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![Herbert Xu](/assets/img/avatar_default.png)
The opaque type rhash_lock_head should not be marked with __rcu because it can never be dereferenced. We should apply the RCU marking when we turn it into a pointer which can be dereferenced. This patch does exactly that. This fixes a number of sparse warnings as well as getting rid of some unnecessary RCU checking. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
1282 lines
38 KiB
C
1282 lines
38 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/bit_spinlock.h>
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#include <linux/rhashtable-types.h>
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/*
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* Objects in an rhashtable have an embedded struct rhash_head
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* which is linked into as hash chain from the hash table - or one
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* of two or more hash tables when the rhashtable is being resized.
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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 but otherwise stores the address of
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* the hash bucket. This allows us to be be sure we've found the end
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* of the right list.
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* The value stored in the hash bucket has BIT(0) used as a lock bit.
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* This bit must be atomically set before any changes are made to
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* the chain. To avoid dereferencing this pointer without clearing
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* the bit first, we use an opaque 'struct rhash_lock_head *' for the
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* pointer stored in the bucket. This struct needs to be defined so
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* that rcu_dereference() works on it, but it has no content so a
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* cast is needed for it to be useful. This ensures it isn't
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* used by mistake with clearing the lock bit first.
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*/
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struct rhash_lock_head {};
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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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* @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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u32 hash_rnd;
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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 lockdep_map dep_map;
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struct rhash_lock_head *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 give it an address, in which the bottom bit is
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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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* We never store the NULLS_MARKER in the hash table
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* itself as we need the lsb for locking.
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* Instead we store a NULL
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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) = NULL)
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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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#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_lock_head **rht_bucket_nested(const struct bucket_table *tbl,
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unsigned int hash);
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struct rhash_lock_head **__rht_bucket_nested(const struct bucket_table *tbl,
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unsigned int hash);
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struct rhash_lock_head **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_lock_head *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_lock_head **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_lock_head **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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* We lock a bucket by setting BIT(0) in the pointer - this is always
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* zero in real pointers. The NULLS mark is never stored in the bucket,
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* rather we store NULL if the bucket is empty.
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* bit_spin_locks do not handle contention well, but the whole point
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* of the hashtable design is to achieve minimum per-bucket contention.
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* A nested hash table might not have a bucket pointer. In that case
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* we cannot get a lock. For remove and replace the bucket cannot be
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* interesting and doesn't need locking.
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* For insert we allocate the bucket if this is the last bucket_table,
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* and then take the lock.
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* Sometimes we unlock a bucket by writing a new pointer there. In that
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* case we don't need to unlock, but we do need to reset state such as
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* local_bh. For that we have rht_assign_unlock(). As rcu_assign_pointer()
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* provides the same release semantics that bit_spin_unlock() provides,
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* this is safe.
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* When we write to a bucket without unlocking, we use rht_assign_locked().
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*/
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static inline void rht_lock(struct bucket_table *tbl,
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struct rhash_lock_head **bkt)
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{
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local_bh_disable();
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bit_spin_lock(0, (unsigned long *)bkt);
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lock_map_acquire(&tbl->dep_map);
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}
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static inline void rht_lock_nested(struct bucket_table *tbl,
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struct rhash_lock_head **bucket,
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unsigned int subclass)
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{
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local_bh_disable();
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bit_spin_lock(0, (unsigned long *)bucket);
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lock_acquire_exclusive(&tbl->dep_map, subclass, 0, NULL, _THIS_IP_);
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}
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static inline void rht_unlock(struct bucket_table *tbl,
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struct rhash_lock_head **bkt)
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{
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lock_map_release(&tbl->dep_map);
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bit_spin_unlock(0, (unsigned long *)bkt);
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local_bh_enable();
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}
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static inline struct rhash_head __rcu *__rht_ptr(
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struct rhash_lock_head *const *bkt)
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{
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return (struct rhash_head __rcu *)((unsigned long)*bkt & ~BIT(0));
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}
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/*
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* Where 'bkt' is a bucket and might be locked:
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* rht_ptr() dereferences that pointer and clears the lock bit.
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* rht_ptr_exclusive() dereferences in a context where exclusive
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* access is guaranteed, such as when destroying the table.
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*/
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static inline struct rhash_head *rht_ptr(
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struct rhash_lock_head *const *bkt,
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struct bucket_table *tbl,
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unsigned int hash)
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{
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struct rhash_head __rcu *p = __rht_ptr(bkt);
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if (!p)
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return RHT_NULLS_MARKER(bkt);
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return rht_dereference_bucket_rcu(p, tbl, hash);
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}
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static inline struct rhash_head *rht_ptr_exclusive(
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struct rhash_lock_head *const *bkt)
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{
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struct rhash_head __rcu *p = __rht_ptr(bkt);
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if (!p)
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return RHT_NULLS_MARKER(bkt);
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return rcu_dereference_protected(p, 1);
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}
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static inline void rht_assign_locked(struct rhash_lock_head **bkt,
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struct rhash_head *obj)
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{
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struct rhash_head __rcu **p = (struct rhash_head __rcu **)bkt;
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if (rht_is_a_nulls(obj))
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obj = NULL;
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rcu_assign_pointer(*p, (void *)((unsigned long)obj | BIT(0)));
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}
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static inline void rht_assign_unlock(struct bucket_table *tbl,
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struct rhash_lock_head **bkt,
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struct rhash_head *obj)
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{
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struct rhash_head __rcu **p = (struct rhash_head __rcu **)bkt;
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if (rht_is_a_nulls(obj))
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obj = NULL;
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lock_map_release(&tbl->dep_map);
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rcu_assign_pointer(*p, obj);
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preempt_enable();
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__release(bitlock);
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local_bh_enable();
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}
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/**
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* rht_for_each_from - iterate over hash chain from given head
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* @pos: the &struct rhash_head to use as a loop cursor.
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* @head: the &struct rhash_head to start 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_from(pos, head, tbl, hash) \
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for (pos = head; \
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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_from(pos, rht_ptr(rht_bucket(tbl, hash), tbl, hash), \
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tbl, hash)
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/**
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* rht_for_each_entry_from - iterate over hash chain from given head
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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 &struct rhash_head to start 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_from(tpos, pos, head, tbl, hash, member) \
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for (pos = head; \
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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_from(tpos, pos, \
|
|
rht_ptr(rht_bucket(tbl, hash), tbl, hash), \
|
|
tbl, hash, member)
|
|
|
|
/**
|
|
* rht_for_each_entry_safe - safely iterate over hash chain of given type
|
|
* @tpos: the type * to use as a loop cursor.
|
|
* @pos: the &struct rhash_head to use as a loop cursor.
|
|
* @next: the &struct rhash_head to use as next in loop cursor.
|
|
* @tbl: the &struct bucket_table
|
|
* @hash: the hash value / bucket index
|
|
* @member: name of the &struct rhash_head within the hashable struct.
|
|
*
|
|
* This hash chain list-traversal primitive allows for the looped code to
|
|
* remove the loop cursor from the list.
|
|
*/
|
|
#define rht_for_each_entry_safe(tpos, pos, next, tbl, hash, member) \
|
|
for (pos = rht_ptr(rht_bucket(tbl, hash), tbl, hash), \
|
|
next = !rht_is_a_nulls(pos) ? \
|
|
rht_dereference_bucket(pos->next, tbl, hash) : NULL; \
|
|
(!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
|
|
pos = next, \
|
|
next = !rht_is_a_nulls(pos) ? \
|
|
rht_dereference_bucket(pos->next, tbl, hash) : NULL)
|
|
|
|
/**
|
|
* rht_for_each_rcu_from - iterate over rcu hash chain from given head
|
|
* @pos: the &struct rhash_head to use as a loop cursor.
|
|
* @head: the &struct rhash_head to start from
|
|
* @tbl: the &struct bucket_table
|
|
* @hash: the hash value / bucket index
|
|
*
|
|
* 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_rcu_from(pos, head, tbl, hash) \
|
|
for (({barrier(); }), \
|
|
pos = head; \
|
|
!rht_is_a_nulls(pos); \
|
|
pos = rcu_dereference_raw(pos->next))
|
|
|
|
/**
|
|
* rht_for_each_rcu - iterate over rcu hash chain
|
|
* @pos: the &struct rhash_head to use as a loop cursor.
|
|
* @tbl: the &struct bucket_table
|
|
* @hash: the hash value / bucket index
|
|
*
|
|
* 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_rcu(pos, tbl, hash) \
|
|
for (({barrier(); }), \
|
|
pos = rht_ptr(rht_bucket(tbl, hash), tbl, hash); \
|
|
!rht_is_a_nulls(pos); \
|
|
pos = rcu_dereference_raw(pos->next))
|
|
|
|
/**
|
|
* rht_for_each_entry_rcu_from - iterated over rcu hash chain from given head
|
|
* @tpos: the type * to use as a loop cursor.
|
|
* @pos: the &struct rhash_head to use as a loop cursor.
|
|
* @head: the &struct rhash_head to start from
|
|
* @tbl: the &struct bucket_table
|
|
* @hash: the hash value / bucket index
|
|
* @member: name of the &struct rhash_head within the hashable struct.
|
|
*
|
|
* 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_from(tpos, pos, head, tbl, hash, member) \
|
|
for (({barrier(); }), \
|
|
pos = head; \
|
|
(!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
|
|
pos = rht_dereference_bucket_rcu(pos->next, tbl, hash))
|
|
|
|
/**
|
|
* rht_for_each_entry_rcu - iterate over rcu hash chain of given type
|
|
* @tpos: the type * to use as a loop cursor.
|
|
* @pos: the &struct rhash_head to use as a loop cursor.
|
|
* @tbl: the &struct bucket_table
|
|
* @hash: the hash value / bucket index
|
|
* @member: name of the &struct rhash_head within the hashable struct.
|
|
*
|
|
* 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_from(tpos, pos, \
|
|
rht_ptr(rht_bucket(tbl, hash), \
|
|
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_lock_head *const *bkt;
|
|
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);
|
|
bkt = rht_bucket(tbl, hash);
|
|
do {
|
|
rht_for_each_rcu_from(he, rht_ptr(bkt, tbl, hash), 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(bkt));
|
|
|
|
/* 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_lock_head **bkt;
|
|
struct rhash_head __rcu **pprev;
|
|
struct bucket_table *tbl;
|
|
struct rhash_head *head;
|
|
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);
|
|
elasticity = RHT_ELASTICITY;
|
|
bkt = rht_bucket_insert(ht, tbl, hash);
|
|
data = ERR_PTR(-ENOMEM);
|
|
if (!bkt)
|
|
goto out;
|
|
pprev = NULL;
|
|
rht_lock(tbl, bkt);
|
|
|
|
if (unlikely(rcu_access_pointer(tbl->future_tbl))) {
|
|
slow_path:
|
|
rht_unlock(tbl, bkt);
|
|
rcu_read_unlock();
|
|
return rhashtable_insert_slow(ht, key, obj);
|
|
}
|
|
|
|
rht_for_each_from(head, rht_ptr(bkt, tbl, hash), 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_unlock;
|
|
|
|
|
|
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);
|
|
if (pprev) {
|
|
rcu_assign_pointer(*pprev, obj);
|
|
rht_unlock(tbl, bkt);
|
|
} else
|
|
rht_assign_unlock(tbl, bkt, obj);
|
|
data = NULL;
|
|
goto out;
|
|
}
|
|
|
|
if (elasticity <= 0)
|
|
goto slow_path;
|
|
|
|
data = ERR_PTR(-E2BIG);
|
|
if (unlikely(rht_grow_above_max(ht, tbl)))
|
|
goto out_unlock;
|
|
|
|
if (unlikely(rht_grow_above_100(ht, tbl)))
|
|
goto slow_path;
|
|
|
|
/* Inserting at head of list makes unlocking free. */
|
|
head = rht_ptr(bkt, 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);
|
|
}
|
|
|
|
atomic_inc(&ht->nelems);
|
|
rht_assign_unlock(tbl, bkt, obj);
|
|
|
|
if (rht_grow_above_75(ht, tbl))
|
|
schedule_work(&ht->run_work);
|
|
|
|
data = NULL;
|
|
out:
|
|
rcu_read_unlock();
|
|
|
|
return data;
|
|
|
|
out_unlock:
|
|
rht_unlock(tbl, bkt);
|
|
goto out;
|
|
}
|
|
|
|
/**
|
|
* rhashtable_insert_fast - insert object into hash table
|
|
* @ht: hash table
|
|
* @obj: pointer to hash head inside object
|
|
* @params: hash table parameters
|
|
*
|
|
* Will take the per bucket bitlock to protect against mutual mutations
|
|
* on the same bucket. Multiple insertions may occur in parallel unless
|
|
* they map to the same bucket.
|
|
*
|
|
* 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 the per bucket bitlock to protect against mutual mutations
|
|
* on the same bucket. Multiple insertions may occur in parallel unless
|
|
* they map to the same bucket.
|
|
*
|
|
* 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 the per bucket bitlock to protect against mutual mutations
|
|
* on the same bucket. Multiple insertions may occur in parallel unless
|
|
* they map to the same bucket.
|
|
*
|
|
* 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
|
|
*
|
|
* 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
|
|
*
|
|
* 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_lock_head **bkt;
|
|
struct rhash_head __rcu **pprev;
|
|
struct rhash_head *he;
|
|
unsigned int hash;
|
|
int err = -ENOENT;
|
|
|
|
hash = rht_head_hashfn(ht, tbl, obj, params);
|
|
bkt = rht_bucket_var(tbl, hash);
|
|
if (!bkt)
|
|
return -ENOENT;
|
|
pprev = NULL;
|
|
rht_lock(tbl, bkt);
|
|
|
|
rht_for_each_from(he, rht_ptr(bkt, tbl, hash), 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;
|
|
}
|
|
}
|
|
|
|
if (pprev) {
|
|
rcu_assign_pointer(*pprev, obj);
|
|
rht_unlock(tbl, bkt);
|
|
} else {
|
|
rht_assign_unlock(tbl, bkt, obj);
|
|
}
|
|
goto unlocked;
|
|
}
|
|
|
|
rht_unlock(tbl, bkt);
|
|
unlocked:
|
|
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_lock_head **bkt;
|
|
struct rhash_head __rcu **pprev;
|
|
struct rhash_head *he;
|
|
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;
|
|
|
|
bkt = rht_bucket_var(tbl, hash);
|
|
if (!bkt)
|
|
return -ENOENT;
|
|
|
|
pprev = NULL;
|
|
rht_lock(tbl, bkt);
|
|
|
|
rht_for_each_from(he, rht_ptr(bkt, tbl, hash), tbl, hash) {
|
|
if (he != obj_old) {
|
|
pprev = &he->next;
|
|
continue;
|
|
}
|
|
|
|
rcu_assign_pointer(obj_new->next, obj_old->next);
|
|
if (pprev) {
|
|
rcu_assign_pointer(*pprev, obj_new);
|
|
rht_unlock(tbl, bkt);
|
|
} else {
|
|
rht_assign_unlock(tbl, bkt, obj_new);
|
|
}
|
|
err = 0;
|
|
goto unlocked;
|
|
}
|
|
|
|
rht_unlock(tbl, bkt);
|
|
|
|
unlocked:
|
|
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;
|
|
}
|
|
|
|
/**
|
|
* 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 */
|