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854 lines
21 KiB
C
854 lines
21 KiB
C
/*
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* Resizable, Scalable, Concurrent Hash Table
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*
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* Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
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* Copyright (c) 2014-2015 Thomas Graf <tgraf@suug.ch>
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* Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net>
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*
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* Code partially derived from nft_hash
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* Rewritten with rehash code from br_multicast plus single list
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* pointer as suggested by Josh Triplett
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/atomic.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/log2.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/vmalloc.h>
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#include <linux/mm.h>
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#include <linux/jhash.h>
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#include <linux/random.h>
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#include <linux/rhashtable.h>
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#include <linux/err.h>
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#include <linux/export.h>
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#define HASH_DEFAULT_SIZE 64UL
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#define HASH_MIN_SIZE 4U
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#define BUCKET_LOCKS_PER_CPU 128UL
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static u32 head_hashfn(struct rhashtable *ht,
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const struct bucket_table *tbl,
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const struct rhash_head *he)
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{
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return rht_head_hashfn(ht, tbl, he, ht->p);
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}
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#ifdef CONFIG_PROVE_LOCKING
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#define ASSERT_RHT_MUTEX(HT) BUG_ON(!lockdep_rht_mutex_is_held(HT))
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int lockdep_rht_mutex_is_held(struct rhashtable *ht)
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{
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return (debug_locks) ? lockdep_is_held(&ht->mutex) : 1;
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}
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EXPORT_SYMBOL_GPL(lockdep_rht_mutex_is_held);
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int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash)
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{
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spinlock_t *lock = rht_bucket_lock(tbl, hash);
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return (debug_locks) ? lockdep_is_held(lock) : 1;
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}
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EXPORT_SYMBOL_GPL(lockdep_rht_bucket_is_held);
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#else
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#define ASSERT_RHT_MUTEX(HT)
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#endif
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static int alloc_bucket_locks(struct rhashtable *ht, struct bucket_table *tbl,
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gfp_t gfp)
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{
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unsigned int i, size;
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#if defined(CONFIG_PROVE_LOCKING)
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unsigned int nr_pcpus = 2;
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#else
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unsigned int nr_pcpus = num_possible_cpus();
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#endif
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nr_pcpus = min_t(unsigned int, nr_pcpus, 32UL);
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size = roundup_pow_of_two(nr_pcpus * ht->p.locks_mul);
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/* Never allocate more than 0.5 locks per bucket */
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size = min_t(unsigned int, size, tbl->size >> 1);
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if (sizeof(spinlock_t) != 0) {
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#ifdef CONFIG_NUMA
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if (size * sizeof(spinlock_t) > PAGE_SIZE &&
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gfp == GFP_KERNEL)
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tbl->locks = vmalloc(size * sizeof(spinlock_t));
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else
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#endif
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tbl->locks = kmalloc_array(size, sizeof(spinlock_t),
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gfp);
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if (!tbl->locks)
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return -ENOMEM;
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for (i = 0; i < size; i++)
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spin_lock_init(&tbl->locks[i]);
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}
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tbl->locks_mask = size - 1;
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return 0;
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}
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static void bucket_table_free(const struct bucket_table *tbl)
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{
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if (tbl)
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kvfree(tbl->locks);
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kvfree(tbl);
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}
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static void bucket_table_free_rcu(struct rcu_head *head)
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{
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bucket_table_free(container_of(head, struct bucket_table, rcu));
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}
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static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
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size_t nbuckets,
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gfp_t gfp)
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{
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struct bucket_table *tbl = NULL;
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size_t size;
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int i;
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size = sizeof(*tbl) + nbuckets * sizeof(tbl->buckets[0]);
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if (size <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER) ||
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gfp != GFP_KERNEL)
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tbl = kzalloc(size, gfp | __GFP_NOWARN | __GFP_NORETRY);
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if (tbl == NULL && gfp == GFP_KERNEL)
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tbl = vzalloc(size);
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if (tbl == NULL)
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return NULL;
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tbl->size = nbuckets;
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if (alloc_bucket_locks(ht, tbl, gfp) < 0) {
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bucket_table_free(tbl);
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return NULL;
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}
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INIT_LIST_HEAD(&tbl->walkers);
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get_random_bytes(&tbl->hash_rnd, sizeof(tbl->hash_rnd));
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for (i = 0; i < nbuckets; i++)
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INIT_RHT_NULLS_HEAD(tbl->buckets[i], ht, i);
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return tbl;
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}
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static struct bucket_table *rhashtable_last_table(struct rhashtable *ht,
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struct bucket_table *tbl)
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{
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struct bucket_table *new_tbl;
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do {
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new_tbl = tbl;
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tbl = rht_dereference_rcu(tbl->future_tbl, ht);
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} while (tbl);
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return new_tbl;
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}
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static int rhashtable_rehash_one(struct rhashtable *ht, unsigned int old_hash)
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{
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struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
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struct bucket_table *new_tbl = rhashtable_last_table(ht,
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rht_dereference_rcu(old_tbl->future_tbl, ht));
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struct rhash_head __rcu **pprev = &old_tbl->buckets[old_hash];
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int err = -ENOENT;
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struct rhash_head *head, *next, *entry;
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spinlock_t *new_bucket_lock;
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unsigned int new_hash;
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rht_for_each(entry, old_tbl, old_hash) {
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err = 0;
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next = rht_dereference_bucket(entry->next, old_tbl, old_hash);
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if (rht_is_a_nulls(next))
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break;
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pprev = &entry->next;
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}
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if (err)
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goto out;
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new_hash = head_hashfn(ht, new_tbl, entry);
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new_bucket_lock = rht_bucket_lock(new_tbl, new_hash);
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spin_lock_nested(new_bucket_lock, SINGLE_DEPTH_NESTING);
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head = rht_dereference_bucket(new_tbl->buckets[new_hash],
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new_tbl, new_hash);
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RCU_INIT_POINTER(entry->next, head);
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rcu_assign_pointer(new_tbl->buckets[new_hash], entry);
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spin_unlock(new_bucket_lock);
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rcu_assign_pointer(*pprev, next);
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out:
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return err;
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}
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static void rhashtable_rehash_chain(struct rhashtable *ht,
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unsigned int old_hash)
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{
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struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
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spinlock_t *old_bucket_lock;
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old_bucket_lock = rht_bucket_lock(old_tbl, old_hash);
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spin_lock_bh(old_bucket_lock);
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while (!rhashtable_rehash_one(ht, old_hash))
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;
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old_tbl->rehash++;
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spin_unlock_bh(old_bucket_lock);
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}
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static int rhashtable_rehash_attach(struct rhashtable *ht,
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struct bucket_table *old_tbl,
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struct bucket_table *new_tbl)
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{
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/* Protect future_tbl using the first bucket lock. */
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spin_lock_bh(old_tbl->locks);
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/* Did somebody beat us to it? */
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if (rcu_access_pointer(old_tbl->future_tbl)) {
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spin_unlock_bh(old_tbl->locks);
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return -EEXIST;
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}
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/* Make insertions go into the new, empty table right away. Deletions
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* and lookups will be attempted in both tables until we synchronize.
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*/
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rcu_assign_pointer(old_tbl->future_tbl, new_tbl);
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spin_unlock_bh(old_tbl->locks);
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return 0;
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}
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static int rhashtable_rehash_table(struct rhashtable *ht)
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{
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struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
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struct bucket_table *new_tbl;
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struct rhashtable_walker *walker;
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unsigned int old_hash;
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new_tbl = rht_dereference(old_tbl->future_tbl, ht);
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if (!new_tbl)
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return 0;
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for (old_hash = 0; old_hash < old_tbl->size; old_hash++)
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rhashtable_rehash_chain(ht, old_hash);
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/* Publish the new table pointer. */
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rcu_assign_pointer(ht->tbl, new_tbl);
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spin_lock(&ht->lock);
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list_for_each_entry(walker, &old_tbl->walkers, list)
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walker->tbl = NULL;
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spin_unlock(&ht->lock);
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/* Wait for readers. All new readers will see the new
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* table, and thus no references to the old table will
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* remain.
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*/
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call_rcu(&old_tbl->rcu, bucket_table_free_rcu);
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return rht_dereference(new_tbl->future_tbl, ht) ? -EAGAIN : 0;
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}
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/**
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* rhashtable_expand - Expand hash table while allowing concurrent lookups
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* @ht: the hash table to expand
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*
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* A secondary bucket array is allocated and the hash entries are migrated.
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*
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* This function may only be called in a context where it is safe to call
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* synchronize_rcu(), e.g. not within a rcu_read_lock() section.
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*
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* The caller must ensure that no concurrent resizing occurs by holding
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* ht->mutex.
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*
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* It is valid to have concurrent insertions and deletions protected by per
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* bucket locks or concurrent RCU protected lookups and traversals.
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*/
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static int rhashtable_expand(struct rhashtable *ht)
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{
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struct bucket_table *new_tbl, *old_tbl = rht_dereference(ht->tbl, ht);
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int err;
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ASSERT_RHT_MUTEX(ht);
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old_tbl = rhashtable_last_table(ht, old_tbl);
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new_tbl = bucket_table_alloc(ht, old_tbl->size * 2, GFP_KERNEL);
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if (new_tbl == NULL)
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return -ENOMEM;
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err = rhashtable_rehash_attach(ht, old_tbl, new_tbl);
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if (err)
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bucket_table_free(new_tbl);
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return err;
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}
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/**
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* rhashtable_shrink - Shrink hash table while allowing concurrent lookups
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* @ht: the hash table to shrink
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*
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* This function shrinks the hash table to fit, i.e., the smallest
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* size would not cause it to expand right away automatically.
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*
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* The caller must ensure that no concurrent resizing occurs by holding
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* ht->mutex.
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*
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* The caller must ensure that no concurrent table mutations take place.
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* It is however valid to have concurrent lookups if they are RCU protected.
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*
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* It is valid to have concurrent insertions and deletions protected by per
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* bucket locks or concurrent RCU protected lookups and traversals.
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*/
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static int rhashtable_shrink(struct rhashtable *ht)
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{
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struct bucket_table *new_tbl, *old_tbl = rht_dereference(ht->tbl, ht);
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unsigned int size;
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int err;
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ASSERT_RHT_MUTEX(ht);
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size = roundup_pow_of_two(atomic_read(&ht->nelems) * 3 / 2);
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if (size < ht->p.min_size)
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size = ht->p.min_size;
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if (old_tbl->size <= size)
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return 0;
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if (rht_dereference(old_tbl->future_tbl, ht))
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return -EEXIST;
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new_tbl = bucket_table_alloc(ht, size, GFP_KERNEL);
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if (new_tbl == NULL)
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return -ENOMEM;
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err = rhashtable_rehash_attach(ht, old_tbl, new_tbl);
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if (err)
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bucket_table_free(new_tbl);
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return err;
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}
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static void rht_deferred_worker(struct work_struct *work)
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{
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struct rhashtable *ht;
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struct bucket_table *tbl;
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int err = 0;
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ht = container_of(work, struct rhashtable, run_work);
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mutex_lock(&ht->mutex);
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tbl = rht_dereference(ht->tbl, ht);
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tbl = rhashtable_last_table(ht, tbl);
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if (rht_grow_above_75(ht, tbl))
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rhashtable_expand(ht);
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else if (ht->p.automatic_shrinking && rht_shrink_below_30(ht, tbl))
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rhashtable_shrink(ht);
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err = rhashtable_rehash_table(ht);
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mutex_unlock(&ht->mutex);
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if (err)
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schedule_work(&ht->run_work);
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}
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static bool rhashtable_check_elasticity(struct rhashtable *ht,
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struct bucket_table *tbl,
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unsigned int hash)
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{
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unsigned int elasticity = ht->elasticity;
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struct rhash_head *head;
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rht_for_each(head, tbl, hash)
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if (!--elasticity)
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return true;
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return false;
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}
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int rhashtable_insert_rehash(struct rhashtable *ht,
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struct bucket_table *tbl)
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{
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struct bucket_table *old_tbl;
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struct bucket_table *new_tbl;
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unsigned int size;
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int err;
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old_tbl = rht_dereference_rcu(ht->tbl, ht);
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size = tbl->size;
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err = -EBUSY;
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if (rht_grow_above_75(ht, tbl))
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size *= 2;
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/* Do not schedule more than one rehash */
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else if (old_tbl != tbl)
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goto fail;
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err = -ENOMEM;
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new_tbl = bucket_table_alloc(ht, size, GFP_ATOMIC);
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if (new_tbl == NULL)
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goto fail;
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err = rhashtable_rehash_attach(ht, tbl, new_tbl);
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if (err) {
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bucket_table_free(new_tbl);
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if (err == -EEXIST)
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err = 0;
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} else
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schedule_work(&ht->run_work);
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return err;
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fail:
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/* Do not fail the insert if someone else did a rehash. */
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if (likely(rcu_dereference_raw(tbl->future_tbl)))
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return 0;
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/* Schedule async rehash to retry allocation in process context. */
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if (err == -ENOMEM)
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schedule_work(&ht->run_work);
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return err;
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}
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EXPORT_SYMBOL_GPL(rhashtable_insert_rehash);
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struct bucket_table *rhashtable_insert_slow(struct rhashtable *ht,
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const void *key,
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struct rhash_head *obj,
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struct bucket_table *tbl)
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{
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struct rhash_head *head;
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unsigned int hash;
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int err;
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tbl = rhashtable_last_table(ht, tbl);
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hash = head_hashfn(ht, tbl, obj);
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spin_lock_nested(rht_bucket_lock(tbl, hash), SINGLE_DEPTH_NESTING);
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err = -EEXIST;
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if (key && rhashtable_lookup_fast(ht, key, ht->p))
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goto exit;
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err = -E2BIG;
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if (unlikely(rht_grow_above_max(ht, tbl)))
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goto exit;
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err = -EAGAIN;
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if (rhashtable_check_elasticity(ht, tbl, hash) ||
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rht_grow_above_100(ht, tbl))
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goto exit;
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err = 0;
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head = rht_dereference_bucket(tbl->buckets[hash], tbl, hash);
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RCU_INIT_POINTER(obj->next, head);
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rcu_assign_pointer(tbl->buckets[hash], obj);
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atomic_inc(&ht->nelems);
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exit:
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spin_unlock(rht_bucket_lock(tbl, hash));
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if (err == 0)
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return NULL;
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else if (err == -EAGAIN)
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return tbl;
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else
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return ERR_PTR(err);
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}
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EXPORT_SYMBOL_GPL(rhashtable_insert_slow);
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/**
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* rhashtable_walk_init - Initialise an iterator
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* @ht: Table to walk over
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* @iter: Hash table Iterator
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*
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* This function prepares a hash table walk.
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*
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* Note that if you restart a walk after rhashtable_walk_stop you
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* may see the same object twice. Also, you may miss objects if
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* there are removals in between rhashtable_walk_stop and the next
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* call to rhashtable_walk_start.
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*
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* For a completely stable walk you should construct your own data
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* structure outside the hash table.
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*
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* This function may sleep so you must not call it from interrupt
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* context or with spin locks held.
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*
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* You must call rhashtable_walk_exit if this function returns
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* successfully.
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*/
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int rhashtable_walk_init(struct rhashtable *ht, struct rhashtable_iter *iter)
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{
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iter->ht = ht;
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iter->p = NULL;
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iter->slot = 0;
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iter->skip = 0;
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iter->walker = kmalloc(sizeof(*iter->walker), GFP_KERNEL);
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if (!iter->walker)
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return -ENOMEM;
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spin_lock(&ht->lock);
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iter->walker->tbl =
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rcu_dereference_protected(ht->tbl, lockdep_is_held(&ht->lock));
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list_add(&iter->walker->list, &iter->walker->tbl->walkers);
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spin_unlock(&ht->lock);
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return 0;
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}
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EXPORT_SYMBOL_GPL(rhashtable_walk_init);
|
|
|
|
/**
|
|
* rhashtable_walk_exit - Free an iterator
|
|
* @iter: Hash table Iterator
|
|
*
|
|
* This function frees resources allocated by rhashtable_walk_init.
|
|
*/
|
|
void rhashtable_walk_exit(struct rhashtable_iter *iter)
|
|
{
|
|
spin_lock(&iter->ht->lock);
|
|
if (iter->walker->tbl)
|
|
list_del(&iter->walker->list);
|
|
spin_unlock(&iter->ht->lock);
|
|
kfree(iter->walker);
|
|
}
|
|
EXPORT_SYMBOL_GPL(rhashtable_walk_exit);
|
|
|
|
/**
|
|
* rhashtable_walk_start - Start a hash table walk
|
|
* @iter: Hash table iterator
|
|
*
|
|
* Start a hash table walk. Note that we take the RCU lock in all
|
|
* cases including when we return an error. So you must always call
|
|
* rhashtable_walk_stop to clean up.
|
|
*
|
|
* Returns zero if successful.
|
|
*
|
|
* Returns -EAGAIN if resize event occured. Note that the iterator
|
|
* will rewind back to the beginning and you may use it immediately
|
|
* by calling rhashtable_walk_next.
|
|
*/
|
|
int rhashtable_walk_start(struct rhashtable_iter *iter)
|
|
__acquires(RCU)
|
|
{
|
|
struct rhashtable *ht = iter->ht;
|
|
|
|
rcu_read_lock();
|
|
|
|
spin_lock(&ht->lock);
|
|
if (iter->walker->tbl)
|
|
list_del(&iter->walker->list);
|
|
spin_unlock(&ht->lock);
|
|
|
|
if (!iter->walker->tbl) {
|
|
iter->walker->tbl = rht_dereference_rcu(ht->tbl, ht);
|
|
return -EAGAIN;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(rhashtable_walk_start);
|
|
|
|
/**
|
|
* rhashtable_walk_next - Return the next object and advance the iterator
|
|
* @iter: Hash table iterator
|
|
*
|
|
* Note that you must call rhashtable_walk_stop when you are finished
|
|
* with the walk.
|
|
*
|
|
* Returns the next object or NULL when the end of the table is reached.
|
|
*
|
|
* Returns -EAGAIN if resize event occured. Note that the iterator
|
|
* will rewind back to the beginning and you may continue to use it.
|
|
*/
|
|
void *rhashtable_walk_next(struct rhashtable_iter *iter)
|
|
{
|
|
struct bucket_table *tbl = iter->walker->tbl;
|
|
struct rhashtable *ht = iter->ht;
|
|
struct rhash_head *p = iter->p;
|
|
|
|
if (p) {
|
|
p = rht_dereference_bucket_rcu(p->next, tbl, iter->slot);
|
|
goto next;
|
|
}
|
|
|
|
for (; iter->slot < tbl->size; iter->slot++) {
|
|
int skip = iter->skip;
|
|
|
|
rht_for_each_rcu(p, tbl, iter->slot) {
|
|
if (!skip)
|
|
break;
|
|
skip--;
|
|
}
|
|
|
|
next:
|
|
if (!rht_is_a_nulls(p)) {
|
|
iter->skip++;
|
|
iter->p = p;
|
|
return rht_obj(ht, p);
|
|
}
|
|
|
|
iter->skip = 0;
|
|
}
|
|
|
|
iter->p = NULL;
|
|
|
|
/* Ensure we see any new tables. */
|
|
smp_rmb();
|
|
|
|
iter->walker->tbl = rht_dereference_rcu(tbl->future_tbl, ht);
|
|
if (iter->walker->tbl) {
|
|
iter->slot = 0;
|
|
iter->skip = 0;
|
|
return ERR_PTR(-EAGAIN);
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(rhashtable_walk_next);
|
|
|
|
/**
|
|
* rhashtable_walk_stop - Finish a hash table walk
|
|
* @iter: Hash table iterator
|
|
*
|
|
* Finish a hash table walk.
|
|
*/
|
|
void rhashtable_walk_stop(struct rhashtable_iter *iter)
|
|
__releases(RCU)
|
|
{
|
|
struct rhashtable *ht;
|
|
struct bucket_table *tbl = iter->walker->tbl;
|
|
|
|
if (!tbl)
|
|
goto out;
|
|
|
|
ht = iter->ht;
|
|
|
|
spin_lock(&ht->lock);
|
|
if (tbl->rehash < tbl->size)
|
|
list_add(&iter->walker->list, &tbl->walkers);
|
|
else
|
|
iter->walker->tbl = NULL;
|
|
spin_unlock(&ht->lock);
|
|
|
|
iter->p = NULL;
|
|
|
|
out:
|
|
rcu_read_unlock();
|
|
}
|
|
EXPORT_SYMBOL_GPL(rhashtable_walk_stop);
|
|
|
|
static size_t rounded_hashtable_size(const struct rhashtable_params *params)
|
|
{
|
|
return max(roundup_pow_of_two(params->nelem_hint * 4 / 3),
|
|
(unsigned long)params->min_size);
|
|
}
|
|
|
|
static u32 rhashtable_jhash2(const void *key, u32 length, u32 seed)
|
|
{
|
|
return jhash2(key, length, seed);
|
|
}
|
|
|
|
/**
|
|
* rhashtable_init - initialize a new hash table
|
|
* @ht: hash table to be initialized
|
|
* @params: configuration parameters
|
|
*
|
|
* Initializes a new hash table based on the provided configuration
|
|
* parameters. A table can be configured either with a variable or
|
|
* fixed length key:
|
|
*
|
|
* Configuration Example 1: Fixed length keys
|
|
* struct test_obj {
|
|
* int key;
|
|
* void * my_member;
|
|
* struct rhash_head node;
|
|
* };
|
|
*
|
|
* struct rhashtable_params params = {
|
|
* .head_offset = offsetof(struct test_obj, node),
|
|
* .key_offset = offsetof(struct test_obj, key),
|
|
* .key_len = sizeof(int),
|
|
* .hashfn = jhash,
|
|
* .nulls_base = (1U << RHT_BASE_SHIFT),
|
|
* };
|
|
*
|
|
* Configuration Example 2: Variable length keys
|
|
* struct test_obj {
|
|
* [...]
|
|
* struct rhash_head node;
|
|
* };
|
|
*
|
|
* u32 my_hash_fn(const void *data, u32 len, u32 seed)
|
|
* {
|
|
* struct test_obj *obj = data;
|
|
*
|
|
* return [... hash ...];
|
|
* }
|
|
*
|
|
* struct rhashtable_params params = {
|
|
* .head_offset = offsetof(struct test_obj, node),
|
|
* .hashfn = jhash,
|
|
* .obj_hashfn = my_hash_fn,
|
|
* };
|
|
*/
|
|
int rhashtable_init(struct rhashtable *ht,
|
|
const struct rhashtable_params *params)
|
|
{
|
|
struct bucket_table *tbl;
|
|
size_t size;
|
|
|
|
size = HASH_DEFAULT_SIZE;
|
|
|
|
if ((!params->key_len && !params->obj_hashfn) ||
|
|
(params->obj_hashfn && !params->obj_cmpfn))
|
|
return -EINVAL;
|
|
|
|
if (params->nulls_base && params->nulls_base < (1U << RHT_BASE_SHIFT))
|
|
return -EINVAL;
|
|
|
|
memset(ht, 0, sizeof(*ht));
|
|
mutex_init(&ht->mutex);
|
|
spin_lock_init(&ht->lock);
|
|
memcpy(&ht->p, params, sizeof(*params));
|
|
|
|
if (params->min_size)
|
|
ht->p.min_size = roundup_pow_of_two(params->min_size);
|
|
|
|
if (params->max_size)
|
|
ht->p.max_size = rounddown_pow_of_two(params->max_size);
|
|
|
|
if (params->insecure_max_entries)
|
|
ht->p.insecure_max_entries =
|
|
rounddown_pow_of_two(params->insecure_max_entries);
|
|
else
|
|
ht->p.insecure_max_entries = ht->p.max_size * 2;
|
|
|
|
ht->p.min_size = max(ht->p.min_size, HASH_MIN_SIZE);
|
|
|
|
if (params->nelem_hint)
|
|
size = rounded_hashtable_size(&ht->p);
|
|
|
|
/* The maximum (not average) chain length grows with the
|
|
* size of the hash table, at a rate of (log N)/(log log N).
|
|
* The value of 16 is selected so that even if the hash
|
|
* table grew to 2^32 you would not expect the maximum
|
|
* chain length to exceed it unless we are under attack
|
|
* (or extremely unlucky).
|
|
*
|
|
* As this limit is only to detect attacks, we don't need
|
|
* to set it to a lower value as you'd need the chain
|
|
* length to vastly exceed 16 to have any real effect
|
|
* on the system.
|
|
*/
|
|
if (!params->insecure_elasticity)
|
|
ht->elasticity = 16;
|
|
|
|
if (params->locks_mul)
|
|
ht->p.locks_mul = roundup_pow_of_two(params->locks_mul);
|
|
else
|
|
ht->p.locks_mul = BUCKET_LOCKS_PER_CPU;
|
|
|
|
ht->key_len = ht->p.key_len;
|
|
if (!params->hashfn) {
|
|
ht->p.hashfn = jhash;
|
|
|
|
if (!(ht->key_len & (sizeof(u32) - 1))) {
|
|
ht->key_len /= sizeof(u32);
|
|
ht->p.hashfn = rhashtable_jhash2;
|
|
}
|
|
}
|
|
|
|
tbl = bucket_table_alloc(ht, size, GFP_KERNEL);
|
|
if (tbl == NULL)
|
|
return -ENOMEM;
|
|
|
|
atomic_set(&ht->nelems, 0);
|
|
|
|
RCU_INIT_POINTER(ht->tbl, tbl);
|
|
|
|
INIT_WORK(&ht->run_work, rht_deferred_worker);
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(rhashtable_init);
|
|
|
|
/**
|
|
* rhashtable_free_and_destroy - free elements and destroy hash table
|
|
* @ht: the hash table to destroy
|
|
* @free_fn: callback to release resources of element
|
|
* @arg: pointer passed to free_fn
|
|
*
|
|
* Stops an eventual async resize. If defined, invokes free_fn for each
|
|
* element to releasal resources. Please note that RCU protected
|
|
* readers may still be accessing the elements. Releasing of resources
|
|
* must occur in a compatible manner. Then frees the bucket array.
|
|
*
|
|
* This function will eventually sleep to wait for an async resize
|
|
* to complete. The caller is responsible that no further write operations
|
|
* occurs in parallel.
|
|
*/
|
|
void rhashtable_free_and_destroy(struct rhashtable *ht,
|
|
void (*free_fn)(void *ptr, void *arg),
|
|
void *arg)
|
|
{
|
|
const struct bucket_table *tbl;
|
|
unsigned int i;
|
|
|
|
cancel_work_sync(&ht->run_work);
|
|
|
|
mutex_lock(&ht->mutex);
|
|
tbl = rht_dereference(ht->tbl, ht);
|
|
if (free_fn) {
|
|
for (i = 0; i < tbl->size; i++) {
|
|
struct rhash_head *pos, *next;
|
|
|
|
for (pos = rht_dereference(tbl->buckets[i], ht),
|
|
next = !rht_is_a_nulls(pos) ?
|
|
rht_dereference(pos->next, ht) : NULL;
|
|
!rht_is_a_nulls(pos);
|
|
pos = next,
|
|
next = !rht_is_a_nulls(pos) ?
|
|
rht_dereference(pos->next, ht) : NULL)
|
|
free_fn(rht_obj(ht, pos), arg);
|
|
}
|
|
}
|
|
|
|
bucket_table_free(tbl);
|
|
mutex_unlock(&ht->mutex);
|
|
}
|
|
EXPORT_SYMBOL_GPL(rhashtable_free_and_destroy);
|
|
|
|
void rhashtable_destroy(struct rhashtable *ht)
|
|
{
|
|
return rhashtable_free_and_destroy(ht, NULL, NULL);
|
|
}
|
|
EXPORT_SYMBOL_GPL(rhashtable_destroy);
|