *)he - ht->p.head_offset; | |
202 | } | |
203 | ||
204 | static inline unsigned int rht_bucket_index(const struct bucket_table *tbl, | |
205 | unsigned int hash) | |
206 | { | |
207 | return (hash >> RHT_HASH_RESERVED_SPACE) & (tbl->size - 1); | |
208 | } | |
209 | ||
210 | static inline unsigned int rht_key_hashfn( | |
211 | struct rhashtable *ht, const struct bucket_table *tbl, | |
212 | const void *key, const struct rhashtable_params params) | |
213 | { | |
299e5c32 | 214 | unsigned int hash; |
de91b25c | 215 | |
31ccde2d HX |
216 | /* params must be equal to ht->p if it isn't constant. */ |
217 | if (!__builtin_constant_p(params.key_len)) | |
218 | hash = ht->p.hashfn(key, ht->key_len, tbl->hash_rnd); | |
219 | else if (params.key_len) { | |
299e5c32 | 220 | unsigned int key_len = params.key_len; |
31ccde2d HX |
221 | |
222 | if (params.hashfn) | |
223 | hash = params.hashfn(key, key_len, tbl->hash_rnd); | |
224 | else if (key_len & (sizeof(u32) - 1)) | |
225 | hash = jhash(key, key_len, tbl->hash_rnd); | |
226 | else | |
227 | hash = jhash2(key, key_len / sizeof(u32), | |
228 | tbl->hash_rnd); | |
229 | } else { | |
299e5c32 | 230 | unsigned int key_len = ht->p.key_len; |
31ccde2d HX |
231 | |
232 | if (params.hashfn) | |
233 | hash = params.hashfn(key, key_len, tbl->hash_rnd); | |
234 | else | |
235 | hash = jhash(key, key_len, tbl->hash_rnd); | |
236 | } | |
237 | ||
238 | return rht_bucket_index(tbl, hash); | |
02fd97c3 HX |
239 | } |
240 | ||
241 | static inline unsigned int rht_head_hashfn( | |
242 | struct rhashtable *ht, const struct bucket_table *tbl, | |
243 | const struct rhash_head *he, const struct rhashtable_params params) | |
244 | { | |
245 | const char *ptr = rht_obj(ht, he); | |
246 | ||
247 | return likely(params.obj_hashfn) ? | |
49f7b33e PM |
248 | rht_bucket_index(tbl, params.obj_hashfn(ptr, params.key_len ?: |
249 | ht->p.key_len, | |
250 | tbl->hash_rnd)) : | |
02fd97c3 HX |
251 | rht_key_hashfn(ht, tbl, ptr + params.key_offset, params); |
252 | } | |
253 | ||
254 | /** | |
255 | * rht_grow_above_75 - returns true if nelems > 0.75 * table-size | |
256 | * @ht: hash table | |
257 | * @tbl: current table | |
258 | */ | |
259 | static inline bool rht_grow_above_75(const struct rhashtable *ht, | |
260 | const struct bucket_table *tbl) | |
261 | { | |
262 | /* Expand table when exceeding 75% load */ | |
263 | return atomic_read(&ht->nelems) > (tbl->size / 4 * 3) && | |
264 | (!ht->p.max_size || tbl->size < ht->p.max_size); | |
265 | } | |
266 | ||
267 | /** | |
268 | * rht_shrink_below_30 - returns true if nelems < 0.3 * table-size | |
269 | * @ht: hash table | |
270 | * @tbl: current table | |
271 | */ | |
272 | static inline bool rht_shrink_below_30(const struct rhashtable *ht, | |
273 | const struct bucket_table *tbl) | |
274 | { | |
275 | /* Shrink table beneath 30% load */ | |
276 | return atomic_read(&ht->nelems) < (tbl->size * 3 / 10) && | |
277 | tbl->size > ht->p.min_size; | |
278 | } | |
279 | ||
ccd57b1b HX |
280 | /** |
281 | * rht_grow_above_100 - returns true if nelems > table-size | |
282 | * @ht: hash table | |
283 | * @tbl: current table | |
284 | */ | |
285 | static inline bool rht_grow_above_100(const struct rhashtable *ht, | |
286 | const struct bucket_table *tbl) | |
287 | { | |
1d8dc3d3 JB |
288 | return atomic_read(&ht->nelems) > tbl->size && |
289 | (!ht->p.max_size || tbl->size < ht->p.max_size); | |
ccd57b1b HX |
290 | } |
291 | ||
07ee0722 HX |
292 | /** |
293 | * rht_grow_above_max - returns true if table is above maximum | |
294 | * @ht: hash table | |
295 | * @tbl: current table | |
296 | */ | |
297 | static inline bool rht_grow_above_max(const struct rhashtable *ht, | |
298 | const struct bucket_table *tbl) | |
299 | { | |
300 | return ht->p.insecure_max_entries && | |
301 | atomic_read(&ht->nelems) >= ht->p.insecure_max_entries; | |
302 | } | |
303 | ||
02fd97c3 HX |
304 | /* The bucket lock is selected based on the hash and protects mutations |
305 | * on a group of hash buckets. | |
306 | * | |
307 | * A maximum of tbl->size/2 bucket locks is allocated. This ensures that | |
308 | * a single lock always covers both buckets which may both contains | |
309 | * entries which link to the same bucket of the old table during resizing. | |
310 | * This allows to simplify the locking as locking the bucket in both | |
311 | * tables during resize always guarantee protection. | |
312 | * | |
313 | * IMPORTANT: When holding the bucket lock of both the old and new table | |
314 | * during expansions and shrinking, the old bucket lock must always be | |
315 | * acquired first. | |
316 | */ | |
317 | static inline spinlock_t *rht_bucket_lock(const struct bucket_table *tbl, | |
318 | unsigned int hash) | |
319 | { | |
320 | return &tbl->locks[hash & tbl->locks_mask]; | |
321 | } | |
322 | ||
7e1e7763 | 323 | #ifdef CONFIG_PROVE_LOCKING |
97defe1e | 324 | int lockdep_rht_mutex_is_held(struct rhashtable *ht); |
88d6ed15 | 325 | int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash); |
7e1e7763 | 326 | #else |
97defe1e | 327 | static inline int lockdep_rht_mutex_is_held(struct rhashtable *ht) |
7e1e7763 TG |
328 | { |
329 | return 1; | |
330 | } | |
88d6ed15 TG |
331 | |
332 | static inline int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, | |
333 | u32 hash) | |
334 | { | |
335 | return 1; | |
336 | } | |
7e1e7763 TG |
337 | #endif /* CONFIG_PROVE_LOCKING */ |
338 | ||
488fb86e HX |
339 | int rhashtable_init(struct rhashtable *ht, |
340 | const struct rhashtable_params *params); | |
7e1e7763 | 341 | |
02fd97c3 HX |
342 | int rhashtable_insert_slow(struct rhashtable *ht, const void *key, |
343 | struct rhash_head *obj, | |
344 | struct bucket_table *old_tbl); | |
ccd57b1b | 345 | int rhashtable_insert_rehash(struct rhashtable *ht); |
7e1e7763 | 346 | |
f2dba9c6 HX |
347 | int rhashtable_walk_init(struct rhashtable *ht, struct rhashtable_iter *iter); |
348 | void rhashtable_walk_exit(struct rhashtable_iter *iter); | |
349 | int rhashtable_walk_start(struct rhashtable_iter *iter) __acquires(RCU); | |
350 | void *rhashtable_walk_next(struct rhashtable_iter *iter); | |
351 | void rhashtable_walk_stop(struct rhashtable_iter *iter) __releases(RCU); | |
352 | ||
6b6f302c TG |
353 | void rhashtable_free_and_destroy(struct rhashtable *ht, |
354 | void (*free_fn)(void *ptr, void *arg), | |
355 | void *arg); | |
97defe1e | 356 | void rhashtable_destroy(struct rhashtable *ht); |
7e1e7763 TG |
357 | |
358 | #define rht_dereference(p, ht) \ | |
359 | rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht)) | |
360 | ||
361 | #define rht_dereference_rcu(p, ht) \ | |
362 | rcu_dereference_check(p, lockdep_rht_mutex_is_held(ht)) | |
363 | ||
88d6ed15 TG |
364 | #define rht_dereference_bucket(p, tbl, hash) \ |
365 | rcu_dereference_protected(p, lockdep_rht_bucket_is_held(tbl, hash)) | |
7e1e7763 | 366 | |
88d6ed15 TG |
367 | #define rht_dereference_bucket_rcu(p, tbl, hash) \ |
368 | rcu_dereference_check(p, lockdep_rht_bucket_is_held(tbl, hash)) | |
369 | ||
370 | #define rht_entry(tpos, pos, member) \ | |
371 | ({ tpos = container_of(pos, typeof(*tpos), member); 1; }) | |
7e1e7763 TG |
372 | |
373 | /** | |
88d6ed15 TG |
374 | * rht_for_each_continue - continue iterating over hash chain |
375 | * @pos: the &struct rhash_head to use as a loop cursor. | |
376 | * @head: the previous &struct rhash_head to continue from | |
377 | * @tbl: the &struct bucket_table | |
378 | * @hash: the hash value / bucket index | |
7e1e7763 | 379 | */ |
88d6ed15 TG |
380 | #define rht_for_each_continue(pos, head, tbl, hash) \ |
381 | for (pos = rht_dereference_bucket(head, tbl, hash); \ | |
f89bd6f8 | 382 | !rht_is_a_nulls(pos); \ |
88d6ed15 TG |
383 | pos = rht_dereference_bucket((pos)->next, tbl, hash)) |
384 | ||
385 | /** | |
386 | * rht_for_each - iterate over hash chain | |
387 | * @pos: the &struct rhash_head to use as a loop cursor. | |
388 | * @tbl: the &struct bucket_table | |
389 | * @hash: the hash value / bucket index | |
390 | */ | |
391 | #define rht_for_each(pos, tbl, hash) \ | |
392 | rht_for_each_continue(pos, (tbl)->buckets[hash], tbl, hash) | |
393 | ||
394 | /** | |
395 | * rht_for_each_entry_continue - continue iterating over hash chain | |
396 | * @tpos: the type * to use as a loop cursor. | |
397 | * @pos: the &struct rhash_head to use as a loop cursor. | |
398 | * @head: the previous &struct rhash_head to continue from | |
399 | * @tbl: the &struct bucket_table | |
400 | * @hash: the hash value / bucket index | |
401 | * @member: name of the &struct rhash_head within the hashable struct. | |
402 | */ | |
403 | #define rht_for_each_entry_continue(tpos, pos, head, tbl, hash, member) \ | |
404 | for (pos = rht_dereference_bucket(head, tbl, hash); \ | |
f89bd6f8 | 405 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \ |
88d6ed15 | 406 | pos = rht_dereference_bucket((pos)->next, tbl, hash)) |
7e1e7763 TG |
407 | |
408 | /** | |
409 | * rht_for_each_entry - iterate over hash chain of given type | |
88d6ed15 TG |
410 | * @tpos: the type * to use as a loop cursor. |
411 | * @pos: the &struct rhash_head to use as a loop cursor. | |
412 | * @tbl: the &struct bucket_table | |
413 | * @hash: the hash value / bucket index | |
414 | * @member: name of the &struct rhash_head within the hashable struct. | |
7e1e7763 | 415 | */ |
88d6ed15 TG |
416 | #define rht_for_each_entry(tpos, pos, tbl, hash, member) \ |
417 | rht_for_each_entry_continue(tpos, pos, (tbl)->buckets[hash], \ | |
418 | tbl, hash, member) | |
7e1e7763 TG |
419 | |
420 | /** | |
421 | * rht_for_each_entry_safe - safely iterate over hash chain of given type | |
88d6ed15 TG |
422 | * @tpos: the type * to use as a loop cursor. |
423 | * @pos: the &struct rhash_head to use as a loop cursor. | |
424 | * @next: the &struct rhash_head to use as next in loop cursor. | |
425 | * @tbl: the &struct bucket_table | |
426 | * @hash: the hash value / bucket index | |
427 | * @member: name of the &struct rhash_head within the hashable struct. | |
7e1e7763 TG |
428 | * |
429 | * This hash chain list-traversal primitive allows for the looped code to | |
430 | * remove the loop cursor from the list. | |
431 | */ | |
88d6ed15 TG |
432 | #define rht_for_each_entry_safe(tpos, pos, next, tbl, hash, member) \ |
433 | for (pos = rht_dereference_bucket((tbl)->buckets[hash], tbl, hash), \ | |
f89bd6f8 TG |
434 | next = !rht_is_a_nulls(pos) ? \ |
435 | rht_dereference_bucket(pos->next, tbl, hash) : NULL; \ | |
436 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \ | |
607954b0 PM |
437 | pos = next, \ |
438 | next = !rht_is_a_nulls(pos) ? \ | |
439 | rht_dereference_bucket(pos->next, tbl, hash) : NULL) | |
88d6ed15 TG |
440 | |
441 | /** | |
442 | * rht_for_each_rcu_continue - continue iterating over rcu hash chain | |
443 | * @pos: the &struct rhash_head to use as a loop cursor. | |
444 | * @head: the previous &struct rhash_head to continue from | |
445 | * @tbl: the &struct bucket_table | |
446 | * @hash: the hash value / bucket index | |
447 | * | |
448 | * This hash chain list-traversal primitive may safely run concurrently with | |
449 | * the _rcu mutation primitives such as rhashtable_insert() as long as the | |
450 | * traversal is guarded by rcu_read_lock(). | |
451 | */ | |
452 | #define rht_for_each_rcu_continue(pos, head, tbl, hash) \ | |
453 | for (({barrier(); }), \ | |
454 | pos = rht_dereference_bucket_rcu(head, tbl, hash); \ | |
f89bd6f8 | 455 | !rht_is_a_nulls(pos); \ |
88d6ed15 | 456 | pos = rcu_dereference_raw(pos->next)) |
7e1e7763 TG |
457 | |
458 | /** | |
459 | * rht_for_each_rcu - iterate over rcu hash chain | |
88d6ed15 TG |
460 | * @pos: the &struct rhash_head to use as a loop cursor. |
461 | * @tbl: the &struct bucket_table | |
462 | * @hash: the hash value / bucket index | |
7e1e7763 TG |
463 | * |
464 | * This hash chain list-traversal primitive may safely run concurrently with | |
88d6ed15 | 465 | * the _rcu mutation primitives such as rhashtable_insert() as long as the |
7e1e7763 TG |
466 | * traversal is guarded by rcu_read_lock(). |
467 | */ | |
88d6ed15 TG |
468 | #define rht_for_each_rcu(pos, tbl, hash) \ |
469 | rht_for_each_rcu_continue(pos, (tbl)->buckets[hash], tbl, hash) | |
470 | ||
471 | /** | |
472 | * rht_for_each_entry_rcu_continue - continue iterating over rcu hash chain | |
473 | * @tpos: the type * to use as a loop cursor. | |
474 | * @pos: the &struct rhash_head to use as a loop cursor. | |
475 | * @head: the previous &struct rhash_head to continue from | |
476 | * @tbl: the &struct bucket_table | |
477 | * @hash: the hash value / bucket index | |
478 | * @member: name of the &struct rhash_head within the hashable struct. | |
479 | * | |
480 | * This hash chain list-traversal primitive may safely run concurrently with | |
481 | * the _rcu mutation primitives such as rhashtable_insert() as long as the | |
482 | * traversal is guarded by rcu_read_lock(). | |
483 | */ | |
484 | #define rht_for_each_entry_rcu_continue(tpos, pos, head, tbl, hash, member) \ | |
485 | for (({barrier(); }), \ | |
486 | pos = rht_dereference_bucket_rcu(head, tbl, hash); \ | |
f89bd6f8 | 487 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \ |
88d6ed15 | 488 | pos = rht_dereference_bucket_rcu(pos->next, tbl, hash)) |
7e1e7763 TG |
489 | |
490 | /** | |
491 | * rht_for_each_entry_rcu - iterate over rcu hash chain of given type | |
88d6ed15 TG |
492 | * @tpos: the type * to use as a loop cursor. |
493 | * @pos: the &struct rhash_head to use as a loop cursor. | |
494 | * @tbl: the &struct bucket_table | |
495 | * @hash: the hash value / bucket index | |
496 | * @member: name of the &struct rhash_head within the hashable struct. | |
7e1e7763 TG |
497 | * |
498 | * This hash chain list-traversal primitive may safely run concurrently with | |
88d6ed15 | 499 | * the _rcu mutation primitives such as rhashtable_insert() as long as the |
7e1e7763 TG |
500 | * traversal is guarded by rcu_read_lock(). |
501 | */ | |
88d6ed15 TG |
502 | #define rht_for_each_entry_rcu(tpos, pos, tbl, hash, member) \ |
503 | rht_for_each_entry_rcu_continue(tpos, pos, (tbl)->buckets[hash],\ | |
504 | tbl, hash, member) | |
7e1e7763 | 505 | |
02fd97c3 HX |
506 | static inline int rhashtable_compare(struct rhashtable_compare_arg *arg, |
507 | const void *obj) | |
508 | { | |
509 | struct rhashtable *ht = arg->ht; | |
510 | const char *ptr = obj; | |
511 | ||
512 | return memcmp(ptr + ht->p.key_offset, arg->key, ht->p.key_len); | |
513 | } | |
514 | ||
515 | /** | |
516 | * rhashtable_lookup_fast - search hash table, inlined version | |
517 | * @ht: hash table | |
518 | * @key: the pointer to the key | |
519 | * @params: hash table parameters | |
520 | * | |
521 | * Computes the hash value for the key and traverses the bucket chain looking | |
522 | * for a entry with an identical key. The first matching entry is returned. | |
523 | * | |
524 | * Returns the first entry on which the compare function returned true. | |
525 | */ | |
526 | static inline void *rhashtable_lookup_fast( | |
527 | struct rhashtable *ht, const void *key, | |
528 | const struct rhashtable_params params) | |
529 | { | |
530 | struct rhashtable_compare_arg arg = { | |
531 | .ht = ht, | |
532 | .key = key, | |
533 | }; | |
534 | const struct bucket_table *tbl; | |
535 | struct rhash_head *he; | |
299e5c32 | 536 | unsigned int hash; |
02fd97c3 HX |
537 | |
538 | rcu_read_lock(); | |
539 | ||
540 | tbl = rht_dereference_rcu(ht->tbl, ht); | |
541 | restart: | |
542 | hash = rht_key_hashfn(ht, tbl, key, params); | |
543 | rht_for_each_rcu(he, tbl, hash) { | |
544 | if (params.obj_cmpfn ? | |
545 | params.obj_cmpfn(&arg, rht_obj(ht, he)) : | |
546 | rhashtable_compare(&arg, rht_obj(ht, he))) | |
547 | continue; | |
548 | rcu_read_unlock(); | |
549 | return rht_obj(ht, he); | |
550 | } | |
551 | ||
552 | /* Ensure we see any new tables. */ | |
553 | smp_rmb(); | |
554 | ||
555 | tbl = rht_dereference_rcu(tbl->future_tbl, ht); | |
556 | if (unlikely(tbl)) | |
557 | goto restart; | |
558 | rcu_read_unlock(); | |
559 | ||
560 | return NULL; | |
561 | } | |
562 | ||
ac833bdd | 563 | /* Internal function, please use rhashtable_insert_fast() instead */ |
02fd97c3 HX |
564 | static inline int __rhashtable_insert_fast( |
565 | struct rhashtable *ht, const void *key, struct rhash_head *obj, | |
566 | const struct rhashtable_params params) | |
567 | { | |
568 | struct rhashtable_compare_arg arg = { | |
569 | .ht = ht, | |
570 | .key = key, | |
571 | }; | |
02fd97c3 HX |
572 | struct bucket_table *tbl, *new_tbl; |
573 | struct rhash_head *head; | |
574 | spinlock_t *lock; | |
299e5c32 TG |
575 | unsigned int elasticity; |
576 | unsigned int hash; | |
ccd57b1b | 577 | int err; |
02fd97c3 | 578 | |
ccd57b1b | 579 | restart: |
02fd97c3 HX |
580 | rcu_read_lock(); |
581 | ||
582 | tbl = rht_dereference_rcu(ht->tbl, ht); | |
02fd97c3 | 583 | |
b824478b HX |
584 | /* All insertions must grab the oldest table containing |
585 | * the hashed bucket that is yet to be rehashed. | |
02fd97c3 | 586 | */ |
b824478b HX |
587 | for (;;) { |
588 | hash = rht_head_hashfn(ht, tbl, obj, params); | |
589 | lock = rht_bucket_lock(tbl, hash); | |
590 | spin_lock_bh(lock); | |
591 | ||
592 | if (tbl->rehash <= hash) | |
593 | break; | |
594 | ||
595 | spin_unlock_bh(lock); | |
596 | tbl = rht_dereference_rcu(tbl->future_tbl, ht); | |
597 | } | |
598 | ||
02fd97c3 HX |
599 | new_tbl = rht_dereference_rcu(tbl->future_tbl, ht); |
600 | if (unlikely(new_tbl)) { | |
601 | err = rhashtable_insert_slow(ht, key, obj, new_tbl); | |
ccd57b1b HX |
602 | if (err == -EAGAIN) |
603 | goto slow_path; | |
02fd97c3 HX |
604 | goto out; |
605 | } | |
606 | ||
07ee0722 HX |
607 | err = -E2BIG; |
608 | if (unlikely(rht_grow_above_max(ht, tbl))) | |
609 | goto out; | |
610 | ||
ccd57b1b HX |
611 | if (unlikely(rht_grow_above_100(ht, tbl))) { |
612 | slow_path: | |
613 | spin_unlock_bh(lock); | |
ccd57b1b | 614 | err = rhashtable_insert_rehash(ht); |
58be8a58 | 615 | rcu_read_unlock(); |
ccd57b1b HX |
616 | if (err) |
617 | return err; | |
618 | ||
619 | goto restart; | |
620 | } | |
02fd97c3 | 621 | |
ccd57b1b HX |
622 | err = -EEXIST; |
623 | elasticity = ht->elasticity; | |
02fd97c3 | 624 | rht_for_each(head, tbl, hash) { |
ccd57b1b HX |
625 | if (key && |
626 | unlikely(!(params.obj_cmpfn ? | |
02fd97c3 HX |
627 | params.obj_cmpfn(&arg, rht_obj(ht, head)) : |
628 | rhashtable_compare(&arg, rht_obj(ht, head))))) | |
629 | goto out; | |
ccd57b1b HX |
630 | if (!--elasticity) |
631 | goto slow_path; | |
02fd97c3 HX |
632 | } |
633 | ||
02fd97c3 HX |
634 | err = 0; |
635 | ||
636 | head = rht_dereference_bucket(tbl->buckets[hash], tbl, hash); | |
637 | ||
638 | RCU_INIT_POINTER(obj->next, head); | |
639 | ||
640 | rcu_assign_pointer(tbl->buckets[hash], obj); | |
641 | ||
642 | atomic_inc(&ht->nelems); | |
643 | if (rht_grow_above_75(ht, tbl)) | |
644 | schedule_work(&ht->run_work); | |
645 | ||
646 | out: | |
647 | spin_unlock_bh(lock); | |
648 | rcu_read_unlock(); | |
649 | ||
650 | return err; | |
651 | } | |
652 | ||
653 | /** | |
654 | * rhashtable_insert_fast - insert object into hash table | |
655 | * @ht: hash table | |
656 | * @obj: pointer to hash head inside object | |
657 | * @params: hash table parameters | |
658 | * | |
659 | * Will take a per bucket spinlock to protect against mutual mutations | |
660 | * on the same bucket. Multiple insertions may occur in parallel unless | |
661 | * they map to the same bucket lock. | |
662 | * | |
663 | * It is safe to call this function from atomic context. | |
664 | * | |
665 | * Will trigger an automatic deferred table resizing if the size grows | |
666 | * beyond the watermark indicated by grow_decision() which can be passed | |
667 | * to rhashtable_init(). | |
668 | */ | |
669 | static inline int rhashtable_insert_fast( | |
670 | struct rhashtable *ht, struct rhash_head *obj, | |
671 | const struct rhashtable_params params) | |
672 | { | |
673 | return __rhashtable_insert_fast(ht, NULL, obj, params); | |
674 | } | |
675 | ||
676 | /** | |
677 | * rhashtable_lookup_insert_fast - lookup and insert object into hash table | |
678 | * @ht: hash table | |
679 | * @obj: pointer to hash head inside object | |
680 | * @params: hash table parameters | |
681 | * | |
682 | * Locks down the bucket chain in both the old and new table if a resize | |
683 | * is in progress to ensure that writers can't remove from the old table | |
684 | * and can't insert to the new table during the atomic operation of search | |
685 | * and insertion. Searches for duplicates in both the old and new table if | |
686 | * a resize is in progress. | |
687 | * | |
688 | * This lookup function may only be used for fixed key hash table (key_len | |
689 | * parameter set). It will BUG() if used inappropriately. | |
690 | * | |
691 | * It is safe to call this function from atomic context. | |
692 | * | |
693 | * Will trigger an automatic deferred table resizing if the size grows | |
694 | * beyond the watermark indicated by grow_decision() which can be passed | |
695 | * to rhashtable_init(). | |
696 | */ | |
697 | static inline int rhashtable_lookup_insert_fast( | |
698 | struct rhashtable *ht, struct rhash_head *obj, | |
699 | const struct rhashtable_params params) | |
700 | { | |
701 | const char *key = rht_obj(ht, obj); | |
702 | ||
703 | BUG_ON(ht->p.obj_hashfn); | |
704 | ||
705 | return __rhashtable_insert_fast(ht, key + ht->p.key_offset, obj, | |
706 | params); | |
707 | } | |
708 | ||
709 | /** | |
710 | * rhashtable_lookup_insert_key - search and insert object to hash table | |
711 | * with explicit key | |
712 | * @ht: hash table | |
713 | * @key: key | |
714 | * @obj: pointer to hash head inside object | |
715 | * @params: hash table parameters | |
716 | * | |
717 | * Locks down the bucket chain in both the old and new table if a resize | |
718 | * is in progress to ensure that writers can't remove from the old table | |
719 | * and can't insert to the new table during the atomic operation of search | |
720 | * and insertion. Searches for duplicates in both the old and new table if | |
721 | * a resize is in progress. | |
722 | * | |
723 | * Lookups may occur in parallel with hashtable mutations and resizing. | |
724 | * | |
725 | * Will trigger an automatic deferred table resizing if the size grows | |
726 | * beyond the watermark indicated by grow_decision() which can be passed | |
727 | * to rhashtable_init(). | |
728 | * | |
729 | * Returns zero on success. | |
730 | */ | |
731 | static inline int rhashtable_lookup_insert_key( | |
732 | struct rhashtable *ht, const void *key, struct rhash_head *obj, | |
733 | const struct rhashtable_params params) | |
734 | { | |
735 | BUG_ON(!ht->p.obj_hashfn || !key); | |
736 | ||
737 | return __rhashtable_insert_fast(ht, key, obj, params); | |
738 | } | |
739 | ||
ac833bdd | 740 | /* Internal function, please use rhashtable_remove_fast() instead */ |
02fd97c3 HX |
741 | static inline int __rhashtable_remove_fast( |
742 | struct rhashtable *ht, struct bucket_table *tbl, | |
743 | struct rhash_head *obj, const struct rhashtable_params params) | |
744 | { | |
745 | struct rhash_head __rcu **pprev; | |
746 | struct rhash_head *he; | |
747 | spinlock_t * lock; | |
299e5c32 | 748 | unsigned int hash; |
02fd97c3 HX |
749 | int err = -ENOENT; |
750 | ||
751 | hash = rht_head_hashfn(ht, tbl, obj, params); | |
752 | lock = rht_bucket_lock(tbl, hash); | |
753 | ||
754 | spin_lock_bh(lock); | |
755 | ||
756 | pprev = &tbl->buckets[hash]; | |
757 | rht_for_each(he, tbl, hash) { | |
758 | if (he != obj) { | |
759 | pprev = &he->next; | |
760 | continue; | |
761 | } | |
762 | ||
763 | rcu_assign_pointer(*pprev, obj->next); | |
764 | err = 0; | |
765 | break; | |
766 | } | |
767 | ||
768 | spin_unlock_bh(lock); | |
769 | ||
770 | return err; | |
771 | } | |
772 | ||
773 | /** | |
774 | * rhashtable_remove_fast - remove object from hash table | |
775 | * @ht: hash table | |
776 | * @obj: pointer to hash head inside object | |
777 | * @params: hash table parameters | |
778 | * | |
779 | * Since the hash chain is single linked, the removal operation needs to | |
780 | * walk the bucket chain upon removal. The removal operation is thus | |
781 | * considerable slow if the hash table is not correctly sized. | |
782 | * | |
783 | * Will automatically shrink the table via rhashtable_expand() if the | |
784 | * shrink_decision function specified at rhashtable_init() returns true. | |
785 | * | |
786 | * Returns zero on success, -ENOENT if the entry could not be found. | |
787 | */ | |
788 | static inline int rhashtable_remove_fast( | |
789 | struct rhashtable *ht, struct rhash_head *obj, | |
790 | const struct rhashtable_params params) | |
791 | { | |
792 | struct bucket_table *tbl; | |
793 | int err; | |
794 | ||
795 | rcu_read_lock(); | |
796 | ||
797 | tbl = rht_dereference_rcu(ht->tbl, ht); | |
798 | ||
799 | /* Because we have already taken (and released) the bucket | |
800 | * lock in old_tbl, if we find that future_tbl is not yet | |
801 | * visible then that guarantees the entry to still be in | |
802 | * the old tbl if it exists. | |
803 | */ | |
804 | while ((err = __rhashtable_remove_fast(ht, tbl, obj, params)) && | |
805 | (tbl = rht_dereference_rcu(tbl->future_tbl, ht))) | |
806 | ; | |
807 | ||
808 | if (err) | |
809 | goto out; | |
810 | ||
811 | atomic_dec(&ht->nelems); | |
b5e2c150 TG |
812 | if (unlikely(ht->p.automatic_shrinking && |
813 | rht_shrink_below_30(ht, tbl))) | |
02fd97c3 HX |
814 | schedule_work(&ht->run_work); |
815 | ||
816 | out: | |
817 | rcu_read_unlock(); | |
818 | ||
819 | return err; | |
820 | } | |
821 | ||
7e1e7763 | 822 | #endif /* _LINUX_RHASHTABLE_H */ |