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1241 lines
30 KiB
1241 lines
30 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Resizable, Scalable, Concurrent Hash Table |
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* |
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* Copyright (c) 2015 Herbert Xu <[email protected]> |
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* Copyright (c) 2014-2015 Thomas Graf <[email protected]> |
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* Copyright (c) 2008-2014 Patrick McHardy <[email protected]> |
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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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|
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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/rculist.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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|
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#define HASH_DEFAULT_SIZE 64UL |
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#define HASH_MIN_SIZE 4U |
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|
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union nested_table { |
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union nested_table __rcu *table; |
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struct rhash_lock_head __rcu *bucket; |
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}; |
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|
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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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|
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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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|
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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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|
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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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if (!debug_locks) |
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return 1; |
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if (unlikely(tbl->nest)) |
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return 1; |
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return bit_spin_is_locked(0, (unsigned long *)&tbl->buckets[hash]); |
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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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|
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static inline union nested_table *nested_table_top( |
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const struct bucket_table *tbl) |
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{ |
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/* The top-level bucket entry does not need RCU protection |
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* because it's set at the same time as tbl->nest. |
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*/ |
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return (void *)rcu_dereference_protected(tbl->buckets[0], 1); |
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} |
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|
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static void nested_table_free(union nested_table *ntbl, unsigned int size) |
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{ |
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const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *)); |
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const unsigned int len = 1 << shift; |
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unsigned int i; |
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|
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ntbl = rcu_dereference_protected(ntbl->table, 1); |
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if (!ntbl) |
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return; |
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|
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if (size > len) { |
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size >>= shift; |
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for (i = 0; i < len; i++) |
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nested_table_free(ntbl + i, size); |
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} |
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|
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kfree(ntbl); |
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} |
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|
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static void nested_bucket_table_free(const struct bucket_table *tbl) |
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{ |
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unsigned int size = tbl->size >> tbl->nest; |
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unsigned int len = 1 << tbl->nest; |
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union nested_table *ntbl; |
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unsigned int i; |
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ntbl = nested_table_top(tbl); |
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for (i = 0; i < len; i++) |
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nested_table_free(ntbl + i, size); |
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|
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kfree(ntbl); |
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} |
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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->nest) |
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nested_bucket_table_free(tbl); |
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|
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kvfree(tbl); |
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} |
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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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|
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static union nested_table *nested_table_alloc(struct rhashtable *ht, |
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union nested_table __rcu **prev, |
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bool leaf) |
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{ |
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union nested_table *ntbl; |
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int i; |
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|
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ntbl = rcu_dereference(*prev); |
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if (ntbl) |
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return ntbl; |
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ntbl = kzalloc(PAGE_SIZE, GFP_ATOMIC); |
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|
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if (ntbl && leaf) { |
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for (i = 0; i < PAGE_SIZE / sizeof(ntbl[0]); i++) |
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INIT_RHT_NULLS_HEAD(ntbl[i].bucket); |
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} |
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if (cmpxchg((union nested_table **)prev, NULL, ntbl) == NULL) |
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return ntbl; |
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/* Raced with another thread. */ |
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kfree(ntbl); |
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return rcu_dereference(*prev); |
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} |
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static struct bucket_table *nested_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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const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *)); |
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struct bucket_table *tbl; |
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size_t size; |
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|
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if (nbuckets < (1 << (shift + 1))) |
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return NULL; |
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size = sizeof(*tbl) + sizeof(tbl->buckets[0]); |
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tbl = kzalloc(size, gfp); |
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if (!tbl) |
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return NULL; |
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|
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if (!nested_table_alloc(ht, (union nested_table __rcu **)tbl->buckets, |
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false)) { |
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kfree(tbl); |
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return NULL; |
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} |
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tbl->nest = (ilog2(nbuckets) - 1) % shift + 1; |
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|
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return tbl; |
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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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static struct lock_class_key __key; |
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|
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tbl = kvzalloc(struct_size(tbl, buckets, nbuckets), gfp); |
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|
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size = nbuckets; |
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|
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if (tbl == NULL && (gfp & ~__GFP_NOFAIL) != GFP_KERNEL) { |
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tbl = nested_bucket_table_alloc(ht, nbuckets, gfp); |
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nbuckets = 0; |
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} |
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if (tbl == NULL) |
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return NULL; |
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lockdep_init_map(&tbl->dep_map, "rhashtable_bucket", &__key, 0); |
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tbl->size = size; |
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rcu_head_init(&tbl->rcu); |
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INIT_LIST_HEAD(&tbl->walkers); |
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tbl->hash_rnd = get_random_u32(); |
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|
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for (i = 0; i < nbuckets; i++) |
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INIT_RHT_NULLS_HEAD(tbl->buckets[i]); |
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|
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return tbl; |
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} |
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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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|
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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, |
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struct rhash_lock_head __rcu **bkt, |
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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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struct bucket_table *new_tbl = rhashtable_last_table(ht, old_tbl); |
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int err = -EAGAIN; |
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struct rhash_head *head, *next, *entry; |
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struct rhash_head __rcu **pprev = NULL; |
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unsigned int new_hash; |
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if (new_tbl->nest) |
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goto out; |
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err = -ENOENT; |
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rht_for_each_from(entry, rht_ptr(bkt, old_tbl, old_hash), |
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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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|
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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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rht_lock_nested(new_tbl, &new_tbl->buckets[new_hash], SINGLE_DEPTH_NESTING); |
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head = rht_ptr(new_tbl->buckets + new_hash, new_tbl, new_hash); |
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RCU_INIT_POINTER(entry->next, head); |
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rht_assign_unlock(new_tbl, &new_tbl->buckets[new_hash], entry); |
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if (pprev) |
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rcu_assign_pointer(*pprev, next); |
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else |
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/* Need to preserved the bit lock. */ |
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rht_assign_locked(bkt, next); |
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|
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out: |
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return err; |
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} |
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static int 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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struct rhash_lock_head __rcu **bkt = rht_bucket_var(old_tbl, old_hash); |
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int err; |
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if (!bkt) |
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return 0; |
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rht_lock(old_tbl, bkt); |
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while (!(err = rhashtable_rehash_one(ht, bkt, old_hash))) |
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; |
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if (err == -ENOENT) |
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err = 0; |
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rht_unlock(old_tbl, bkt); |
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|
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return err; |
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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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/* 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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* As cmpxchg() provides strong barriers, we do not need |
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* rcu_assign_pointer(). |
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*/ |
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|
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if (cmpxchg((struct bucket_table **)&old_tbl->future_tbl, NULL, |
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new_tbl) != NULL) |
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return -EEXIST; |
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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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int err; |
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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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err = rhashtable_rehash_chain(ht, old_hash); |
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if (err) |
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return err; |
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cond_resched(); |
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} |
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/* Publish the new table pointer. */ |
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rcu_assign_pointer(ht->tbl, new_tbl); |
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|
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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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|
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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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* We do this inside the locked region so that |
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* rhashtable_walk_stop() can use rcu_head_after_call_rcu() |
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* to check if it should not re-link the table. |
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*/ |
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call_rcu(&old_tbl->rcu, bucket_table_free_rcu); |
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spin_unlock(&ht->lock); |
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return rht_dereference(new_tbl->future_tbl, ht) ? -EAGAIN : 0; |
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} |
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static int rhashtable_rehash_alloc(struct rhashtable *ht, |
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struct bucket_table *old_tbl, |
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unsigned int size) |
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{ |
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struct bucket_table *new_tbl; |
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int err; |
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|
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ASSERT_RHT_MUTEX(ht); |
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|
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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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|
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return err; |
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} |
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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 *old_tbl = rht_dereference(ht->tbl, ht); |
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unsigned int nelems = atomic_read(&ht->nelems); |
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unsigned int size = 0; |
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|
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if (nelems) |
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size = roundup_pow_of_two(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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|
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if (old_tbl->size <= size) |
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return 0; |
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|
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if (rht_dereference(old_tbl->future_tbl, ht)) |
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return -EEXIST; |
|
|
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return rhashtable_rehash_alloc(ht, old_tbl, size); |
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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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|
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ht = container_of(work, struct rhashtable, run_work); |
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mutex_lock(&ht->mutex); |
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|
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tbl = rht_dereference(ht->tbl, ht); |
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tbl = rhashtable_last_table(ht, tbl); |
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|
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if (rht_grow_above_75(ht, tbl)) |
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err = rhashtable_rehash_alloc(ht, tbl, tbl->size * 2); |
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else if (ht->p.automatic_shrinking && rht_shrink_below_30(ht, tbl)) |
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err = rhashtable_shrink(ht); |
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else if (tbl->nest) |
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err = rhashtable_rehash_alloc(ht, tbl, tbl->size); |
|
|
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if (!err || err == -EEXIST) { |
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int nerr; |
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|
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nerr = rhashtable_rehash_table(ht); |
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err = err ?: nerr; |
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} |
|
|
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mutex_unlock(&ht->mutex); |
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|
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if (err) |
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schedule_work(&ht->run_work); |
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} |
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|
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static 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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|
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size = tbl->size; |
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|
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err = -EBUSY; |
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|
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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 | __GFP_NOWARN); |
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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_access_pointer(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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static void *rhashtable_lookup_one(struct rhashtable *ht, |
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struct rhash_lock_head __rcu **bkt, |
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struct bucket_table *tbl, unsigned int hash, |
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const void *key, struct rhash_head *obj) |
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{ |
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struct rhashtable_compare_arg arg = { |
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.ht = ht, |
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.key = key, |
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}; |
|
struct rhash_head __rcu **pprev = NULL; |
|
struct rhash_head *head; |
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int elasticity; |
|
|
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elasticity = RHT_ELASTICITY; |
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rht_for_each_from(head, rht_ptr(bkt, tbl, hash), tbl, hash) { |
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struct rhlist_head *list; |
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struct rhlist_head *plist; |
|
|
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elasticity--; |
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if (!key || |
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(ht->p.obj_cmpfn ? |
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ht->p.obj_cmpfn(&arg, rht_obj(ht, head)) : |
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rhashtable_compare(&arg, rht_obj(ht, head)))) { |
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pprev = &head->next; |
|
continue; |
|
} |
|
|
|
if (!ht->rhlist) |
|
return rht_obj(ht, head); |
|
|
|
list = container_of(obj, struct rhlist_head, rhead); |
|
plist = container_of(head, struct rhlist_head, rhead); |
|
|
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RCU_INIT_POINTER(list->next, plist); |
|
head = rht_dereference_bucket(head->next, tbl, hash); |
|
RCU_INIT_POINTER(list->rhead.next, head); |
|
if (pprev) |
|
rcu_assign_pointer(*pprev, obj); |
|
else |
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/* Need to preserve the bit lock */ |
|
rht_assign_locked(bkt, obj); |
|
|
|
return NULL; |
|
} |
|
|
|
if (elasticity <= 0) |
|
return ERR_PTR(-EAGAIN); |
|
|
|
return ERR_PTR(-ENOENT); |
|
} |
|
|
|
static struct bucket_table *rhashtable_insert_one( |
|
struct rhashtable *ht, struct rhash_lock_head __rcu **bkt, |
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struct bucket_table *tbl, unsigned int hash, struct rhash_head *obj, |
|
void *data) |
|
{ |
|
struct bucket_table *new_tbl; |
|
struct rhash_head *head; |
|
|
|
if (!IS_ERR_OR_NULL(data)) |
|
return ERR_PTR(-EEXIST); |
|
|
|
if (PTR_ERR(data) != -EAGAIN && PTR_ERR(data) != -ENOENT) |
|
return ERR_CAST(data); |
|
|
|
new_tbl = rht_dereference_rcu(tbl->future_tbl, ht); |
|
if (new_tbl) |
|
return new_tbl; |
|
|
|
if (PTR_ERR(data) != -ENOENT) |
|
return ERR_CAST(data); |
|
|
|
if (unlikely(rht_grow_above_max(ht, tbl))) |
|
return ERR_PTR(-E2BIG); |
|
|
|
if (unlikely(rht_grow_above_100(ht, tbl))) |
|
return ERR_PTR(-EAGAIN); |
|
|
|
head = rht_ptr(bkt, tbl, hash); |
|
|
|
RCU_INIT_POINTER(obj->next, head); |
|
if (ht->rhlist) { |
|
struct rhlist_head *list; |
|
|
|
list = container_of(obj, struct rhlist_head, rhead); |
|
RCU_INIT_POINTER(list->next, NULL); |
|
} |
|
|
|
/* bkt is always the head of the list, so it holds |
|
* the lock, which we need to preserve |
|
*/ |
|
rht_assign_locked(bkt, obj); |
|
|
|
atomic_inc(&ht->nelems); |
|
if (rht_grow_above_75(ht, tbl)) |
|
schedule_work(&ht->run_work); |
|
|
|
return NULL; |
|
} |
|
|
|
static void *rhashtable_try_insert(struct rhashtable *ht, const void *key, |
|
struct rhash_head *obj) |
|
{ |
|
struct bucket_table *new_tbl; |
|
struct bucket_table *tbl; |
|
struct rhash_lock_head __rcu **bkt; |
|
unsigned int hash; |
|
void *data; |
|
|
|
new_tbl = rcu_dereference(ht->tbl); |
|
|
|
do { |
|
tbl = new_tbl; |
|
hash = rht_head_hashfn(ht, tbl, obj, ht->p); |
|
if (rcu_access_pointer(tbl->future_tbl)) |
|
/* Failure is OK */ |
|
bkt = rht_bucket_var(tbl, hash); |
|
else |
|
bkt = rht_bucket_insert(ht, tbl, hash); |
|
if (bkt == NULL) { |
|
new_tbl = rht_dereference_rcu(tbl->future_tbl, ht); |
|
data = ERR_PTR(-EAGAIN); |
|
} else { |
|
rht_lock(tbl, bkt); |
|
data = rhashtable_lookup_one(ht, bkt, tbl, |
|
hash, key, obj); |
|
new_tbl = rhashtable_insert_one(ht, bkt, tbl, |
|
hash, obj, data); |
|
if (PTR_ERR(new_tbl) != -EEXIST) |
|
data = ERR_CAST(new_tbl); |
|
|
|
rht_unlock(tbl, bkt); |
|
} |
|
} while (!IS_ERR_OR_NULL(new_tbl)); |
|
|
|
if (PTR_ERR(data) == -EAGAIN) |
|
data = ERR_PTR(rhashtable_insert_rehash(ht, tbl) ?: |
|
-EAGAIN); |
|
|
|
return data; |
|
} |
|
|
|
void *rhashtable_insert_slow(struct rhashtable *ht, const void *key, |
|
struct rhash_head *obj) |
|
{ |
|
void *data; |
|
|
|
do { |
|
rcu_read_lock(); |
|
data = rhashtable_try_insert(ht, key, obj); |
|
rcu_read_unlock(); |
|
} while (PTR_ERR(data) == -EAGAIN); |
|
|
|
return data; |
|
} |
|
EXPORT_SYMBOL_GPL(rhashtable_insert_slow); |
|
|
|
/** |
|
* rhashtable_walk_enter - Initialise an iterator |
|
* @ht: Table to walk over |
|
* @iter: Hash table Iterator |
|
* |
|
* This function prepares a hash table walk. |
|
* |
|
* Note that if you restart a walk after rhashtable_walk_stop you |
|
* may see the same object twice. Also, you may miss objects if |
|
* there are removals in between rhashtable_walk_stop and the next |
|
* call to rhashtable_walk_start. |
|
* |
|
* For a completely stable walk you should construct your own data |
|
* structure outside the hash table. |
|
* |
|
* This function may be called from any process context, including |
|
* non-preemptable context, but cannot be called from softirq or |
|
* hardirq context. |
|
* |
|
* You must call rhashtable_walk_exit after this function returns. |
|
*/ |
|
void rhashtable_walk_enter(struct rhashtable *ht, struct rhashtable_iter *iter) |
|
{ |
|
iter->ht = ht; |
|
iter->p = NULL; |
|
iter->slot = 0; |
|
iter->skip = 0; |
|
iter->end_of_table = 0; |
|
|
|
spin_lock(&ht->lock); |
|
iter->walker.tbl = |
|
rcu_dereference_protected(ht->tbl, lockdep_is_held(&ht->lock)); |
|
list_add(&iter->walker.list, &iter->walker.tbl->walkers); |
|
spin_unlock(&ht->lock); |
|
} |
|
EXPORT_SYMBOL_GPL(rhashtable_walk_enter); |
|
|
|
/** |
|
* rhashtable_walk_exit - Free an iterator |
|
* @iter: Hash table Iterator |
|
* |
|
* This function frees resources allocated by rhashtable_walk_enter. |
|
*/ |
|
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); |
|
} |
|
EXPORT_SYMBOL_GPL(rhashtable_walk_exit); |
|
|
|
/** |
|
* rhashtable_walk_start_check - Start a hash table walk |
|
* @iter: Hash table iterator |
|
* |
|
* Start a hash table walk at the current iterator position. 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 occurred. Note that the iterator |
|
* will rewind back to the beginning and you may use it immediately |
|
* by calling rhashtable_walk_next. |
|
* |
|
* rhashtable_walk_start is defined as an inline variant that returns |
|
* void. This is preferred in cases where the caller would ignore |
|
* resize events and always continue. |
|
*/ |
|
int rhashtable_walk_start_check(struct rhashtable_iter *iter) |
|
__acquires(RCU) |
|
{ |
|
struct rhashtable *ht = iter->ht; |
|
bool rhlist = ht->rhlist; |
|
|
|
rcu_read_lock(); |
|
|
|
spin_lock(&ht->lock); |
|
if (iter->walker.tbl) |
|
list_del(&iter->walker.list); |
|
spin_unlock(&ht->lock); |
|
|
|
if (iter->end_of_table) |
|
return 0; |
|
if (!iter->walker.tbl) { |
|
iter->walker.tbl = rht_dereference_rcu(ht->tbl, ht); |
|
iter->slot = 0; |
|
iter->skip = 0; |
|
return -EAGAIN; |
|
} |
|
|
|
if (iter->p && !rhlist) { |
|
/* |
|
* We need to validate that 'p' is still in the table, and |
|
* if so, update 'skip' |
|
*/ |
|
struct rhash_head *p; |
|
int skip = 0; |
|
rht_for_each_rcu(p, iter->walker.tbl, iter->slot) { |
|
skip++; |
|
if (p == iter->p) { |
|
iter->skip = skip; |
|
goto found; |
|
} |
|
} |
|
iter->p = NULL; |
|
} else if (iter->p && rhlist) { |
|
/* Need to validate that 'list' is still in the table, and |
|
* if so, update 'skip' and 'p'. |
|
*/ |
|
struct rhash_head *p; |
|
struct rhlist_head *list; |
|
int skip = 0; |
|
rht_for_each_rcu(p, iter->walker.tbl, iter->slot) { |
|
for (list = container_of(p, struct rhlist_head, rhead); |
|
list; |
|
list = rcu_dereference(list->next)) { |
|
skip++; |
|
if (list == iter->list) { |
|
iter->p = p; |
|
iter->skip = skip; |
|
goto found; |
|
} |
|
} |
|
} |
|
iter->p = NULL; |
|
} |
|
found: |
|
return 0; |
|
} |
|
EXPORT_SYMBOL_GPL(rhashtable_walk_start_check); |
|
|
|
/** |
|
* __rhashtable_walk_find_next - Find the next element in a table (or the first |
|
* one in case of a new walk). |
|
* |
|
* @iter: Hash table iterator |
|
* |
|
* Returns the found object or NULL when the end of the table is reached. |
|
* |
|
* Returns -EAGAIN if resize event occurred. |
|
*/ |
|
static void *__rhashtable_walk_find_next(struct rhashtable_iter *iter) |
|
{ |
|
struct bucket_table *tbl = iter->walker.tbl; |
|
struct rhlist_head *list = iter->list; |
|
struct rhashtable *ht = iter->ht; |
|
struct rhash_head *p = iter->p; |
|
bool rhlist = ht->rhlist; |
|
|
|
if (!tbl) |
|
return NULL; |
|
|
|
for (; iter->slot < tbl->size; iter->slot++) { |
|
int skip = iter->skip; |
|
|
|
rht_for_each_rcu(p, tbl, iter->slot) { |
|
if (rhlist) { |
|
list = container_of(p, struct rhlist_head, |
|
rhead); |
|
do { |
|
if (!skip) |
|
goto next; |
|
skip--; |
|
list = rcu_dereference(list->next); |
|
} while (list); |
|
|
|
continue; |
|
} |
|
if (!skip) |
|
break; |
|
skip--; |
|
} |
|
|
|
next: |
|
if (!rht_is_a_nulls(p)) { |
|
iter->skip++; |
|
iter->p = p; |
|
iter->list = list; |
|
return rht_obj(ht, rhlist ? &list->rhead : 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); |
|
} else { |
|
iter->end_of_table = true; |
|
} |
|
|
|
return NULL; |
|
} |
|
|
|
/** |
|
* 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 occurred. 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 rhlist_head *list = iter->list; |
|
struct rhashtable *ht = iter->ht; |
|
struct rhash_head *p = iter->p; |
|
bool rhlist = ht->rhlist; |
|
|
|
if (p) { |
|
if (!rhlist || !(list = rcu_dereference(list->next))) { |
|
p = rcu_dereference(p->next); |
|
list = container_of(p, struct rhlist_head, rhead); |
|
} |
|
if (!rht_is_a_nulls(p)) { |
|
iter->skip++; |
|
iter->p = p; |
|
iter->list = list; |
|
return rht_obj(ht, rhlist ? &list->rhead : p); |
|
} |
|
|
|
/* At the end of this slot, switch to next one and then find |
|
* next entry from that point. |
|
*/ |
|
iter->skip = 0; |
|
iter->slot++; |
|
} |
|
|
|
return __rhashtable_walk_find_next(iter); |
|
} |
|
EXPORT_SYMBOL_GPL(rhashtable_walk_next); |
|
|
|
/** |
|
* rhashtable_walk_peek - Return the next object but don't advance the iterator |
|
* @iter: Hash table iterator |
|
* |
|
* Returns the next object or NULL when the end of the table is reached. |
|
* |
|
* Returns -EAGAIN if resize event occurred. Note that the iterator |
|
* will rewind back to the beginning and you may continue to use it. |
|
*/ |
|
void *rhashtable_walk_peek(struct rhashtable_iter *iter) |
|
{ |
|
struct rhlist_head *list = iter->list; |
|
struct rhashtable *ht = iter->ht; |
|
struct rhash_head *p = iter->p; |
|
|
|
if (p) |
|
return rht_obj(ht, ht->rhlist ? &list->rhead : p); |
|
|
|
/* No object found in current iter, find next one in the table. */ |
|
|
|
if (iter->skip) { |
|
/* A nonzero skip value points to the next entry in the table |
|
* beyond that last one that was found. Decrement skip so |
|
* we find the current value. __rhashtable_walk_find_next |
|
* will restore the original value of skip assuming that |
|
* the table hasn't changed. |
|
*/ |
|
iter->skip--; |
|
} |
|
|
|
return __rhashtable_walk_find_next(iter); |
|
} |
|
EXPORT_SYMBOL_GPL(rhashtable_walk_peek); |
|
|
|
/** |
|
* rhashtable_walk_stop - Finish a hash table walk |
|
* @iter: Hash table iterator |
|
* |
|
* Finish a hash table walk. Does not reset the iterator to the start of the |
|
* hash table. |
|
*/ |
|
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 (rcu_head_after_call_rcu(&tbl->rcu, bucket_table_free_rcu)) |
|
/* This bucket table is being freed, don't re-link it. */ |
|
iter->walker.tbl = NULL; |
|
else |
|
list_add(&iter->walker.list, &tbl->walkers); |
|
spin_unlock(&ht->lock); |
|
|
|
out: |
|
rcu_read_unlock(); |
|
} |
|
EXPORT_SYMBOL_GPL(rhashtable_walk_stop); |
|
|
|
static size_t rounded_hashtable_size(const struct rhashtable_params *params) |
|
{ |
|
size_t retsize; |
|
|
|
if (params->nelem_hint) |
|
retsize = max(roundup_pow_of_two(params->nelem_hint * 4 / 3), |
|
(unsigned long)params->min_size); |
|
else |
|
retsize = max(HASH_DEFAULT_SIZE, |
|
(unsigned long)params->min_size); |
|
|
|
return retsize; |
|
} |
|
|
|
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, |
|
* }; |
|
* |
|
* 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; |
|
|
|
if ((!params->key_len && !params->obj_hashfn) || |
|
(params->obj_hashfn && !params->obj_cmpfn)) |
|
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); |
|
|
|
/* Cap total entries at 2^31 to avoid nelems overflow. */ |
|
ht->max_elems = 1u << 31; |
|
|
|
if (params->max_size) { |
|
ht->p.max_size = rounddown_pow_of_two(params->max_size); |
|
if (ht->p.max_size < ht->max_elems / 2) |
|
ht->max_elems = ht->p.max_size * 2; |
|
} |
|
|
|
ht->p.min_size = max_t(u16, ht->p.min_size, HASH_MIN_SIZE); |
|
|
|
size = rounded_hashtable_size(&ht->p); |
|
|
|
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; |
|
} |
|
} |
|
|
|
/* |
|
* This is api initialization and thus we need to guarantee the |
|
* initial rhashtable allocation. Upon failure, retry with the |
|
* smallest possible size with __GFP_NOFAIL semantics. |
|
*/ |
|
tbl = bucket_table_alloc(ht, size, GFP_KERNEL); |
|
if (unlikely(tbl == NULL)) { |
|
size = max_t(u16, ht->p.min_size, HASH_MIN_SIZE); |
|
tbl = bucket_table_alloc(ht, size, GFP_KERNEL | __GFP_NOFAIL); |
|
} |
|
|
|
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); |
|
|
|
/** |
|
* rhltable_init - initialize a new hash list table |
|
* @hlt: hash list table to be initialized |
|
* @params: configuration parameters |
|
* |
|
* Initializes a new hash list table. |
|
* |
|
* See documentation for rhashtable_init. |
|
*/ |
|
int rhltable_init(struct rhltable *hlt, const struct rhashtable_params *params) |
|
{ |
|
int err; |
|
|
|
err = rhashtable_init(&hlt->ht, params); |
|
hlt->ht.rhlist = true; |
|
return err; |
|
} |
|
EXPORT_SYMBOL_GPL(rhltable_init); |
|
|
|
static void rhashtable_free_one(struct rhashtable *ht, struct rhash_head *obj, |
|
void (*free_fn)(void *ptr, void *arg), |
|
void *arg) |
|
{ |
|
struct rhlist_head *list; |
|
|
|
if (!ht->rhlist) { |
|
free_fn(rht_obj(ht, obj), arg); |
|
return; |
|
} |
|
|
|
list = container_of(obj, struct rhlist_head, rhead); |
|
do { |
|
obj = &list->rhead; |
|
list = rht_dereference(list->next, ht); |
|
free_fn(rht_obj(ht, obj), arg); |
|
} while (list); |
|
} |
|
|
|
/** |
|
* 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) |
|
{ |
|
struct bucket_table *tbl, *next_tbl; |
|
unsigned int i; |
|
|
|
cancel_work_sync(&ht->run_work); |
|
|
|
mutex_lock(&ht->mutex); |
|
tbl = rht_dereference(ht->tbl, ht); |
|
restart: |
|
if (free_fn) { |
|
for (i = 0; i < tbl->size; i++) { |
|
struct rhash_head *pos, *next; |
|
|
|
cond_resched(); |
|
for (pos = rht_ptr_exclusive(rht_bucket(tbl, i)), |
|
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) |
|
rhashtable_free_one(ht, pos, free_fn, arg); |
|
} |
|
} |
|
|
|
next_tbl = rht_dereference(tbl->future_tbl, ht); |
|
bucket_table_free(tbl); |
|
if (next_tbl) { |
|
tbl = next_tbl; |
|
goto restart; |
|
} |
|
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); |
|
|
|
struct rhash_lock_head __rcu **__rht_bucket_nested( |
|
const struct bucket_table *tbl, unsigned int hash) |
|
{ |
|
const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *)); |
|
unsigned int index = hash & ((1 << tbl->nest) - 1); |
|
unsigned int size = tbl->size >> tbl->nest; |
|
unsigned int subhash = hash; |
|
union nested_table *ntbl; |
|
|
|
ntbl = nested_table_top(tbl); |
|
ntbl = rht_dereference_bucket_rcu(ntbl[index].table, tbl, hash); |
|
subhash >>= tbl->nest; |
|
|
|
while (ntbl && size > (1 << shift)) { |
|
index = subhash & ((1 << shift) - 1); |
|
ntbl = rht_dereference_bucket_rcu(ntbl[index].table, |
|
tbl, hash); |
|
size >>= shift; |
|
subhash >>= shift; |
|
} |
|
|
|
if (!ntbl) |
|
return NULL; |
|
|
|
return &ntbl[subhash].bucket; |
|
|
|
} |
|
EXPORT_SYMBOL_GPL(__rht_bucket_nested); |
|
|
|
struct rhash_lock_head __rcu **rht_bucket_nested( |
|
const struct bucket_table *tbl, unsigned int hash) |
|
{ |
|
static struct rhash_lock_head __rcu *rhnull; |
|
|
|
if (!rhnull) |
|
INIT_RHT_NULLS_HEAD(rhnull); |
|
return __rht_bucket_nested(tbl, hash) ?: &rhnull; |
|
} |
|
EXPORT_SYMBOL_GPL(rht_bucket_nested); |
|
|
|
struct rhash_lock_head __rcu **rht_bucket_nested_insert( |
|
struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash) |
|
{ |
|
const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *)); |
|
unsigned int index = hash & ((1 << tbl->nest) - 1); |
|
unsigned int size = tbl->size >> tbl->nest; |
|
union nested_table *ntbl; |
|
|
|
ntbl = nested_table_top(tbl); |
|
hash >>= tbl->nest; |
|
ntbl = nested_table_alloc(ht, &ntbl[index].table, |
|
size <= (1 << shift)); |
|
|
|
while (ntbl && size > (1 << shift)) { |
|
index = hash & ((1 << shift) - 1); |
|
size >>= shift; |
|
hash >>= shift; |
|
ntbl = nested_table_alloc(ht, &ntbl[index].table, |
|
size <= (1 << shift)); |
|
} |
|
|
|
if (!ntbl) |
|
return NULL; |
|
|
|
return &ntbl[hash].bucket; |
|
|
|
} |
|
EXPORT_SYMBOL_GPL(rht_bucket_nested_insert);
|
|
|