/*
* Resizable, Scalable, Concurrent Hash Table
*
+ * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
* Copyright (c) 2014-2015 Thomas Graf <tgraf@suug.ch>
* Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net>
*
- * Based on the following paper:
- * https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf
- *
* Code partially derived from nft_hash
+ * Rewritten with rehash code from br_multicast plus single list
+ * pointer as suggested by Josh Triplett
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
#define HASH_MIN_SIZE 4U
#define BUCKET_LOCKS_PER_CPU 128UL
-/* Base bits plus 1 bit for nulls marker */
-#define HASH_RESERVED_SPACE (RHT_BASE_BITS + 1)
-
-/* The bucket lock is selected based on the hash and protects mutations
- * on a group of hash buckets.
- *
- * A maximum of tbl->size/2 bucket locks is allocated. This ensures that
- * a single lock always covers both buckets which may both contains
- * entries which link to the same bucket of the old table during resizing.
- * This allows to simplify the locking as locking the bucket in both
- * tables during resize always guarantee protection.
- *
- * IMPORTANT: When holding the bucket lock of both the old and new table
- * during expansions and shrinking, the old bucket lock must always be
- * acquired first.
- */
-static spinlock_t *bucket_lock(const struct bucket_table *tbl, u32 hash)
-{
- return &tbl->locks[hash & tbl->locks_mask];
-}
-
-static void *rht_obj(const struct rhashtable *ht, const struct rhash_head *he)
-{
- return (void *) he - ht->p.head_offset;
-}
-
-static u32 rht_bucket_index(const struct bucket_table *tbl, u32 hash)
-{
- return (hash >> HASH_RESERVED_SPACE) & (tbl->size - 1);
-}
-
-static u32 key_hashfn(struct rhashtable *ht, const struct bucket_table *tbl,
- const void *key)
-{
- return rht_bucket_index(tbl, ht->p.hashfn(key, ht->p.key_len,
- tbl->hash_rnd));
-}
-
static u32 head_hashfn(struct rhashtable *ht,
const struct bucket_table *tbl,
const struct rhash_head *he)
{
- const char *ptr = rht_obj(ht, he);
-
- return likely(ht->p.key_len) ?
- key_hashfn(ht, tbl, ptr + ht->p.key_offset) :
- rht_bucket_index(tbl, ht->p.obj_hashfn(ptr, tbl->hash_rnd));
+ return rht_head_hashfn(ht, tbl, he, ht->p);
}
#ifdef CONFIG_PROVE_LOCKING
int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash)
{
- spinlock_t *lock = bucket_lock(tbl, hash);
+ spinlock_t *lock = rht_bucket_lock(tbl, hash);
return (debug_locks) ? lockdep_is_held(lock) : 1;
}
return tbl;
}
-/**
- * rht_grow_above_75 - returns true if nelems > 0.75 * table-size
- * @ht: hash table
- * @tbl: current table
- */
-static bool rht_grow_above_75(const struct rhashtable *ht,
- const struct bucket_table *tbl)
-{
- /* Expand table when exceeding 75% load */
- return atomic_read(&ht->nelems) > (tbl->size / 4 * 3) &&
- (!ht->p.max_size || tbl->size < ht->p.max_size);
-}
-
-/**
- * rht_shrink_below_30 - returns true if nelems < 0.3 * table-size
- * @ht: hash table
- * @tbl: current table
- */
-static bool rht_shrink_below_30(const struct rhashtable *ht,
- const struct bucket_table *tbl)
-{
- /* Shrink table beneath 30% load */
- return atomic_read(&ht->nelems) < (tbl->size * 3 / 10) &&
- tbl->size > ht->p.min_size;
-}
-
static int rhashtable_rehash_one(struct rhashtable *ht, unsigned old_hash)
{
struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
new_hash = head_hashfn(ht, new_tbl, entry);
- new_bucket_lock = bucket_lock(new_tbl, new_hash);
+ new_bucket_lock = rht_bucket_lock(new_tbl, new_hash);
spin_lock_nested(new_bucket_lock, SINGLE_DEPTH_NESTING);
head = rht_dereference_bucket(new_tbl->buckets[new_hash],
struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
spinlock_t *old_bucket_lock;
- old_bucket_lock = bucket_lock(old_tbl, old_hash);
+ old_bucket_lock = rht_bucket_lock(old_tbl, old_hash);
spin_lock_bh(old_bucket_lock);
while (!rhashtable_rehash_one(ht, old_hash))
mutex_unlock(&ht->mutex);
}
+int rhashtable_insert_slow(struct rhashtable *ht, const void *key,
+ struct rhash_head *obj,
+ struct bucket_table *tbl)
+{
+ struct rhash_head *head;
+ unsigned hash;
+ int err = -EEXIST;
+
+ hash = head_hashfn(ht, tbl, obj);
+ spin_lock_nested(rht_bucket_lock(tbl, hash), SINGLE_DEPTH_NESTING);
+
+ if (key && rhashtable_lookup_fast(ht, key, ht->p))
+ goto exit;
+
+ err = 0;
+
+ head = rht_dereference_bucket(tbl->buckets[hash], tbl, hash);
+
+ RCU_INIT_POINTER(obj->next, head);
+
+ rcu_assign_pointer(tbl->buckets[hash], obj);
+
+ atomic_inc(&ht->nelems);
+
+exit:
+ spin_unlock(rht_bucket_lock(tbl, hash));
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(rhashtable_insert_slow);
+
static bool __rhashtable_insert(struct rhashtable *ht, struct rhash_head *obj,
bool (*compare)(void *, void *), void *arg)
{
old_tbl = rht_dereference_rcu(ht->tbl, ht);
hash = head_hashfn(ht, old_tbl, obj);
- old_lock = bucket_lock(old_tbl, hash);
+ old_lock = rht_bucket_lock(old_tbl, hash);
spin_lock_bh(old_lock);
tbl = rht_dereference_rcu(old_tbl->future_tbl, ht) ?: old_tbl;
if (tbl != old_tbl) {
hash = head_hashfn(ht, tbl, obj);
- spin_lock_nested(bucket_lock(tbl, hash), SINGLE_DEPTH_NESTING);
+ spin_lock_nested(rht_bucket_lock(tbl, hash),
+ SINGLE_DEPTH_NESTING);
}
if (compare &&
exit:
if (tbl != old_tbl)
- spin_unlock(bucket_lock(tbl, hash));
+ spin_unlock(rht_bucket_lock(tbl, hash));
spin_unlock_bh(old_lock);
bool ret = false;
hash = head_hashfn(ht, tbl, obj);
- lock = bucket_lock(tbl, hash);
+ lock = rht_bucket_lock(tbl, hash);
spin_lock_bh(lock);
}
EXPORT_SYMBOL_GPL(rhashtable_remove);
-struct rhashtable_compare_arg {
- struct rhashtable *ht;
- const void *key;
-};
-
-static bool rhashtable_compare(void *ptr, void *arg)
-{
- struct rhashtable_compare_arg *x = arg;
- struct rhashtable *ht = x->ht;
-
- return !memcmp(ptr + ht->p.key_offset, x->key, ht->p.key_len);
-}
-
/**
* rhashtable_lookup - lookup key in hash table
* @ht: hash table
*/
void *rhashtable_lookup(struct rhashtable *ht, const void *key)
{
- struct rhashtable_compare_arg arg = {
- .ht = ht,
- .key = key,
- };
-
- BUG_ON(!ht->p.key_len);
-
- return rhashtable_lookup_compare(ht, key, &rhashtable_compare, &arg);
+ return rhashtable_lookup_fast(ht, key, ht->p);
}
EXPORT_SYMBOL_GPL(rhashtable_lookup);
* Returns the first entry on which the compare function returned true.
*/
void *rhashtable_lookup_compare(struct rhashtable *ht, const void *key,
- bool (*compare)(void *, void *), void *arg)
+ bool (*compare)(void *, void *),
+ void *arg)
{
const struct bucket_table *tbl;
struct rhash_head *he;
tbl = rht_dereference_rcu(ht->tbl, ht);
restart:
- hash = key_hashfn(ht, tbl, key);
+ hash = rht_key_hashfn(ht, tbl, key, ht->p);
rht_for_each_rcu(he, tbl, hash) {
if (!compare(rht_obj(ht, he), arg))
continue;
*/
bool rhashtable_lookup_insert(struct rhashtable *ht, struct rhash_head *obj)
{
- struct rhashtable_compare_arg arg = {
- .ht = ht,
- .key = rht_obj(ht, obj) + ht->p.key_offset,
- };
-
- BUG_ON(!ht->p.key_len);
-
- return rhashtable_lookup_compare_insert(ht, obj, &rhashtable_compare,
- &arg);
+ return rhashtable_lookup_insert_fast(ht, obj, ht->p);
}
EXPORT_SYMBOL_GPL(rhashtable_lookup_insert);
size = HASH_DEFAULT_SIZE;
- if ((params->key_len && !params->hashfn) ||
- (!params->key_len && !params->obj_hashfn))
+ if ((!(params->key_len && params->hashfn) && !params->obj_hashfn) ||
+ (params->obj_hashfn && !params->obj_cmpfn))
return -EINVAL;
if (params->nulls_base && params->nulls_base < (1U << RHT_BASE_SHIFT))
projects / mirror_ubuntu-zesty-kernel.git / blobdiff