Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 1 | /* |
| 2 | * Resizable, Scalable, Concurrent Hash Table |
| 3 | * |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 4 | * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au> |
Thomas Graf | a5ec68e | 2015-02-05 02:03:32 +0100 | [diff] [blame] | 5 | * Copyright (c) 2014-2015 Thomas Graf <tgraf@suug.ch> |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 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 | 02fd97c | 2015-03-20 21:57:00 +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 | |
Herbert Xu | 07ee072 | 2015-05-15 11:30:47 +0800 | [diff] [blame] | 17 | #include <linux/atomic.h> |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 18 | #include <linux/kernel.h> |
| 19 | #include <linux/init.h> |
| 20 | #include <linux/log2.h> |
Eric Dumazet | 5beb5c9 | 2015-02-26 07:20:34 -0800 | [diff] [blame] | 21 | #include <linux/sched.h> |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 22 | #include <linux/slab.h> |
| 23 | #include <linux/vmalloc.h> |
| 24 | #include <linux/mm.h> |
Daniel Borkmann | 8754589 | 2014-12-10 16:33:11 +0100 | [diff] [blame] | 25 | #include <linux/jhash.h> |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 26 | #include <linux/random.h> |
| 27 | #include <linux/rhashtable.h> |
Stephen Rothwell | 61d7b09 | 2015-02-09 14:04:03 +1100 | [diff] [blame] | 28 | #include <linux/err.h> |
Hauke Mehrtens | 6d79541 | 2015-06-06 22:07:23 +0200 | [diff] [blame] | 29 | #include <linux/export.h> |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 30 | |
| 31 | #define HASH_DEFAULT_SIZE 64UL |
Herbert Xu | c2e213c | 2015-03-18 20:01:16 +1100 | [diff] [blame] | 32 | #define HASH_MIN_SIZE 4U |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 33 | #define BUCKET_LOCKS_PER_CPU 128UL |
| 34 | |
Herbert Xu | 988dfbd | 2015-03-10 09:27:55 +1100 | [diff] [blame] | 35 | static u32 head_hashfn(struct rhashtable *ht, |
Thomas Graf | 8d24c0b | 2015-01-02 23:00:14 +0100 | [diff] [blame] | 36 | const struct bucket_table *tbl, |
| 37 | const struct rhash_head *he) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 38 | { |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 39 | return rht_head_hashfn(ht, tbl, he, ht->p); |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 40 | } |
| 41 | |
Thomas Graf | a03eaec | 2015-02-05 02:03:34 +0100 | [diff] [blame] | 42 | #ifdef CONFIG_PROVE_LOCKING |
Thomas Graf | a03eaec | 2015-02-05 02:03:34 +0100 | [diff] [blame] | 43 | #define ASSERT_RHT_MUTEX(HT) BUG_ON(!lockdep_rht_mutex_is_held(HT)) |
Thomas Graf | a03eaec | 2015-02-05 02:03:34 +0100 | [diff] [blame] | 44 | |
| 45 | int lockdep_rht_mutex_is_held(struct rhashtable *ht) |
| 46 | { |
| 47 | return (debug_locks) ? lockdep_is_held(&ht->mutex) : 1; |
| 48 | } |
| 49 | EXPORT_SYMBOL_GPL(lockdep_rht_mutex_is_held); |
| 50 | |
| 51 | int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash) |
| 52 | { |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 53 | spinlock_t *lock = rht_bucket_lock(tbl, hash); |
Thomas Graf | a03eaec | 2015-02-05 02:03:34 +0100 | [diff] [blame] | 54 | |
| 55 | return (debug_locks) ? lockdep_is_held(lock) : 1; |
| 56 | } |
| 57 | EXPORT_SYMBOL_GPL(lockdep_rht_bucket_is_held); |
| 58 | #else |
| 59 | #define ASSERT_RHT_MUTEX(HT) |
Thomas Graf | a03eaec | 2015-02-05 02:03:34 +0100 | [diff] [blame] | 60 | #endif |
| 61 | |
| 62 | |
Herbert Xu | b9ecfda | 2015-03-24 00:50:27 +1100 | [diff] [blame] | 63 | static int alloc_bucket_locks(struct rhashtable *ht, struct bucket_table *tbl, |
| 64 | gfp_t gfp) |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 65 | { |
| 66 | unsigned int i, size; |
| 67 | #if defined(CONFIG_PROVE_LOCKING) |
| 68 | unsigned int nr_pcpus = 2; |
| 69 | #else |
| 70 | unsigned int nr_pcpus = num_possible_cpus(); |
| 71 | #endif |
| 72 | |
| 73 | nr_pcpus = min_t(unsigned int, nr_pcpus, 32UL); |
| 74 | size = roundup_pow_of_two(nr_pcpus * ht->p.locks_mul); |
| 75 | |
Thomas Graf | a5ec68e | 2015-02-05 02:03:32 +0100 | [diff] [blame] | 76 | /* Never allocate more than 0.5 locks per bucket */ |
| 77 | size = min_t(unsigned int, size, tbl->size >> 1); |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 78 | |
| 79 | if (sizeof(spinlock_t) != 0) { |
| 80 | #ifdef CONFIG_NUMA |
Herbert Xu | b9ecfda | 2015-03-24 00:50:27 +1100 | [diff] [blame] | 81 | if (size * sizeof(spinlock_t) > PAGE_SIZE && |
| 82 | gfp == GFP_KERNEL) |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 83 | tbl->locks = vmalloc(size * sizeof(spinlock_t)); |
| 84 | else |
| 85 | #endif |
| 86 | tbl->locks = kmalloc_array(size, sizeof(spinlock_t), |
Herbert Xu | b9ecfda | 2015-03-24 00:50:27 +1100 | [diff] [blame] | 87 | gfp); |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 88 | if (!tbl->locks) |
| 89 | return -ENOMEM; |
| 90 | for (i = 0; i < size; i++) |
| 91 | spin_lock_init(&tbl->locks[i]); |
| 92 | } |
| 93 | tbl->locks_mask = size - 1; |
| 94 | |
| 95 | return 0; |
| 96 | } |
| 97 | |
| 98 | static void bucket_table_free(const struct bucket_table *tbl) |
| 99 | { |
| 100 | if (tbl) |
| 101 | kvfree(tbl->locks); |
| 102 | |
| 103 | kvfree(tbl); |
| 104 | } |
| 105 | |
Herbert Xu | 9d901bc | 2015-03-14 13:57:23 +1100 | [diff] [blame] | 106 | static void bucket_table_free_rcu(struct rcu_head *head) |
| 107 | { |
| 108 | bucket_table_free(container_of(head, struct bucket_table, rcu)); |
| 109 | } |
| 110 | |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 111 | static struct bucket_table *bucket_table_alloc(struct rhashtable *ht, |
Herbert Xu | b9ecfda | 2015-03-24 00:50:27 +1100 | [diff] [blame] | 112 | size_t nbuckets, |
| 113 | gfp_t gfp) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 114 | { |
Daniel Borkmann | eb6d1ab | 2015-02-20 00:53:38 +0100 | [diff] [blame] | 115 | struct bucket_table *tbl = NULL; |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 116 | size_t size; |
Thomas Graf | f89bd6f | 2015-01-02 23:00:21 +0100 | [diff] [blame] | 117 | int i; |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 118 | |
| 119 | size = sizeof(*tbl) + nbuckets * sizeof(tbl->buckets[0]); |
Herbert Xu | b9ecfda | 2015-03-24 00:50:27 +1100 | [diff] [blame] | 120 | if (size <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER) || |
| 121 | gfp != GFP_KERNEL) |
| 122 | tbl = kzalloc(size, gfp | __GFP_NOWARN | __GFP_NORETRY); |
| 123 | if (tbl == NULL && gfp == GFP_KERNEL) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 124 | tbl = vzalloc(size); |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 125 | if (tbl == NULL) |
| 126 | return NULL; |
| 127 | |
| 128 | tbl->size = nbuckets; |
| 129 | |
Herbert Xu | b9ecfda | 2015-03-24 00:50:27 +1100 | [diff] [blame] | 130 | if (alloc_bucket_locks(ht, tbl, gfp) < 0) { |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 131 | bucket_table_free(tbl); |
| 132 | return NULL; |
| 133 | } |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 134 | |
Herbert Xu | eddee5ba | 2015-03-14 13:57:20 +1100 | [diff] [blame] | 135 | INIT_LIST_HEAD(&tbl->walkers); |
| 136 | |
Herbert Xu | 5269b53 | 2015-03-14 13:57:22 +1100 | [diff] [blame] | 137 | get_random_bytes(&tbl->hash_rnd, sizeof(tbl->hash_rnd)); |
| 138 | |
Thomas Graf | f89bd6f | 2015-01-02 23:00:21 +0100 | [diff] [blame] | 139 | for (i = 0; i < nbuckets; i++) |
| 140 | INIT_RHT_NULLS_HEAD(tbl->buckets[i], ht, i); |
| 141 | |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 142 | return tbl; |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 143 | } |
| 144 | |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 145 | static struct bucket_table *rhashtable_last_table(struct rhashtable *ht, |
| 146 | struct bucket_table *tbl) |
| 147 | { |
| 148 | struct bucket_table *new_tbl; |
| 149 | |
| 150 | do { |
| 151 | new_tbl = tbl; |
| 152 | tbl = rht_dereference_rcu(tbl->future_tbl, ht); |
| 153 | } while (tbl); |
| 154 | |
| 155 | return new_tbl; |
| 156 | } |
| 157 | |
Thomas Graf | 299e5c3 | 2015-03-24 14:18:17 +0100 | [diff] [blame] | 158 | static int rhashtable_rehash_one(struct rhashtable *ht, unsigned int old_hash) |
Thomas Graf | a5ec68e | 2015-02-05 02:03:32 +0100 | [diff] [blame] | 159 | { |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 160 | struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht); |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 161 | struct bucket_table *new_tbl = rhashtable_last_table(ht, |
| 162 | rht_dereference_rcu(old_tbl->future_tbl, ht)); |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 163 | struct rhash_head __rcu **pprev = &old_tbl->buckets[old_hash]; |
| 164 | int err = -ENOENT; |
| 165 | struct rhash_head *head, *next, *entry; |
| 166 | spinlock_t *new_bucket_lock; |
Thomas Graf | 299e5c3 | 2015-03-24 14:18:17 +0100 | [diff] [blame] | 167 | unsigned int new_hash; |
Thomas Graf | a5ec68e | 2015-02-05 02:03:32 +0100 | [diff] [blame] | 168 | |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 169 | rht_for_each(entry, old_tbl, old_hash) { |
| 170 | err = 0; |
| 171 | next = rht_dereference_bucket(entry->next, old_tbl, old_hash); |
Thomas Graf | a5ec68e | 2015-02-05 02:03:32 +0100 | [diff] [blame] | 172 | |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 173 | if (rht_is_a_nulls(next)) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 174 | break; |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 175 | |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 176 | pprev = &entry->next; |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 177 | } |
| 178 | |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 179 | if (err) |
| 180 | goto out; |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 181 | |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 182 | new_hash = head_hashfn(ht, new_tbl, entry); |
Thomas Graf | a5ec68e | 2015-02-05 02:03:32 +0100 | [diff] [blame] | 183 | |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 184 | new_bucket_lock = rht_bucket_lock(new_tbl, new_hash); |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 185 | |
Herbert Xu | 8f2484b | 2015-03-14 13:57:21 +1100 | [diff] [blame] | 186 | spin_lock_nested(new_bucket_lock, SINGLE_DEPTH_NESTING); |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 187 | head = rht_dereference_bucket(new_tbl->buckets[new_hash], |
| 188 | new_tbl, new_hash); |
| 189 | |
| 190 | if (rht_is_a_nulls(head)) |
| 191 | INIT_RHT_NULLS_HEAD(entry->next, ht, new_hash); |
| 192 | else |
| 193 | RCU_INIT_POINTER(entry->next, head); |
| 194 | |
| 195 | rcu_assign_pointer(new_tbl->buckets[new_hash], entry); |
| 196 | spin_unlock(new_bucket_lock); |
| 197 | |
| 198 | rcu_assign_pointer(*pprev, next); |
| 199 | |
| 200 | out: |
| 201 | return err; |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 202 | } |
| 203 | |
Thomas Graf | 299e5c3 | 2015-03-24 14:18:17 +0100 | [diff] [blame] | 204 | static void rhashtable_rehash_chain(struct rhashtable *ht, |
| 205 | unsigned int old_hash) |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 206 | { |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 207 | struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht); |
| 208 | spinlock_t *old_bucket_lock; |
Thomas Graf | 7cd10db | 2015-02-05 02:03:35 +0100 | [diff] [blame] | 209 | |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 210 | old_bucket_lock = rht_bucket_lock(old_tbl, old_hash); |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 211 | |
| 212 | spin_lock_bh(old_bucket_lock); |
| 213 | while (!rhashtable_rehash_one(ht, old_hash)) |
| 214 | ; |
Herbert Xu | 63d512d | 2015-03-14 13:57:24 +1100 | [diff] [blame] | 215 | old_tbl->rehash++; |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 216 | spin_unlock_bh(old_bucket_lock); |
| 217 | } |
| 218 | |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 219 | static int rhashtable_rehash_attach(struct rhashtable *ht, |
| 220 | struct bucket_table *old_tbl, |
| 221 | struct bucket_table *new_tbl) |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 222 | { |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 223 | /* Protect future_tbl using the first bucket lock. */ |
| 224 | spin_lock_bh(old_tbl->locks); |
| 225 | |
| 226 | /* Did somebody beat us to it? */ |
| 227 | if (rcu_access_pointer(old_tbl->future_tbl)) { |
| 228 | spin_unlock_bh(old_tbl->locks); |
| 229 | return -EEXIST; |
| 230 | } |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 231 | |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 232 | /* Make insertions go into the new, empty table right away. Deletions |
| 233 | * and lookups will be attempted in both tables until we synchronize. |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 234 | */ |
Herbert Xu | c4db884 | 2015-03-14 13:57:25 +1100 | [diff] [blame] | 235 | rcu_assign_pointer(old_tbl->future_tbl, new_tbl); |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 236 | |
Herbert Xu | 9497df8 | 2015-03-12 22:07:49 +1100 | [diff] [blame] | 237 | /* Ensure the new table is visible to readers. */ |
| 238 | smp_wmb(); |
| 239 | |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 240 | spin_unlock_bh(old_tbl->locks); |
| 241 | |
| 242 | return 0; |
| 243 | } |
| 244 | |
| 245 | static int rhashtable_rehash_table(struct rhashtable *ht) |
| 246 | { |
| 247 | struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht); |
| 248 | struct bucket_table *new_tbl; |
| 249 | struct rhashtable_walker *walker; |
Thomas Graf | 299e5c3 | 2015-03-24 14:18:17 +0100 | [diff] [blame] | 250 | unsigned int old_hash; |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 251 | |
| 252 | new_tbl = rht_dereference(old_tbl->future_tbl, ht); |
| 253 | if (!new_tbl) |
| 254 | return 0; |
| 255 | |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 256 | for (old_hash = 0; old_hash < old_tbl->size; old_hash++) |
| 257 | rhashtable_rehash_chain(ht, old_hash); |
| 258 | |
| 259 | /* Publish the new table pointer. */ |
| 260 | rcu_assign_pointer(ht->tbl, new_tbl); |
| 261 | |
Herbert Xu | ba7c95e | 2015-03-24 09:53:17 +1100 | [diff] [blame] | 262 | spin_lock(&ht->lock); |
Herbert Xu | eddee5ba | 2015-03-14 13:57:20 +1100 | [diff] [blame] | 263 | list_for_each_entry(walker, &old_tbl->walkers, list) |
| 264 | walker->tbl = NULL; |
Herbert Xu | ba7c95e | 2015-03-24 09:53:17 +1100 | [diff] [blame] | 265 | spin_unlock(&ht->lock); |
Herbert Xu | eddee5ba | 2015-03-14 13:57:20 +1100 | [diff] [blame] | 266 | |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 267 | /* Wait for readers. All new readers will see the new |
| 268 | * table, and thus no references to the old table will |
| 269 | * remain. |
| 270 | */ |
Herbert Xu | 9d901bc | 2015-03-14 13:57:23 +1100 | [diff] [blame] | 271 | call_rcu(&old_tbl->rcu, bucket_table_free_rcu); |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 272 | |
| 273 | return rht_dereference(new_tbl->future_tbl, ht) ? -EAGAIN : 0; |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 274 | } |
| 275 | |
| 276 | /** |
| 277 | * rhashtable_expand - Expand hash table while allowing concurrent lookups |
| 278 | * @ht: the hash table to expand |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 279 | * |
Herbert Xu | aa34a6cb0 | 2015-03-11 09:43:48 +1100 | [diff] [blame] | 280 | * A secondary bucket array is allocated and the hash entries are migrated. |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 281 | * |
| 282 | * This function may only be called in a context where it is safe to call |
| 283 | * synchronize_rcu(), e.g. not within a rcu_read_lock() section. |
| 284 | * |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 285 | * The caller must ensure that no concurrent resizing occurs by holding |
| 286 | * ht->mutex. |
| 287 | * |
| 288 | * It is valid to have concurrent insertions and deletions protected by per |
| 289 | * bucket locks or concurrent RCU protected lookups and traversals. |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 290 | */ |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 291 | static int rhashtable_expand(struct rhashtable *ht) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 292 | { |
| 293 | struct bucket_table *new_tbl, *old_tbl = rht_dereference(ht->tbl, ht); |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 294 | int err; |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 295 | |
| 296 | ASSERT_RHT_MUTEX(ht); |
| 297 | |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 298 | old_tbl = rhashtable_last_table(ht, old_tbl); |
| 299 | |
Herbert Xu | b9ecfda | 2015-03-24 00:50:27 +1100 | [diff] [blame] | 300 | new_tbl = bucket_table_alloc(ht, old_tbl->size * 2, GFP_KERNEL); |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 301 | if (new_tbl == NULL) |
| 302 | return -ENOMEM; |
| 303 | |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 304 | err = rhashtable_rehash_attach(ht, old_tbl, new_tbl); |
| 305 | if (err) |
| 306 | bucket_table_free(new_tbl); |
| 307 | |
| 308 | return err; |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 309 | } |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 310 | |
| 311 | /** |
| 312 | * rhashtable_shrink - Shrink hash table while allowing concurrent lookups |
| 313 | * @ht: the hash table to shrink |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 314 | * |
Herbert Xu | 18093d1 | 2015-03-24 00:50:25 +1100 | [diff] [blame] | 315 | * This function shrinks the hash table to fit, i.e., the smallest |
| 316 | * size would not cause it to expand right away automatically. |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 317 | * |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 318 | * The caller must ensure that no concurrent resizing occurs by holding |
| 319 | * ht->mutex. |
| 320 | * |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 321 | * The caller must ensure that no concurrent table mutations take place. |
| 322 | * It is however valid to have concurrent lookups if they are RCU protected. |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 323 | * |
| 324 | * It is valid to have concurrent insertions and deletions protected by per |
| 325 | * bucket locks or concurrent RCU protected lookups and traversals. |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 326 | */ |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 327 | static int rhashtable_shrink(struct rhashtable *ht) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 328 | { |
Daniel Borkmann | a5b6846 | 2015-03-12 15:28:40 +0100 | [diff] [blame] | 329 | struct bucket_table *new_tbl, *old_tbl = rht_dereference(ht->tbl, ht); |
Thomas Graf | 299e5c3 | 2015-03-24 14:18:17 +0100 | [diff] [blame] | 330 | unsigned int size; |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 331 | int err; |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 332 | |
| 333 | ASSERT_RHT_MUTEX(ht); |
| 334 | |
Thomas Graf | 299e5c3 | 2015-03-24 14:18:17 +0100 | [diff] [blame] | 335 | size = roundup_pow_of_two(atomic_read(&ht->nelems) * 3 / 2); |
Herbert Xu | 18093d1 | 2015-03-24 00:50:25 +1100 | [diff] [blame] | 336 | if (size < ht->p.min_size) |
| 337 | size = ht->p.min_size; |
| 338 | |
| 339 | if (old_tbl->size <= size) |
| 340 | return 0; |
| 341 | |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 342 | if (rht_dereference(old_tbl->future_tbl, ht)) |
| 343 | return -EEXIST; |
| 344 | |
Herbert Xu | b9ecfda | 2015-03-24 00:50:27 +1100 | [diff] [blame] | 345 | new_tbl = bucket_table_alloc(ht, size, GFP_KERNEL); |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 346 | if (new_tbl == NULL) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 347 | return -ENOMEM; |
| 348 | |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 349 | err = rhashtable_rehash_attach(ht, old_tbl, new_tbl); |
| 350 | if (err) |
| 351 | bucket_table_free(new_tbl); |
| 352 | |
| 353 | return err; |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 354 | } |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 355 | |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 356 | static void rht_deferred_worker(struct work_struct *work) |
| 357 | { |
| 358 | struct rhashtable *ht; |
| 359 | struct bucket_table *tbl; |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 360 | int err = 0; |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 361 | |
Ying Xue | 57699a4 | 2015-01-16 11:13:09 +0800 | [diff] [blame] | 362 | ht = container_of(work, struct rhashtable, run_work); |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 363 | mutex_lock(&ht->mutex); |
Herbert Xu | 28134a5 | 2015-02-04 07:33:22 +1100 | [diff] [blame] | 364 | |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 365 | tbl = rht_dereference(ht->tbl, ht); |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 366 | tbl = rhashtable_last_table(ht, tbl); |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 367 | |
Daniel Borkmann | a5b6846 | 2015-03-12 15:28:40 +0100 | [diff] [blame] | 368 | if (rht_grow_above_75(ht, tbl)) |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 369 | rhashtable_expand(ht); |
Thomas Graf | b5e2c15 | 2015-03-24 20:42:19 +0000 | [diff] [blame] | 370 | else if (ht->p.automatic_shrinking && rht_shrink_below_30(ht, tbl)) |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 371 | rhashtable_shrink(ht); |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 372 | |
| 373 | err = rhashtable_rehash_table(ht); |
| 374 | |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 375 | mutex_unlock(&ht->mutex); |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 376 | |
| 377 | if (err) |
| 378 | schedule_work(&ht->run_work); |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 379 | } |
| 380 | |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 381 | static bool rhashtable_check_elasticity(struct rhashtable *ht, |
| 382 | struct bucket_table *tbl, |
Thomas Graf | 299e5c3 | 2015-03-24 14:18:17 +0100 | [diff] [blame] | 383 | unsigned int hash) |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 384 | { |
Thomas Graf | 299e5c3 | 2015-03-24 14:18:17 +0100 | [diff] [blame] | 385 | unsigned int elasticity = ht->elasticity; |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 386 | struct rhash_head *head; |
| 387 | |
| 388 | rht_for_each(head, tbl, hash) |
| 389 | if (!--elasticity) |
| 390 | return true; |
| 391 | |
| 392 | return false; |
| 393 | } |
| 394 | |
| 395 | int rhashtable_insert_rehash(struct rhashtable *ht) |
| 396 | { |
| 397 | struct bucket_table *old_tbl; |
| 398 | struct bucket_table *new_tbl; |
| 399 | struct bucket_table *tbl; |
| 400 | unsigned int size; |
| 401 | int err; |
| 402 | |
| 403 | old_tbl = rht_dereference_rcu(ht->tbl, ht); |
| 404 | tbl = rhashtable_last_table(ht, old_tbl); |
| 405 | |
| 406 | size = tbl->size; |
| 407 | |
| 408 | if (rht_grow_above_75(ht, tbl)) |
| 409 | size *= 2; |
Thomas Graf | a87b9eb | 2015-04-22 09:41:46 +0200 | [diff] [blame] | 410 | /* Do not schedule more than one rehash */ |
| 411 | else if (old_tbl != tbl) |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 412 | return -EBUSY; |
| 413 | |
| 414 | new_tbl = bucket_table_alloc(ht, size, GFP_ATOMIC); |
Thomas Graf | e2307ed | 2015-04-22 09:41:45 +0200 | [diff] [blame] | 415 | if (new_tbl == NULL) { |
| 416 | /* Schedule async resize/rehash to try allocation |
| 417 | * non-atomic context. |
| 418 | */ |
| 419 | schedule_work(&ht->run_work); |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 420 | return -ENOMEM; |
Thomas Graf | e2307ed | 2015-04-22 09:41:45 +0200 | [diff] [blame] | 421 | } |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 422 | |
| 423 | err = rhashtable_rehash_attach(ht, tbl, new_tbl); |
| 424 | if (err) { |
| 425 | bucket_table_free(new_tbl); |
| 426 | if (err == -EEXIST) |
| 427 | err = 0; |
| 428 | } else |
| 429 | schedule_work(&ht->run_work); |
| 430 | |
| 431 | return err; |
| 432 | } |
| 433 | EXPORT_SYMBOL_GPL(rhashtable_insert_rehash); |
| 434 | |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 435 | int rhashtable_insert_slow(struct rhashtable *ht, const void *key, |
| 436 | struct rhash_head *obj, |
| 437 | struct bucket_table *tbl) |
| 438 | { |
| 439 | struct rhash_head *head; |
Thomas Graf | 299e5c3 | 2015-03-24 14:18:17 +0100 | [diff] [blame] | 440 | unsigned int hash; |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 441 | int err; |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 442 | |
Herbert Xu | b824478 | 2015-03-24 00:50:26 +1100 | [diff] [blame] | 443 | tbl = rhashtable_last_table(ht, tbl); |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 444 | hash = head_hashfn(ht, tbl, obj); |
| 445 | spin_lock_nested(rht_bucket_lock(tbl, hash), SINGLE_DEPTH_NESTING); |
| 446 | |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 447 | err = -EEXIST; |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 448 | if (key && rhashtable_lookup_fast(ht, key, ht->p)) |
| 449 | goto exit; |
| 450 | |
Herbert Xu | 07ee072 | 2015-05-15 11:30:47 +0800 | [diff] [blame] | 451 | err = -E2BIG; |
| 452 | if (unlikely(rht_grow_above_max(ht, tbl))) |
| 453 | goto exit; |
| 454 | |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 455 | err = -EAGAIN; |
| 456 | if (rhashtable_check_elasticity(ht, tbl, hash) || |
| 457 | rht_grow_above_100(ht, tbl)) |
| 458 | goto exit; |
| 459 | |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 460 | err = 0; |
| 461 | |
| 462 | head = rht_dereference_bucket(tbl->buckets[hash], tbl, hash); |
| 463 | |
| 464 | RCU_INIT_POINTER(obj->next, head); |
| 465 | |
| 466 | rcu_assign_pointer(tbl->buckets[hash], obj); |
| 467 | |
| 468 | atomic_inc(&ht->nelems); |
| 469 | |
| 470 | exit: |
| 471 | spin_unlock(rht_bucket_lock(tbl, hash)); |
| 472 | |
| 473 | return err; |
| 474 | } |
| 475 | EXPORT_SYMBOL_GPL(rhashtable_insert_slow); |
| 476 | |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 477 | /** |
| 478 | * rhashtable_walk_init - Initialise an iterator |
| 479 | * @ht: Table to walk over |
| 480 | * @iter: Hash table Iterator |
| 481 | * |
| 482 | * This function prepares a hash table walk. |
| 483 | * |
| 484 | * Note that if you restart a walk after rhashtable_walk_stop you |
| 485 | * may see the same object twice. Also, you may miss objects if |
| 486 | * there are removals in between rhashtable_walk_stop and the next |
| 487 | * call to rhashtable_walk_start. |
| 488 | * |
| 489 | * For a completely stable walk you should construct your own data |
| 490 | * structure outside the hash table. |
| 491 | * |
| 492 | * This function may sleep so you must not call it from interrupt |
| 493 | * context or with spin locks held. |
| 494 | * |
| 495 | * You must call rhashtable_walk_exit if this function returns |
| 496 | * successfully. |
| 497 | */ |
| 498 | int rhashtable_walk_init(struct rhashtable *ht, struct rhashtable_iter *iter) |
| 499 | { |
| 500 | iter->ht = ht; |
| 501 | iter->p = NULL; |
| 502 | iter->slot = 0; |
| 503 | iter->skip = 0; |
| 504 | |
| 505 | iter->walker = kmalloc(sizeof(*iter->walker), GFP_KERNEL); |
| 506 | if (!iter->walker) |
| 507 | return -ENOMEM; |
| 508 | |
| 509 | mutex_lock(&ht->mutex); |
Herbert Xu | eddee5ba | 2015-03-14 13:57:20 +1100 | [diff] [blame] | 510 | iter->walker->tbl = rht_dereference(ht->tbl, ht); |
| 511 | list_add(&iter->walker->list, &iter->walker->tbl->walkers); |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 512 | mutex_unlock(&ht->mutex); |
| 513 | |
| 514 | return 0; |
| 515 | } |
| 516 | EXPORT_SYMBOL_GPL(rhashtable_walk_init); |
| 517 | |
| 518 | /** |
| 519 | * rhashtable_walk_exit - Free an iterator |
| 520 | * @iter: Hash table Iterator |
| 521 | * |
| 522 | * This function frees resources allocated by rhashtable_walk_init. |
| 523 | */ |
| 524 | void rhashtable_walk_exit(struct rhashtable_iter *iter) |
| 525 | { |
| 526 | mutex_lock(&iter->ht->mutex); |
Herbert Xu | eddee5ba | 2015-03-14 13:57:20 +1100 | [diff] [blame] | 527 | if (iter->walker->tbl) |
| 528 | list_del(&iter->walker->list); |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 529 | mutex_unlock(&iter->ht->mutex); |
| 530 | kfree(iter->walker); |
| 531 | } |
| 532 | EXPORT_SYMBOL_GPL(rhashtable_walk_exit); |
| 533 | |
| 534 | /** |
| 535 | * rhashtable_walk_start - Start a hash table walk |
| 536 | * @iter: Hash table iterator |
| 537 | * |
| 538 | * Start a hash table walk. Note that we take the RCU lock in all |
| 539 | * cases including when we return an error. So you must always call |
| 540 | * rhashtable_walk_stop to clean up. |
| 541 | * |
| 542 | * Returns zero if successful. |
| 543 | * |
| 544 | * Returns -EAGAIN if resize event occured. Note that the iterator |
| 545 | * will rewind back to the beginning and you may use it immediately |
| 546 | * by calling rhashtable_walk_next. |
| 547 | */ |
| 548 | int rhashtable_walk_start(struct rhashtable_iter *iter) |
Thomas Graf | db4374f | 2015-03-16 10:42:27 +0100 | [diff] [blame] | 549 | __acquires(RCU) |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 550 | { |
Herbert Xu | eddee5ba | 2015-03-14 13:57:20 +1100 | [diff] [blame] | 551 | struct rhashtable *ht = iter->ht; |
| 552 | |
| 553 | mutex_lock(&ht->mutex); |
| 554 | |
| 555 | if (iter->walker->tbl) |
| 556 | list_del(&iter->walker->list); |
| 557 | |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 558 | rcu_read_lock(); |
| 559 | |
Herbert Xu | eddee5ba | 2015-03-14 13:57:20 +1100 | [diff] [blame] | 560 | mutex_unlock(&ht->mutex); |
| 561 | |
| 562 | if (!iter->walker->tbl) { |
| 563 | iter->walker->tbl = rht_dereference_rcu(ht->tbl, ht); |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 564 | return -EAGAIN; |
| 565 | } |
| 566 | |
| 567 | return 0; |
| 568 | } |
| 569 | EXPORT_SYMBOL_GPL(rhashtable_walk_start); |
| 570 | |
| 571 | /** |
| 572 | * rhashtable_walk_next - Return the next object and advance the iterator |
| 573 | * @iter: Hash table iterator |
| 574 | * |
| 575 | * Note that you must call rhashtable_walk_stop when you are finished |
| 576 | * with the walk. |
| 577 | * |
| 578 | * Returns the next object or NULL when the end of the table is reached. |
| 579 | * |
| 580 | * Returns -EAGAIN if resize event occured. Note that the iterator |
| 581 | * will rewind back to the beginning and you may continue to use it. |
| 582 | */ |
| 583 | void *rhashtable_walk_next(struct rhashtable_iter *iter) |
| 584 | { |
Herbert Xu | eddee5ba | 2015-03-14 13:57:20 +1100 | [diff] [blame] | 585 | struct bucket_table *tbl = iter->walker->tbl; |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 586 | struct rhashtable *ht = iter->ht; |
| 587 | struct rhash_head *p = iter->p; |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 588 | |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 589 | if (p) { |
| 590 | p = rht_dereference_bucket_rcu(p->next, tbl, iter->slot); |
| 591 | goto next; |
| 592 | } |
| 593 | |
| 594 | for (; iter->slot < tbl->size; iter->slot++) { |
| 595 | int skip = iter->skip; |
| 596 | |
| 597 | rht_for_each_rcu(p, tbl, iter->slot) { |
| 598 | if (!skip) |
| 599 | break; |
| 600 | skip--; |
| 601 | } |
| 602 | |
| 603 | next: |
| 604 | if (!rht_is_a_nulls(p)) { |
| 605 | iter->skip++; |
| 606 | iter->p = p; |
Thomas Graf | c936a79 | 2015-05-05 02:22:53 +0200 | [diff] [blame] | 607 | return rht_obj(ht, p); |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 608 | } |
| 609 | |
| 610 | iter->skip = 0; |
| 611 | } |
| 612 | |
Herbert Xu | d88252f | 2015-03-24 00:50:19 +1100 | [diff] [blame] | 613 | /* Ensure we see any new tables. */ |
| 614 | smp_rmb(); |
| 615 | |
Herbert Xu | c4db884 | 2015-03-14 13:57:25 +1100 | [diff] [blame] | 616 | iter->walker->tbl = rht_dereference_rcu(tbl->future_tbl, ht); |
| 617 | if (iter->walker->tbl) { |
Herbert Xu | eddee5ba | 2015-03-14 13:57:20 +1100 | [diff] [blame] | 618 | iter->slot = 0; |
| 619 | iter->skip = 0; |
| 620 | return ERR_PTR(-EAGAIN); |
| 621 | } |
| 622 | |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 623 | iter->p = NULL; |
| 624 | |
Thomas Graf | c936a79 | 2015-05-05 02:22:53 +0200 | [diff] [blame] | 625 | return NULL; |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 626 | } |
| 627 | EXPORT_SYMBOL_GPL(rhashtable_walk_next); |
| 628 | |
| 629 | /** |
| 630 | * rhashtable_walk_stop - Finish a hash table walk |
| 631 | * @iter: Hash table iterator |
| 632 | * |
| 633 | * Finish a hash table walk. |
| 634 | */ |
| 635 | void rhashtable_walk_stop(struct rhashtable_iter *iter) |
Thomas Graf | db4374f | 2015-03-16 10:42:27 +0100 | [diff] [blame] | 636 | __releases(RCU) |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 637 | { |
Herbert Xu | eddee5ba | 2015-03-14 13:57:20 +1100 | [diff] [blame] | 638 | struct rhashtable *ht; |
| 639 | struct bucket_table *tbl = iter->walker->tbl; |
| 640 | |
Herbert Xu | eddee5ba | 2015-03-14 13:57:20 +1100 | [diff] [blame] | 641 | if (!tbl) |
Herbert Xu | 963ecbd | 2015-03-15 21:12:04 +1100 | [diff] [blame] | 642 | goto out; |
Herbert Xu | eddee5ba | 2015-03-14 13:57:20 +1100 | [diff] [blame] | 643 | |
| 644 | ht = iter->ht; |
| 645 | |
Herbert Xu | ba7c95e | 2015-03-24 09:53:17 +1100 | [diff] [blame] | 646 | spin_lock(&ht->lock); |
Herbert Xu | c4db884 | 2015-03-14 13:57:25 +1100 | [diff] [blame] | 647 | if (tbl->rehash < tbl->size) |
Herbert Xu | eddee5ba | 2015-03-14 13:57:20 +1100 | [diff] [blame] | 648 | list_add(&iter->walker->list, &tbl->walkers); |
| 649 | else |
| 650 | iter->walker->tbl = NULL; |
Herbert Xu | ba7c95e | 2015-03-24 09:53:17 +1100 | [diff] [blame] | 651 | spin_unlock(&ht->lock); |
Herbert Xu | eddee5ba | 2015-03-14 13:57:20 +1100 | [diff] [blame] | 652 | |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 653 | iter->p = NULL; |
Herbert Xu | 963ecbd | 2015-03-15 21:12:04 +1100 | [diff] [blame] | 654 | |
| 655 | out: |
| 656 | rcu_read_unlock(); |
Herbert Xu | f2dba9c | 2015-02-04 07:33:23 +1100 | [diff] [blame] | 657 | } |
| 658 | EXPORT_SYMBOL_GPL(rhashtable_walk_stop); |
| 659 | |
Herbert Xu | 488fb86e | 2015-03-20 21:56:59 +1100 | [diff] [blame] | 660 | static size_t rounded_hashtable_size(const struct rhashtable_params *params) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 661 | { |
Ying Xue | 9400017 | 2014-09-03 09:22:36 +0800 | [diff] [blame] | 662 | return max(roundup_pow_of_two(params->nelem_hint * 4 / 3), |
Herbert Xu | e2e21c1 | 2015-03-18 20:01:21 +1100 | [diff] [blame] | 663 | (unsigned long)params->min_size); |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 664 | } |
| 665 | |
Herbert Xu | 31ccde2 | 2015-03-24 00:50:21 +1100 | [diff] [blame] | 666 | static u32 rhashtable_jhash2(const void *key, u32 length, u32 seed) |
| 667 | { |
| 668 | return jhash2(key, length, seed); |
| 669 | } |
| 670 | |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 671 | /** |
| 672 | * rhashtable_init - initialize a new hash table |
| 673 | * @ht: hash table to be initialized |
| 674 | * @params: configuration parameters |
| 675 | * |
| 676 | * Initializes a new hash table based on the provided configuration |
| 677 | * parameters. A table can be configured either with a variable or |
| 678 | * fixed length key: |
| 679 | * |
| 680 | * Configuration Example 1: Fixed length keys |
| 681 | * struct test_obj { |
| 682 | * int key; |
| 683 | * void * my_member; |
| 684 | * struct rhash_head node; |
| 685 | * }; |
| 686 | * |
| 687 | * struct rhashtable_params params = { |
| 688 | * .head_offset = offsetof(struct test_obj, node), |
| 689 | * .key_offset = offsetof(struct test_obj, key), |
| 690 | * .key_len = sizeof(int), |
Daniel Borkmann | 8754589 | 2014-12-10 16:33:11 +0100 | [diff] [blame] | 691 | * .hashfn = jhash, |
Thomas Graf | f89bd6f | 2015-01-02 23:00:21 +0100 | [diff] [blame] | 692 | * .nulls_base = (1U << RHT_BASE_SHIFT), |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 693 | * }; |
| 694 | * |
| 695 | * Configuration Example 2: Variable length keys |
| 696 | * struct test_obj { |
| 697 | * [...] |
| 698 | * struct rhash_head node; |
| 699 | * }; |
| 700 | * |
Patrick McHardy | 49f7b33 | 2015-03-25 13:07:45 +0000 | [diff] [blame] | 701 | * u32 my_hash_fn(const void *data, u32 len, u32 seed) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 702 | * { |
| 703 | * struct test_obj *obj = data; |
| 704 | * |
| 705 | * return [... hash ...]; |
| 706 | * } |
| 707 | * |
| 708 | * struct rhashtable_params params = { |
| 709 | * .head_offset = offsetof(struct test_obj, node), |
Daniel Borkmann | 8754589 | 2014-12-10 16:33:11 +0100 | [diff] [blame] | 710 | * .hashfn = jhash, |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 711 | * .obj_hashfn = my_hash_fn, |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 712 | * }; |
| 713 | */ |
Herbert Xu | 488fb86e | 2015-03-20 21:56:59 +1100 | [diff] [blame] | 714 | int rhashtable_init(struct rhashtable *ht, |
| 715 | const struct rhashtable_params *params) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 716 | { |
| 717 | struct bucket_table *tbl; |
| 718 | size_t size; |
| 719 | |
| 720 | size = HASH_DEFAULT_SIZE; |
| 721 | |
Herbert Xu | 31ccde2 | 2015-03-24 00:50:21 +1100 | [diff] [blame] | 722 | if ((!params->key_len && !params->obj_hashfn) || |
Herbert Xu | 02fd97c | 2015-03-20 21:57:00 +1100 | [diff] [blame] | 723 | (params->obj_hashfn && !params->obj_cmpfn)) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 724 | return -EINVAL; |
| 725 | |
Thomas Graf | f89bd6f | 2015-01-02 23:00:21 +0100 | [diff] [blame] | 726 | if (params->nulls_base && params->nulls_base < (1U << RHT_BASE_SHIFT)) |
| 727 | return -EINVAL; |
| 728 | |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 729 | if (params->nelem_hint) |
Ying Xue | 9400017 | 2014-09-03 09:22:36 +0800 | [diff] [blame] | 730 | size = rounded_hashtable_size(params); |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 731 | |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 732 | memset(ht, 0, sizeof(*ht)); |
| 733 | mutex_init(&ht->mutex); |
Herbert Xu | ba7c95e | 2015-03-24 09:53:17 +1100 | [diff] [blame] | 734 | spin_lock_init(&ht->lock); |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 735 | memcpy(&ht->p, params, sizeof(*params)); |
| 736 | |
Thomas Graf | a998f71 | 2015-03-19 22:31:13 +0000 | [diff] [blame] | 737 | if (params->min_size) |
| 738 | ht->p.min_size = roundup_pow_of_two(params->min_size); |
| 739 | |
| 740 | if (params->max_size) |
| 741 | ht->p.max_size = rounddown_pow_of_two(params->max_size); |
| 742 | |
Herbert Xu | 07ee072 | 2015-05-15 11:30:47 +0800 | [diff] [blame] | 743 | if (params->insecure_max_entries) |
| 744 | ht->p.insecure_max_entries = |
| 745 | rounddown_pow_of_two(params->insecure_max_entries); |
| 746 | else |
| 747 | ht->p.insecure_max_entries = ht->p.max_size * 2; |
| 748 | |
Herbert Xu | 488fb86e | 2015-03-20 21:56:59 +1100 | [diff] [blame] | 749 | ht->p.min_size = max(ht->p.min_size, HASH_MIN_SIZE); |
Thomas Graf | a998f71 | 2015-03-19 22:31:13 +0000 | [diff] [blame] | 750 | |
Herbert Xu | 27ed44a | 2015-03-24 13:37:30 +1100 | [diff] [blame] | 751 | /* The maximum (not average) chain length grows with the |
| 752 | * size of the hash table, at a rate of (log N)/(log log N). |
| 753 | * The value of 16 is selected so that even if the hash |
| 754 | * table grew to 2^32 you would not expect the maximum |
| 755 | * chain length to exceed it unless we are under attack |
| 756 | * (or extremely unlucky). |
| 757 | * |
| 758 | * As this limit is only to detect attacks, we don't need |
| 759 | * to set it to a lower value as you'd need the chain |
| 760 | * length to vastly exceed 16 to have any real effect |
| 761 | * on the system. |
| 762 | */ |
Herbert Xu | ccd57b1 | 2015-03-24 00:50:28 +1100 | [diff] [blame] | 763 | if (!params->insecure_elasticity) |
| 764 | ht->elasticity = 16; |
| 765 | |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 766 | if (params->locks_mul) |
| 767 | ht->p.locks_mul = roundup_pow_of_two(params->locks_mul); |
| 768 | else |
| 769 | ht->p.locks_mul = BUCKET_LOCKS_PER_CPU; |
| 770 | |
Herbert Xu | 31ccde2 | 2015-03-24 00:50:21 +1100 | [diff] [blame] | 771 | ht->key_len = ht->p.key_len; |
| 772 | if (!params->hashfn) { |
| 773 | ht->p.hashfn = jhash; |
| 774 | |
| 775 | if (!(ht->key_len & (sizeof(u32) - 1))) { |
| 776 | ht->key_len /= sizeof(u32); |
| 777 | ht->p.hashfn = rhashtable_jhash2; |
| 778 | } |
| 779 | } |
| 780 | |
Herbert Xu | b9ecfda | 2015-03-24 00:50:27 +1100 | [diff] [blame] | 781 | tbl = bucket_table_alloc(ht, size, GFP_KERNEL); |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 782 | if (tbl == NULL) |
| 783 | return -ENOMEM; |
| 784 | |
Ying Xue | 545a148e | 2015-01-07 13:41:57 +0800 | [diff] [blame] | 785 | atomic_set(&ht->nelems, 0); |
Daniel Borkmann | a5b6846 | 2015-03-12 15:28:40 +0100 | [diff] [blame] | 786 | |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 787 | RCU_INIT_POINTER(ht->tbl, tbl); |
| 788 | |
Daniel Borkmann | 4c4b52d | 2015-02-25 16:31:54 +0100 | [diff] [blame] | 789 | INIT_WORK(&ht->run_work, rht_deferred_worker); |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 790 | |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 791 | return 0; |
| 792 | } |
| 793 | EXPORT_SYMBOL_GPL(rhashtable_init); |
| 794 | |
| 795 | /** |
Thomas Graf | 6b6f302 | 2015-03-24 14:18:20 +0100 | [diff] [blame] | 796 | * rhashtable_free_and_destroy - free elements and destroy hash table |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 797 | * @ht: the hash table to destroy |
Thomas Graf | 6b6f302 | 2015-03-24 14:18:20 +0100 | [diff] [blame] | 798 | * @free_fn: callback to release resources of element |
| 799 | * @arg: pointer passed to free_fn |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 800 | * |
Thomas Graf | 6b6f302 | 2015-03-24 14:18:20 +0100 | [diff] [blame] | 801 | * Stops an eventual async resize. If defined, invokes free_fn for each |
| 802 | * element to releasal resources. Please note that RCU protected |
| 803 | * readers may still be accessing the elements. Releasing of resources |
| 804 | * must occur in a compatible manner. Then frees the bucket array. |
| 805 | * |
| 806 | * This function will eventually sleep to wait for an async resize |
| 807 | * to complete. The caller is responsible that no further write operations |
| 808 | * occurs in parallel. |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 809 | */ |
Thomas Graf | 6b6f302 | 2015-03-24 14:18:20 +0100 | [diff] [blame] | 810 | void rhashtable_free_and_destroy(struct rhashtable *ht, |
| 811 | void (*free_fn)(void *ptr, void *arg), |
| 812 | void *arg) |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 813 | { |
Thomas Graf | 6b6f302 | 2015-03-24 14:18:20 +0100 | [diff] [blame] | 814 | const struct bucket_table *tbl; |
| 815 | unsigned int i; |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 816 | |
Daniel Borkmann | 4c4b52d | 2015-02-25 16:31:54 +0100 | [diff] [blame] | 817 | cancel_work_sync(&ht->run_work); |
Ying Xue | 57699a4 | 2015-01-16 11:13:09 +0800 | [diff] [blame] | 818 | |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 819 | mutex_lock(&ht->mutex); |
Thomas Graf | 6b6f302 | 2015-03-24 14:18:20 +0100 | [diff] [blame] | 820 | tbl = rht_dereference(ht->tbl, ht); |
| 821 | if (free_fn) { |
| 822 | for (i = 0; i < tbl->size; i++) { |
| 823 | struct rhash_head *pos, *next; |
| 824 | |
| 825 | for (pos = rht_dereference(tbl->buckets[i], ht), |
| 826 | next = !rht_is_a_nulls(pos) ? |
| 827 | rht_dereference(pos->next, ht) : NULL; |
| 828 | !rht_is_a_nulls(pos); |
| 829 | pos = next, |
| 830 | next = !rht_is_a_nulls(pos) ? |
| 831 | rht_dereference(pos->next, ht) : NULL) |
| 832 | free_fn(rht_obj(ht, pos), arg); |
| 833 | } |
| 834 | } |
| 835 | |
| 836 | bucket_table_free(tbl); |
Thomas Graf | 97defe1 | 2015-01-02 23:00:20 +0100 | [diff] [blame] | 837 | mutex_unlock(&ht->mutex); |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 838 | } |
Thomas Graf | 6b6f302 | 2015-03-24 14:18:20 +0100 | [diff] [blame] | 839 | EXPORT_SYMBOL_GPL(rhashtable_free_and_destroy); |
| 840 | |
| 841 | void rhashtable_destroy(struct rhashtable *ht) |
| 842 | { |
| 843 | return rhashtable_free_and_destroy(ht, NULL, NULL); |
| 844 | } |
Thomas Graf | 7e1e776 | 2014-08-02 11:47:44 +0200 | [diff] [blame] | 845 | EXPORT_SYMBOL_GPL(rhashtable_destroy); |