![NeilBrown](/assets/img/avatar_default.png)
Some users of rhashtables might need to move an object from one table to another - this appears to be the reason for the incomplete usage of NULLS markers. To support these, we store a unique NULLS_MARKER at the end of each chain, and when a search fails to find a match, we check if the NULLS marker found was the expected one. If not, the search may not have examined all objects in the target bucket, so it is repeated. The unique NULLS_MARKER is derived from the address of the head of the chain. As this cannot be derived at load-time the static rhnull in rht_bucket_nested() needs to be initialised at run time. Any caller of a lookup function must still be prepared for the possibility that the object returned is in a different table - it might have been there for some time. Note that this does NOT provide support for other uses of NULLS_MARKERs such as allocating with SLAB_TYPESAFE_BY_RCU or changing the key of an object and re-inserting it in the same table. These could only be done safely if new objects were inserted at the *start* of a hash chain, and that is not currently the case. Signed-off-by: NeilBrown <neilb@suse.com> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
1173 lines
35 KiB
C
1173 lines
35 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Resizable, Scalable, Concurrent Hash Table
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*
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* Copyright (c) 2015-2016 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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#ifndef _LINUX_RHASHTABLE_H
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#define _LINUX_RHASHTABLE_H
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#include <linux/err.h>
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#include <linux/errno.h>
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#include <linux/jhash.h>
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#include <linux/list_nulls.h>
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#include <linux/workqueue.h>
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#include <linux/rculist.h>
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#include <linux/rhashtable-types.h>
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/*
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* The end of the chain is marked with a special nulls marks which has
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* the least significant bit set.
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*/
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/* Maximum chain length before rehash
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*
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* The maximum (not average) chain length grows with the size of the hash
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* table, at a rate of (log N)/(log log N).
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*
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* The value of 16 is selected so that even if the hash table grew to
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* 2^32 you would not expect the maximum chain length to exceed it
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* unless we are under attack (or extremely unlucky).
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*
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* As this limit is only to detect attacks, we don't need to set it to a
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* lower value as you'd need the chain length to vastly exceed 16 to have
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* any real effect on the system.
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*/
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#define RHT_ELASTICITY 16u
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/**
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* struct bucket_table - Table of hash buckets
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* @size: Number of hash buckets
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* @nest: Number of bits of first-level nested table.
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* @rehash: Current bucket being rehashed
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* @hash_rnd: Random seed to fold into hash
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* @locks_mask: Mask to apply before accessing locks[]
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* @locks: Array of spinlocks protecting individual buckets
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* @walkers: List of active walkers
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* @rcu: RCU structure for freeing the table
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* @future_tbl: Table under construction during rehashing
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* @ntbl: Nested table used when out of memory.
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* @buckets: size * hash buckets
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*/
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struct bucket_table {
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unsigned int size;
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unsigned int nest;
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unsigned int rehash;
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u32 hash_rnd;
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unsigned int locks_mask;
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spinlock_t *locks;
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struct list_head walkers;
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struct rcu_head rcu;
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struct bucket_table __rcu *future_tbl;
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struct rhash_head __rcu *buckets[] ____cacheline_aligned_in_smp;
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};
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/*
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* NULLS_MARKER() expects a hash value with the low
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* bits mostly likely to be significant, and it discards
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* the msb.
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* We git it an address, in which the bottom 2 bits are
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* always 0, and the msb might be significant.
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* So we shift the address down one bit to align with
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* expectations and avoid losing a significant bit.
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*/
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#define RHT_NULLS_MARKER(ptr) \
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((void *)NULLS_MARKER(((unsigned long) (ptr)) >> 1))
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#define INIT_RHT_NULLS_HEAD(ptr) \
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((ptr) = RHT_NULLS_MARKER(&(ptr)))
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static inline bool rht_is_a_nulls(const struct rhash_head *ptr)
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{
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return ((unsigned long) ptr & 1);
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}
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static inline void *rht_obj(const struct rhashtable *ht,
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const struct rhash_head *he)
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{
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return (char *)he - ht->p.head_offset;
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}
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static inline unsigned int rht_bucket_index(const struct bucket_table *tbl,
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unsigned int hash)
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{
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return hash & (tbl->size - 1);
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}
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static inline unsigned int rht_key_get_hash(struct rhashtable *ht,
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const void *key, const struct rhashtable_params params,
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unsigned int hash_rnd)
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{
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unsigned int hash;
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/* params must be equal to ht->p if it isn't constant. */
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if (!__builtin_constant_p(params.key_len))
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hash = ht->p.hashfn(key, ht->key_len, hash_rnd);
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else if (params.key_len) {
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unsigned int key_len = params.key_len;
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if (params.hashfn)
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hash = params.hashfn(key, key_len, hash_rnd);
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else if (key_len & (sizeof(u32) - 1))
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hash = jhash(key, key_len, hash_rnd);
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else
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hash = jhash2(key, key_len / sizeof(u32), hash_rnd);
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} else {
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unsigned int key_len = ht->p.key_len;
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if (params.hashfn)
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hash = params.hashfn(key, key_len, hash_rnd);
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else
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hash = jhash(key, key_len, hash_rnd);
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}
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return hash;
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}
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static inline unsigned int rht_key_hashfn(
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struct rhashtable *ht, const struct bucket_table *tbl,
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const void *key, const struct rhashtable_params params)
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{
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unsigned int hash = rht_key_get_hash(ht, key, params, tbl->hash_rnd);
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return rht_bucket_index(tbl, hash);
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}
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static inline unsigned int rht_head_hashfn(
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struct rhashtable *ht, const struct bucket_table *tbl,
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const struct rhash_head *he, const struct rhashtable_params params)
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{
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const char *ptr = rht_obj(ht, he);
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return likely(params.obj_hashfn) ?
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rht_bucket_index(tbl, params.obj_hashfn(ptr, params.key_len ?:
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ht->p.key_len,
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tbl->hash_rnd)) :
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rht_key_hashfn(ht, tbl, ptr + params.key_offset, params);
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}
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/**
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* rht_grow_above_75 - returns true if nelems > 0.75 * table-size
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* @ht: hash table
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* @tbl: current table
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*/
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static inline bool rht_grow_above_75(const struct rhashtable *ht,
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const struct bucket_table *tbl)
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{
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/* Expand table when exceeding 75% load */
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return atomic_read(&ht->nelems) > (tbl->size / 4 * 3) &&
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(!ht->p.max_size || tbl->size < ht->p.max_size);
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}
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/**
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* rht_shrink_below_30 - returns true if nelems < 0.3 * table-size
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* @ht: hash table
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* @tbl: current table
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*/
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static inline bool rht_shrink_below_30(const struct rhashtable *ht,
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const struct bucket_table *tbl)
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{
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/* Shrink table beneath 30% load */
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return atomic_read(&ht->nelems) < (tbl->size * 3 / 10) &&
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tbl->size > ht->p.min_size;
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}
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/**
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* rht_grow_above_100 - returns true if nelems > table-size
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* @ht: hash table
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* @tbl: current table
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*/
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static inline bool rht_grow_above_100(const struct rhashtable *ht,
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const struct bucket_table *tbl)
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{
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return atomic_read(&ht->nelems) > tbl->size &&
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(!ht->p.max_size || tbl->size < ht->p.max_size);
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}
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/**
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* rht_grow_above_max - returns true if table is above maximum
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* @ht: hash table
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* @tbl: current table
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*/
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static inline bool rht_grow_above_max(const struct rhashtable *ht,
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const struct bucket_table *tbl)
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{
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return atomic_read(&ht->nelems) >= ht->max_elems;
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}
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/* The bucket lock is selected based on the hash and protects mutations
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* on a group of hash buckets.
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*
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* A maximum of tbl->size/2 bucket locks is allocated. This ensures that
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* a single lock always covers both buckets which may both contains
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* entries which link to the same bucket of the old table during resizing.
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* This allows to simplify the locking as locking the bucket in both
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* tables during resize always guarantee protection.
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*
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* IMPORTANT: When holding the bucket lock of both the old and new table
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* during expansions and shrinking, the old bucket lock must always be
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* acquired first.
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*/
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static inline spinlock_t *rht_bucket_lock(const struct bucket_table *tbl,
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unsigned int hash)
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{
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return &tbl->locks[hash & tbl->locks_mask];
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}
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#ifdef CONFIG_PROVE_LOCKING
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int lockdep_rht_mutex_is_held(struct rhashtable *ht);
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int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash);
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#else
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static inline int lockdep_rht_mutex_is_held(struct rhashtable *ht)
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{
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return 1;
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}
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static inline int lockdep_rht_bucket_is_held(const struct bucket_table *tbl,
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u32 hash)
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{
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return 1;
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}
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#endif /* CONFIG_PROVE_LOCKING */
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void *rhashtable_insert_slow(struct rhashtable *ht, const void *key,
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struct rhash_head *obj);
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void rhashtable_walk_enter(struct rhashtable *ht,
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struct rhashtable_iter *iter);
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void rhashtable_walk_exit(struct rhashtable_iter *iter);
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int rhashtable_walk_start_check(struct rhashtable_iter *iter) __acquires(RCU);
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static inline void rhashtable_walk_start(struct rhashtable_iter *iter)
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{
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(void)rhashtable_walk_start_check(iter);
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}
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void *rhashtable_walk_next(struct rhashtable_iter *iter);
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void *rhashtable_walk_peek(struct rhashtable_iter *iter);
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void rhashtable_walk_stop(struct rhashtable_iter *iter) __releases(RCU);
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void rhashtable_free_and_destroy(struct rhashtable *ht,
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void (*free_fn)(void *ptr, void *arg),
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void *arg);
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void rhashtable_destroy(struct rhashtable *ht);
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struct rhash_head __rcu **rht_bucket_nested(const struct bucket_table *tbl,
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unsigned int hash);
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struct rhash_head __rcu **rht_bucket_nested_insert(struct rhashtable *ht,
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struct bucket_table *tbl,
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unsigned int hash);
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#define rht_dereference(p, ht) \
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rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht))
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#define rht_dereference_rcu(p, ht) \
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rcu_dereference_check(p, lockdep_rht_mutex_is_held(ht))
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#define rht_dereference_bucket(p, tbl, hash) \
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rcu_dereference_protected(p, lockdep_rht_bucket_is_held(tbl, hash))
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#define rht_dereference_bucket_rcu(p, tbl, hash) \
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rcu_dereference_check(p, lockdep_rht_bucket_is_held(tbl, hash))
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#define rht_entry(tpos, pos, member) \
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({ tpos = container_of(pos, typeof(*tpos), member); 1; })
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static inline struct rhash_head __rcu *const *rht_bucket(
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const struct bucket_table *tbl, unsigned int hash)
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{
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return unlikely(tbl->nest) ? rht_bucket_nested(tbl, hash) :
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&tbl->buckets[hash];
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}
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static inline struct rhash_head __rcu **rht_bucket_var(
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struct bucket_table *tbl, unsigned int hash)
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{
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return unlikely(tbl->nest) ? rht_bucket_nested(tbl, hash) :
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&tbl->buckets[hash];
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}
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static inline struct rhash_head __rcu **rht_bucket_insert(
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struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash)
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{
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return unlikely(tbl->nest) ? rht_bucket_nested_insert(ht, tbl, hash) :
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&tbl->buckets[hash];
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}
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/**
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* rht_for_each_continue - continue iterating over hash chain
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* @pos: the &struct rhash_head to use as a loop cursor.
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* @head: the previous &struct rhash_head to continue from
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* @tbl: the &struct bucket_table
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* @hash: the hash value / bucket index
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*/
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#define rht_for_each_continue(pos, head, tbl, hash) \
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for (pos = rht_dereference_bucket(head, tbl, hash); \
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!rht_is_a_nulls(pos); \
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pos = rht_dereference_bucket((pos)->next, tbl, hash))
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/**
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* rht_for_each - iterate over hash chain
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* @pos: the &struct rhash_head to use as a loop cursor.
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* @tbl: the &struct bucket_table
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* @hash: the hash value / bucket index
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*/
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#define rht_for_each(pos, tbl, hash) \
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rht_for_each_continue(pos, *rht_bucket(tbl, hash), tbl, hash)
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/**
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* rht_for_each_entry_continue - continue iterating over hash chain
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* @tpos: the type * to use as a loop cursor.
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* @pos: the &struct rhash_head to use as a loop cursor.
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* @head: the previous &struct rhash_head to continue from
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* @tbl: the &struct bucket_table
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* @hash: the hash value / bucket index
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* @member: name of the &struct rhash_head within the hashable struct.
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*/
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#define rht_for_each_entry_continue(tpos, pos, head, tbl, hash, member) \
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for (pos = rht_dereference_bucket(head, tbl, hash); \
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(!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
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pos = rht_dereference_bucket((pos)->next, tbl, hash))
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/**
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* rht_for_each_entry - iterate over hash chain of given type
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* @tpos: the type * to use as a loop cursor.
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* @pos: the &struct rhash_head to use as a loop cursor.
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* @tbl: the &struct bucket_table
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* @hash: the hash value / bucket index
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* @member: name of the &struct rhash_head within the hashable struct.
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*/
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#define rht_for_each_entry(tpos, pos, tbl, hash, member) \
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rht_for_each_entry_continue(tpos, pos, *rht_bucket(tbl, hash), \
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tbl, hash, member)
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/**
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* rht_for_each_entry_safe - safely iterate over hash chain of given type
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* @tpos: the type * to use as a loop cursor.
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* @pos: the &struct rhash_head to use as a loop cursor.
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* @next: the &struct rhash_head to use as next in loop cursor.
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* @tbl: the &struct bucket_table
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* @hash: the hash value / bucket index
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* @member: name of the &struct rhash_head within the hashable struct.
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*
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* This hash chain list-traversal primitive allows for the looped code to
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* remove the loop cursor from the list.
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*/
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#define rht_for_each_entry_safe(tpos, pos, next, tbl, hash, member) \
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for (pos = rht_dereference_bucket(*rht_bucket(tbl, hash), tbl, hash), \
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next = !rht_is_a_nulls(pos) ? \
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rht_dereference_bucket(pos->next, tbl, hash) : NULL; \
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(!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
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pos = next, \
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next = !rht_is_a_nulls(pos) ? \
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rht_dereference_bucket(pos->next, tbl, hash) : NULL)
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/**
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* rht_for_each_rcu_continue - continue iterating over rcu hash chain
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* @pos: the &struct rhash_head to use as a loop cursor.
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* @head: the previous &struct rhash_head to continue from
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* @tbl: the &struct bucket_table
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* @hash: the hash value / bucket index
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*
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* This hash chain list-traversal primitive may safely run concurrently with
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* the _rcu mutation primitives such as rhashtable_insert() as long as the
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* traversal is guarded by rcu_read_lock().
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*/
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#define rht_for_each_rcu_continue(pos, head, tbl, hash) \
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for (({barrier(); }), \
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pos = rht_dereference_bucket_rcu(head, tbl, hash); \
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!rht_is_a_nulls(pos); \
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pos = rcu_dereference_raw(pos->next))
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/**
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* rht_for_each_rcu - iterate over rcu hash chain
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* @pos: the &struct rhash_head to use as a loop cursor.
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* @tbl: the &struct bucket_table
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* @hash: the hash value / bucket index
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*
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* This hash chain list-traversal primitive may safely run concurrently with
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* the _rcu mutation primitives such as rhashtable_insert() as long as the
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* traversal is guarded by rcu_read_lock().
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*/
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#define rht_for_each_rcu(pos, tbl, hash) \
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rht_for_each_rcu_continue(pos, *rht_bucket(tbl, hash), tbl, hash)
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/**
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* rht_for_each_entry_rcu_continue - continue iterating over rcu hash chain
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* @tpos: the type * to use as a loop cursor.
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* @pos: the &struct rhash_head to use as a loop cursor.
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* @head: the previous &struct rhash_head to continue from
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* @tbl: the &struct bucket_table
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* @hash: the hash value / bucket index
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* @member: name of the &struct rhash_head within the hashable struct.
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*
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* This hash chain list-traversal primitive may safely run concurrently with
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* the _rcu mutation primitives such as rhashtable_insert() as long as the
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* traversal is guarded by rcu_read_lock().
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*/
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#define rht_for_each_entry_rcu_continue(tpos, pos, head, tbl, hash, member) \
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for (({barrier(); }), \
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pos = rht_dereference_bucket_rcu(head, tbl, hash); \
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(!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
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pos = rht_dereference_bucket_rcu(pos->next, tbl, hash))
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/**
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* rht_for_each_entry_rcu - iterate over rcu hash chain of given type
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* @tpos: the type * to use as a loop cursor.
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* @pos: the &struct rhash_head to use as a loop cursor.
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* @tbl: the &struct bucket_table
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* @hash: the hash value / bucket index
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* @member: name of the &struct rhash_head within the hashable struct.
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*
|
|
* This hash chain list-traversal primitive may safely run concurrently with
|
|
* the _rcu mutation primitives such as rhashtable_insert() as long as the
|
|
* traversal is guarded by rcu_read_lock().
|
|
*/
|
|
#define rht_for_each_entry_rcu(tpos, pos, tbl, hash, member) \
|
|
rht_for_each_entry_rcu_continue(tpos, pos, *rht_bucket(tbl, hash), \
|
|
tbl, hash, member)
|
|
|
|
/**
|
|
* rhl_for_each_rcu - iterate over rcu hash table list
|
|
* @pos: the &struct rlist_head to use as a loop cursor.
|
|
* @list: the head of the list
|
|
*
|
|
* This hash chain list-traversal primitive should be used on the
|
|
* list returned by rhltable_lookup.
|
|
*/
|
|
#define rhl_for_each_rcu(pos, list) \
|
|
for (pos = list; pos; pos = rcu_dereference_raw(pos->next))
|
|
|
|
/**
|
|
* rhl_for_each_entry_rcu - iterate over rcu hash table list of given type
|
|
* @tpos: the type * to use as a loop cursor.
|
|
* @pos: the &struct rlist_head to use as a loop cursor.
|
|
* @list: the head of the list
|
|
* @member: name of the &struct rlist_head within the hashable struct.
|
|
*
|
|
* This hash chain list-traversal primitive should be used on the
|
|
* list returned by rhltable_lookup.
|
|
*/
|
|
#define rhl_for_each_entry_rcu(tpos, pos, list, member) \
|
|
for (pos = list; pos && rht_entry(tpos, pos, member); \
|
|
pos = rcu_dereference_raw(pos->next))
|
|
|
|
static inline int rhashtable_compare(struct rhashtable_compare_arg *arg,
|
|
const void *obj)
|
|
{
|
|
struct rhashtable *ht = arg->ht;
|
|
const char *ptr = obj;
|
|
|
|
return memcmp(ptr + ht->p.key_offset, arg->key, ht->p.key_len);
|
|
}
|
|
|
|
/* Internal function, do not use. */
|
|
static inline struct rhash_head *__rhashtable_lookup(
|
|
struct rhashtable *ht, const void *key,
|
|
const struct rhashtable_params params)
|
|
{
|
|
struct rhashtable_compare_arg arg = {
|
|
.ht = ht,
|
|
.key = key,
|
|
};
|
|
struct rhash_head __rcu * const *head;
|
|
struct bucket_table *tbl;
|
|
struct rhash_head *he;
|
|
unsigned int hash;
|
|
|
|
tbl = rht_dereference_rcu(ht->tbl, ht);
|
|
restart:
|
|
hash = rht_key_hashfn(ht, tbl, key, params);
|
|
head = rht_bucket(tbl, hash);
|
|
do {
|
|
rht_for_each_rcu_continue(he, *head, tbl, hash) {
|
|
if (params.obj_cmpfn ?
|
|
params.obj_cmpfn(&arg, rht_obj(ht, he)) :
|
|
rhashtable_compare(&arg, rht_obj(ht, he)))
|
|
continue;
|
|
return he;
|
|
}
|
|
/* An object might have been moved to a different hash chain,
|
|
* while we walk along it - better check and retry.
|
|
*/
|
|
} while (he != RHT_NULLS_MARKER(head));
|
|
|
|
/* Ensure we see any new tables. */
|
|
smp_rmb();
|
|
|
|
tbl = rht_dereference_rcu(tbl->future_tbl, ht);
|
|
if (unlikely(tbl))
|
|
goto restart;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* rhashtable_lookup - search hash table
|
|
* @ht: hash table
|
|
* @key: the pointer to the key
|
|
* @params: hash table parameters
|
|
*
|
|
* Computes the hash value for the key and traverses the bucket chain looking
|
|
* for a entry with an identical key. The first matching entry is returned.
|
|
*
|
|
* This must only be called under the RCU read lock.
|
|
*
|
|
* Returns the first entry on which the compare function returned true.
|
|
*/
|
|
static inline void *rhashtable_lookup(
|
|
struct rhashtable *ht, const void *key,
|
|
const struct rhashtable_params params)
|
|
{
|
|
struct rhash_head *he = __rhashtable_lookup(ht, key, params);
|
|
|
|
return he ? rht_obj(ht, he) : NULL;
|
|
}
|
|
|
|
/**
|
|
* rhashtable_lookup_fast - search hash table, without RCU read lock
|
|
* @ht: hash table
|
|
* @key: the pointer to the key
|
|
* @params: hash table parameters
|
|
*
|
|
* Computes the hash value for the key and traverses the bucket chain looking
|
|
* for a entry with an identical key. The first matching entry is returned.
|
|
*
|
|
* Only use this function when you have other mechanisms guaranteeing
|
|
* that the object won't go away after the RCU read lock is released.
|
|
*
|
|
* Returns the first entry on which the compare function returned true.
|
|
*/
|
|
static inline void *rhashtable_lookup_fast(
|
|
struct rhashtable *ht, const void *key,
|
|
const struct rhashtable_params params)
|
|
{
|
|
void *obj;
|
|
|
|
rcu_read_lock();
|
|
obj = rhashtable_lookup(ht, key, params);
|
|
rcu_read_unlock();
|
|
|
|
return obj;
|
|
}
|
|
|
|
/**
|
|
* rhltable_lookup - search hash list table
|
|
* @hlt: hash table
|
|
* @key: the pointer to the key
|
|
* @params: hash table parameters
|
|
*
|
|
* Computes the hash value for the key and traverses the bucket chain looking
|
|
* for a entry with an identical key. All matching entries are returned
|
|
* in a list.
|
|
*
|
|
* This must only be called under the RCU read lock.
|
|
*
|
|
* Returns the list of entries that match the given key.
|
|
*/
|
|
static inline struct rhlist_head *rhltable_lookup(
|
|
struct rhltable *hlt, const void *key,
|
|
const struct rhashtable_params params)
|
|
{
|
|
struct rhash_head *he = __rhashtable_lookup(&hlt->ht, key, params);
|
|
|
|
return he ? container_of(he, struct rhlist_head, rhead) : NULL;
|
|
}
|
|
|
|
/* Internal function, please use rhashtable_insert_fast() instead. This
|
|
* function returns the existing element already in hashes in there is a clash,
|
|
* otherwise it returns an error via ERR_PTR().
|
|
*/
|
|
static inline void *__rhashtable_insert_fast(
|
|
struct rhashtable *ht, const void *key, struct rhash_head *obj,
|
|
const struct rhashtable_params params, bool rhlist)
|
|
{
|
|
struct rhashtable_compare_arg arg = {
|
|
.ht = ht,
|
|
.key = key,
|
|
};
|
|
struct rhash_head __rcu **pprev;
|
|
struct bucket_table *tbl;
|
|
struct rhash_head *head;
|
|
spinlock_t *lock;
|
|
unsigned int hash;
|
|
int elasticity;
|
|
void *data;
|
|
|
|
rcu_read_lock();
|
|
|
|
tbl = rht_dereference_rcu(ht->tbl, ht);
|
|
hash = rht_head_hashfn(ht, tbl, obj, params);
|
|
lock = rht_bucket_lock(tbl, hash);
|
|
spin_lock_bh(lock);
|
|
|
|
if (unlikely(rcu_access_pointer(tbl->future_tbl))) {
|
|
slow_path:
|
|
spin_unlock_bh(lock);
|
|
rcu_read_unlock();
|
|
return rhashtable_insert_slow(ht, key, obj);
|
|
}
|
|
|
|
elasticity = RHT_ELASTICITY;
|
|
pprev = rht_bucket_insert(ht, tbl, hash);
|
|
data = ERR_PTR(-ENOMEM);
|
|
if (!pprev)
|
|
goto out;
|
|
|
|
rht_for_each_continue(head, *pprev, tbl, hash) {
|
|
struct rhlist_head *plist;
|
|
struct rhlist_head *list;
|
|
|
|
elasticity--;
|
|
if (!key ||
|
|
(params.obj_cmpfn ?
|
|
params.obj_cmpfn(&arg, rht_obj(ht, head)) :
|
|
rhashtable_compare(&arg, rht_obj(ht, head)))) {
|
|
pprev = &head->next;
|
|
continue;
|
|
}
|
|
|
|
data = rht_obj(ht, head);
|
|
|
|
if (!rhlist)
|
|
goto out;
|
|
|
|
|
|
list = container_of(obj, struct rhlist_head, rhead);
|
|
plist = container_of(head, struct rhlist_head, rhead);
|
|
|
|
RCU_INIT_POINTER(list->next, plist);
|
|
head = rht_dereference_bucket(head->next, tbl, hash);
|
|
RCU_INIT_POINTER(list->rhead.next, head);
|
|
rcu_assign_pointer(*pprev, obj);
|
|
|
|
goto good;
|
|
}
|
|
|
|
if (elasticity <= 0)
|
|
goto slow_path;
|
|
|
|
data = ERR_PTR(-E2BIG);
|
|
if (unlikely(rht_grow_above_max(ht, tbl)))
|
|
goto out;
|
|
|
|
if (unlikely(rht_grow_above_100(ht, tbl)))
|
|
goto slow_path;
|
|
|
|
head = rht_dereference_bucket(*pprev, tbl, hash);
|
|
|
|
RCU_INIT_POINTER(obj->next, head);
|
|
if (rhlist) {
|
|
struct rhlist_head *list;
|
|
|
|
list = container_of(obj, struct rhlist_head, rhead);
|
|
RCU_INIT_POINTER(list->next, NULL);
|
|
}
|
|
|
|
rcu_assign_pointer(*pprev, obj);
|
|
|
|
atomic_inc(&ht->nelems);
|
|
if (rht_grow_above_75(ht, tbl))
|
|
schedule_work(&ht->run_work);
|
|
|
|
good:
|
|
data = NULL;
|
|
|
|
out:
|
|
spin_unlock_bh(lock);
|
|
rcu_read_unlock();
|
|
|
|
return data;
|
|
}
|
|
|
|
/**
|
|
* rhashtable_insert_fast - insert object into hash table
|
|
* @ht: hash table
|
|
* @obj: pointer to hash head inside object
|
|
* @params: hash table parameters
|
|
*
|
|
* Will take a per bucket spinlock to protect against mutual mutations
|
|
* on the same bucket. Multiple insertions may occur in parallel unless
|
|
* they map to the same bucket lock.
|
|
*
|
|
* It is safe to call this function from atomic context.
|
|
*
|
|
* Will trigger an automatic deferred table resizing if residency in the
|
|
* table grows beyond 70%.
|
|
*/
|
|
static inline int rhashtable_insert_fast(
|
|
struct rhashtable *ht, struct rhash_head *obj,
|
|
const struct rhashtable_params params)
|
|
{
|
|
void *ret;
|
|
|
|
ret = __rhashtable_insert_fast(ht, NULL, obj, params, false);
|
|
if (IS_ERR(ret))
|
|
return PTR_ERR(ret);
|
|
|
|
return ret == NULL ? 0 : -EEXIST;
|
|
}
|
|
|
|
/**
|
|
* rhltable_insert_key - insert object into hash list table
|
|
* @hlt: hash list table
|
|
* @key: the pointer to the key
|
|
* @list: pointer to hash list head inside object
|
|
* @params: hash table parameters
|
|
*
|
|
* Will take a per bucket spinlock to protect against mutual mutations
|
|
* on the same bucket. Multiple insertions may occur in parallel unless
|
|
* they map to the same bucket lock.
|
|
*
|
|
* It is safe to call this function from atomic context.
|
|
*
|
|
* Will trigger an automatic deferred table resizing if residency in the
|
|
* table grows beyond 70%.
|
|
*/
|
|
static inline int rhltable_insert_key(
|
|
struct rhltable *hlt, const void *key, struct rhlist_head *list,
|
|
const struct rhashtable_params params)
|
|
{
|
|
return PTR_ERR(__rhashtable_insert_fast(&hlt->ht, key, &list->rhead,
|
|
params, true));
|
|
}
|
|
|
|
/**
|
|
* rhltable_insert - insert object into hash list table
|
|
* @hlt: hash list table
|
|
* @list: pointer to hash list head inside object
|
|
* @params: hash table parameters
|
|
*
|
|
* Will take a per bucket spinlock to protect against mutual mutations
|
|
* on the same bucket. Multiple insertions may occur in parallel unless
|
|
* they map to the same bucket lock.
|
|
*
|
|
* It is safe to call this function from atomic context.
|
|
*
|
|
* Will trigger an automatic deferred table resizing if residency in the
|
|
* table grows beyond 70%.
|
|
*/
|
|
static inline int rhltable_insert(
|
|
struct rhltable *hlt, struct rhlist_head *list,
|
|
const struct rhashtable_params params)
|
|
{
|
|
const char *key = rht_obj(&hlt->ht, &list->rhead);
|
|
|
|
key += params.key_offset;
|
|
|
|
return rhltable_insert_key(hlt, key, list, params);
|
|
}
|
|
|
|
/**
|
|
* rhashtable_lookup_insert_fast - lookup and insert object into hash table
|
|
* @ht: hash table
|
|
* @obj: pointer to hash head inside object
|
|
* @params: hash table parameters
|
|
*
|
|
* Locks down the bucket chain in both the old and new table if a resize
|
|
* is in progress to ensure that writers can't remove from the old table
|
|
* and can't insert to the new table during the atomic operation of search
|
|
* and insertion. Searches for duplicates in both the old and new table if
|
|
* a resize is in progress.
|
|
*
|
|
* This lookup function may only be used for fixed key hash table (key_len
|
|
* parameter set). It will BUG() if used inappropriately.
|
|
*
|
|
* It is safe to call this function from atomic context.
|
|
*
|
|
* Will trigger an automatic deferred table resizing if residency in the
|
|
* table grows beyond 70%.
|
|
*/
|
|
static inline int rhashtable_lookup_insert_fast(
|
|
struct rhashtable *ht, struct rhash_head *obj,
|
|
const struct rhashtable_params params)
|
|
{
|
|
const char *key = rht_obj(ht, obj);
|
|
void *ret;
|
|
|
|
BUG_ON(ht->p.obj_hashfn);
|
|
|
|
ret = __rhashtable_insert_fast(ht, key + ht->p.key_offset, obj, params,
|
|
false);
|
|
if (IS_ERR(ret))
|
|
return PTR_ERR(ret);
|
|
|
|
return ret == NULL ? 0 : -EEXIST;
|
|
}
|
|
|
|
/**
|
|
* rhashtable_lookup_get_insert_fast - lookup and insert object into hash table
|
|
* @ht: hash table
|
|
* @obj: pointer to hash head inside object
|
|
* @params: hash table parameters
|
|
*
|
|
* Just like rhashtable_lookup_insert_fast(), but this function returns the
|
|
* object if it exists, NULL if it did not and the insertion was successful,
|
|
* and an ERR_PTR otherwise.
|
|
*/
|
|
static inline void *rhashtable_lookup_get_insert_fast(
|
|
struct rhashtable *ht, struct rhash_head *obj,
|
|
const struct rhashtable_params params)
|
|
{
|
|
const char *key = rht_obj(ht, obj);
|
|
|
|
BUG_ON(ht->p.obj_hashfn);
|
|
|
|
return __rhashtable_insert_fast(ht, key + ht->p.key_offset, obj, params,
|
|
false);
|
|
}
|
|
|
|
/**
|
|
* rhashtable_lookup_insert_key - search and insert object to hash table
|
|
* with explicit key
|
|
* @ht: hash table
|
|
* @key: key
|
|
* @obj: pointer to hash head inside object
|
|
* @params: hash table parameters
|
|
*
|
|
* Locks down the bucket chain in both the old and new table if a resize
|
|
* is in progress to ensure that writers can't remove from the old table
|
|
* and can't insert to the new table during the atomic operation of search
|
|
* and insertion. Searches for duplicates in both the old and new table if
|
|
* a resize is in progress.
|
|
*
|
|
* Lookups may occur in parallel with hashtable mutations and resizing.
|
|
*
|
|
* Will trigger an automatic deferred table resizing if residency in the
|
|
* table grows beyond 70%.
|
|
*
|
|
* Returns zero on success.
|
|
*/
|
|
static inline int rhashtable_lookup_insert_key(
|
|
struct rhashtable *ht, const void *key, struct rhash_head *obj,
|
|
const struct rhashtable_params params)
|
|
{
|
|
void *ret;
|
|
|
|
BUG_ON(!ht->p.obj_hashfn || !key);
|
|
|
|
ret = __rhashtable_insert_fast(ht, key, obj, params, false);
|
|
if (IS_ERR(ret))
|
|
return PTR_ERR(ret);
|
|
|
|
return ret == NULL ? 0 : -EEXIST;
|
|
}
|
|
|
|
/**
|
|
* rhashtable_lookup_get_insert_key - lookup and insert object into hash table
|
|
* @ht: hash table
|
|
* @obj: pointer to hash head inside object
|
|
* @params: hash table parameters
|
|
* @data: pointer to element data already in hashes
|
|
*
|
|
* Just like rhashtable_lookup_insert_key(), but this function returns the
|
|
* object if it exists, NULL if it does not and the insertion was successful,
|
|
* and an ERR_PTR otherwise.
|
|
*/
|
|
static inline void *rhashtable_lookup_get_insert_key(
|
|
struct rhashtable *ht, const void *key, struct rhash_head *obj,
|
|
const struct rhashtable_params params)
|
|
{
|
|
BUG_ON(!ht->p.obj_hashfn || !key);
|
|
|
|
return __rhashtable_insert_fast(ht, key, obj, params, false);
|
|
}
|
|
|
|
/* Internal function, please use rhashtable_remove_fast() instead */
|
|
static inline int __rhashtable_remove_fast_one(
|
|
struct rhashtable *ht, struct bucket_table *tbl,
|
|
struct rhash_head *obj, const struct rhashtable_params params,
|
|
bool rhlist)
|
|
{
|
|
struct rhash_head __rcu **pprev;
|
|
struct rhash_head *he;
|
|
spinlock_t * lock;
|
|
unsigned int hash;
|
|
int err = -ENOENT;
|
|
|
|
hash = rht_head_hashfn(ht, tbl, obj, params);
|
|
lock = rht_bucket_lock(tbl, hash);
|
|
|
|
spin_lock_bh(lock);
|
|
|
|
pprev = rht_bucket_var(tbl, hash);
|
|
rht_for_each_continue(he, *pprev, tbl, hash) {
|
|
struct rhlist_head *list;
|
|
|
|
list = container_of(he, struct rhlist_head, rhead);
|
|
|
|
if (he != obj) {
|
|
struct rhlist_head __rcu **lpprev;
|
|
|
|
pprev = &he->next;
|
|
|
|
if (!rhlist)
|
|
continue;
|
|
|
|
do {
|
|
lpprev = &list->next;
|
|
list = rht_dereference_bucket(list->next,
|
|
tbl, hash);
|
|
} while (list && obj != &list->rhead);
|
|
|
|
if (!list)
|
|
continue;
|
|
|
|
list = rht_dereference_bucket(list->next, tbl, hash);
|
|
RCU_INIT_POINTER(*lpprev, list);
|
|
err = 0;
|
|
break;
|
|
}
|
|
|
|
obj = rht_dereference_bucket(obj->next, tbl, hash);
|
|
err = 1;
|
|
|
|
if (rhlist) {
|
|
list = rht_dereference_bucket(list->next, tbl, hash);
|
|
if (list) {
|
|
RCU_INIT_POINTER(list->rhead.next, obj);
|
|
obj = &list->rhead;
|
|
err = 0;
|
|
}
|
|
}
|
|
|
|
rcu_assign_pointer(*pprev, obj);
|
|
break;
|
|
}
|
|
|
|
spin_unlock_bh(lock);
|
|
|
|
if (err > 0) {
|
|
atomic_dec(&ht->nelems);
|
|
if (unlikely(ht->p.automatic_shrinking &&
|
|
rht_shrink_below_30(ht, tbl)))
|
|
schedule_work(&ht->run_work);
|
|
err = 0;
|
|
}
|
|
|
|
return err;
|
|
}
|
|
|
|
/* Internal function, please use rhashtable_remove_fast() instead */
|
|
static inline int __rhashtable_remove_fast(
|
|
struct rhashtable *ht, struct rhash_head *obj,
|
|
const struct rhashtable_params params, bool rhlist)
|
|
{
|
|
struct bucket_table *tbl;
|
|
int err;
|
|
|
|
rcu_read_lock();
|
|
|
|
tbl = rht_dereference_rcu(ht->tbl, ht);
|
|
|
|
/* Because we have already taken (and released) the bucket
|
|
* lock in old_tbl, if we find that future_tbl is not yet
|
|
* visible then that guarantees the entry to still be in
|
|
* the old tbl if it exists.
|
|
*/
|
|
while ((err = __rhashtable_remove_fast_one(ht, tbl, obj, params,
|
|
rhlist)) &&
|
|
(tbl = rht_dereference_rcu(tbl->future_tbl, ht)))
|
|
;
|
|
|
|
rcu_read_unlock();
|
|
|
|
return err;
|
|
}
|
|
|
|
/**
|
|
* rhashtable_remove_fast - remove object from hash table
|
|
* @ht: hash table
|
|
* @obj: pointer to hash head inside object
|
|
* @params: hash table parameters
|
|
*
|
|
* Since the hash chain is single linked, the removal operation needs to
|
|
* walk the bucket chain upon removal. The removal operation is thus
|
|
* considerable slow if the hash table is not correctly sized.
|
|
*
|
|
* Will automatically shrink the table if permitted when residency drops
|
|
* below 30%.
|
|
*
|
|
* Returns zero on success, -ENOENT if the entry could not be found.
|
|
*/
|
|
static inline int rhashtable_remove_fast(
|
|
struct rhashtable *ht, struct rhash_head *obj,
|
|
const struct rhashtable_params params)
|
|
{
|
|
return __rhashtable_remove_fast(ht, obj, params, false);
|
|
}
|
|
|
|
/**
|
|
* rhltable_remove - remove object from hash list table
|
|
* @hlt: hash list table
|
|
* @list: pointer to hash list head inside object
|
|
* @params: hash table parameters
|
|
*
|
|
* Since the hash chain is single linked, the removal operation needs to
|
|
* walk the bucket chain upon removal. The removal operation is thus
|
|
* considerable slow if the hash table is not correctly sized.
|
|
*
|
|
* Will automatically shrink the table if permitted when residency drops
|
|
* below 30%
|
|
*
|
|
* Returns zero on success, -ENOENT if the entry could not be found.
|
|
*/
|
|
static inline int rhltable_remove(
|
|
struct rhltable *hlt, struct rhlist_head *list,
|
|
const struct rhashtable_params params)
|
|
{
|
|
return __rhashtable_remove_fast(&hlt->ht, &list->rhead, params, true);
|
|
}
|
|
|
|
/* Internal function, please use rhashtable_replace_fast() instead */
|
|
static inline int __rhashtable_replace_fast(
|
|
struct rhashtable *ht, struct bucket_table *tbl,
|
|
struct rhash_head *obj_old, struct rhash_head *obj_new,
|
|
const struct rhashtable_params params)
|
|
{
|
|
struct rhash_head __rcu **pprev;
|
|
struct rhash_head *he;
|
|
spinlock_t *lock;
|
|
unsigned int hash;
|
|
int err = -ENOENT;
|
|
|
|
/* Minimally, the old and new objects must have same hash
|
|
* (which should mean identifiers are the same).
|
|
*/
|
|
hash = rht_head_hashfn(ht, tbl, obj_old, params);
|
|
if (hash != rht_head_hashfn(ht, tbl, obj_new, params))
|
|
return -EINVAL;
|
|
|
|
lock = rht_bucket_lock(tbl, hash);
|
|
|
|
spin_lock_bh(lock);
|
|
|
|
pprev = rht_bucket_var(tbl, hash);
|
|
rht_for_each_continue(he, *pprev, tbl, hash) {
|
|
if (he != obj_old) {
|
|
pprev = &he->next;
|
|
continue;
|
|
}
|
|
|
|
rcu_assign_pointer(obj_new->next, obj_old->next);
|
|
rcu_assign_pointer(*pprev, obj_new);
|
|
err = 0;
|
|
break;
|
|
}
|
|
|
|
spin_unlock_bh(lock);
|
|
|
|
return err;
|
|
}
|
|
|
|
/**
|
|
* rhashtable_replace_fast - replace an object in hash table
|
|
* @ht: hash table
|
|
* @obj_old: pointer to hash head inside object being replaced
|
|
* @obj_new: pointer to hash head inside object which is new
|
|
* @params: hash table parameters
|
|
*
|
|
* Replacing an object doesn't affect the number of elements in the hash table
|
|
* or bucket, so we don't need to worry about shrinking or expanding the
|
|
* table here.
|
|
*
|
|
* Returns zero on success, -ENOENT if the entry could not be found,
|
|
* -EINVAL if hash is not the same for the old and new objects.
|
|
*/
|
|
static inline int rhashtable_replace_fast(
|
|
struct rhashtable *ht, struct rhash_head *obj_old,
|
|
struct rhash_head *obj_new,
|
|
const struct rhashtable_params params)
|
|
{
|
|
struct bucket_table *tbl;
|
|
int err;
|
|
|
|
rcu_read_lock();
|
|
|
|
tbl = rht_dereference_rcu(ht->tbl, ht);
|
|
|
|
/* Because we have already taken (and released) the bucket
|
|
* lock in old_tbl, if we find that future_tbl is not yet
|
|
* visible then that guarantees the entry to still be in
|
|
* the old tbl if it exists.
|
|
*/
|
|
while ((err = __rhashtable_replace_fast(ht, tbl, obj_old,
|
|
obj_new, params)) &&
|
|
(tbl = rht_dereference_rcu(tbl->future_tbl, ht)))
|
|
;
|
|
|
|
rcu_read_unlock();
|
|
|
|
return err;
|
|
}
|
|
|
|
/* Obsolete function, do not use in new code. */
|
|
static inline int rhashtable_walk_init(struct rhashtable *ht,
|
|
struct rhashtable_iter *iter, gfp_t gfp)
|
|
{
|
|
rhashtable_walk_enter(ht, iter);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* rhltable_walk_enter - Initialise an iterator
|
|
* @hlt: 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.
|
|
*/
|
|
static inline void rhltable_walk_enter(struct rhltable *hlt,
|
|
struct rhashtable_iter *iter)
|
|
{
|
|
return rhashtable_walk_enter(&hlt->ht, iter);
|
|
}
|
|
|
|
/**
|
|
* rhltable_free_and_destroy - free elements and destroy hash list table
|
|
* @hlt: the hash list table to destroy
|
|
* @free_fn: callback to release resources of element
|
|
* @arg: pointer passed to free_fn
|
|
*
|
|
* See documentation for rhashtable_free_and_destroy.
|
|
*/
|
|
static inline void rhltable_free_and_destroy(struct rhltable *hlt,
|
|
void (*free_fn)(void *ptr,
|
|
void *arg),
|
|
void *arg)
|
|
{
|
|
return rhashtable_free_and_destroy(&hlt->ht, free_fn, arg);
|
|
}
|
|
|
|
static inline void rhltable_destroy(struct rhltable *hlt)
|
|
{
|
|
return rhltable_free_and_destroy(hlt, NULL, NULL);
|
|
}
|
|
|
|
#endif /* _LINUX_RHASHTABLE_H */
|