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Diffstat (limited to 'include/linux/rhashtable.h')
| -rw-r--r-- | include/linux/rhashtable.h | 1275 |
1 files changed, 1275 insertions, 0 deletions
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h new file mode 100644 index 000000000..68dab3e08 --- /dev/null +++ b/include/linux/rhashtable.h @@ -0,0 +1,1275 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Resizable, Scalable, Concurrent Hash Table + * + * Copyright (c) 2015-2016 Herbert Xu <herbert@gondor.apana.org.au> + * Copyright (c) 2014-2015 Thomas Graf <tgraf@suug.ch> + * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net> + * + * Code partially derived from nft_hash + * Rewritten with rehash code from br_multicast plus single list + * pointer as suggested by Josh Triplett + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#ifndef _LINUX_RHASHTABLE_H +#define _LINUX_RHASHTABLE_H + +#include <linux/err.h> +#include <linux/errno.h> +#include <linux/jhash.h> +#include <linux/list_nulls.h> +#include <linux/workqueue.h> +#include <linux/rculist.h> +#include <linux/bit_spinlock.h> + +#include <linux/rhashtable-types.h> +/* + * Objects in an rhashtable have an embedded struct rhash_head + * which is linked into as hash chain from the hash table - or one + * of two or more hash tables when the rhashtable is being resized. + * The end of the chain is marked with a special nulls marks which has + * the least significant bit set but otherwise stores the address of + * the hash bucket. This allows us to be sure we've found the end + * of the right list. + * The value stored in the hash bucket has BIT(0) used as a lock bit. + * This bit must be atomically set before any changes are made to + * the chain. To avoid dereferencing this pointer without clearing + * the bit first, we use an opaque 'struct rhash_lock_head *' for the + * pointer stored in the bucket. This struct needs to be defined so + * that rcu_dereference() works on it, but it has no content so a + * cast is needed for it to be useful. This ensures it isn't + * used by mistake with clearing the lock bit first. + */ +struct rhash_lock_head {}; + +/* Maximum chain length before rehash + * + * The maximum (not average) chain length grows with the size of the hash + * table, at a rate of (log N)/(log log N). + * + * The value of 16 is selected so that even if the hash table grew to + * 2^32 you would not expect the maximum chain length to exceed it + * unless we are under attack (or extremely unlucky). + * + * As this limit is only to detect attacks, we don't need to set it to a + * lower value as you'd need the chain length to vastly exceed 16 to have + * any real effect on the system. + */ +#define RHT_ELASTICITY 16u + +/** + * struct bucket_table - Table of hash buckets + * @size: Number of hash buckets + * @nest: Number of bits of first-level nested table. + * @rehash: Current bucket being rehashed + * @hash_rnd: Random seed to fold into hash + * @walkers: List of active walkers + * @rcu: RCU structure for freeing the table + * @future_tbl: Table under construction during rehashing + * @ntbl: Nested table used when out of memory. + * @buckets: size * hash buckets + */ +struct bucket_table { + unsigned int size; + unsigned int nest; + u32 hash_rnd; + struct list_head walkers; + struct rcu_head rcu; + + struct bucket_table __rcu *future_tbl; + + struct lockdep_map dep_map; + + struct rhash_lock_head __rcu *buckets[] ____cacheline_aligned_in_smp; +}; + +/* + * NULLS_MARKER() expects a hash value with the low + * bits mostly likely to be significant, and it discards + * the msb. + * We give it an address, in which the bottom bit is + * always 0, and the msb might be significant. + * So we shift the address down one bit to align with + * expectations and avoid losing a significant bit. + * + * We never store the NULLS_MARKER in the hash table + * itself as we need the lsb for locking. + * Instead we store a NULL + */ +#define RHT_NULLS_MARKER(ptr) \ + ((void *)NULLS_MARKER(((unsigned long) (ptr)) >> 1)) +#define INIT_RHT_NULLS_HEAD(ptr) \ + ((ptr) = NULL) + +static inline bool rht_is_a_nulls(const struct rhash_head *ptr) +{ + return ((unsigned long) ptr & 1); +} + +static inline void *rht_obj(const struct rhashtable *ht, + const struct rhash_head *he) +{ + return (char *)he - ht->p.head_offset; +} + +static inline unsigned int rht_bucket_index(const struct bucket_table *tbl, + unsigned int hash) +{ + return hash & (tbl->size - 1); +} + +static inline unsigned int rht_key_get_hash(struct rhashtable *ht, + const void *key, const struct rhashtable_params params, + unsigned int hash_rnd) +{ + unsigned int hash; + + /* params must be equal to ht->p if it isn't constant. */ + if (!__builtin_constant_p(params.key_len)) + hash = ht->p.hashfn(key, ht->key_len, hash_rnd); + else if (params.key_len) { + unsigned int key_len = params.key_len; + + if (params.hashfn) + hash = params.hashfn(key, key_len, hash_rnd); + else if (key_len & (sizeof(u32) - 1)) + hash = jhash(key, key_len, hash_rnd); + else + hash = jhash2(key, key_len / sizeof(u32), hash_rnd); + } else { + unsigned int key_len = ht->p.key_len; + + if (params.hashfn) + hash = params.hashfn(key, key_len, hash_rnd); + else + hash = jhash(key, key_len, hash_rnd); + } + + return hash; +} + +static inline unsigned int rht_key_hashfn( + struct rhashtable *ht, const struct bucket_table *tbl, + const void *key, const struct rhashtable_params params) +{ + unsigned int hash = rht_key_get_hash(ht, key, params, tbl->hash_rnd); + + return rht_bucket_index(tbl, hash); +} + +static inline unsigned int rht_head_hashfn( + struct rhashtable *ht, const struct bucket_table *tbl, + const struct rhash_head *he, const struct rhashtable_params params) +{ + const char *ptr = rht_obj(ht, he); + + return likely(params.obj_hashfn) ? + rht_bucket_index(tbl, params.obj_hashfn(ptr, params.key_len ?: + ht->p.key_len, + tbl->hash_rnd)) : + rht_key_hashfn(ht, tbl, ptr + params.key_offset, params); +} + +/** + * rht_grow_above_75 - returns true if nelems > 0.75 * table-size + * @ht: hash table + * @tbl: current table + */ +static inline bool rht_grow_above_75(const struct rhashtable *ht, + const struct bucket_table *tbl) +{ + /* Expand table when exceeding 75% load */ + return atomic_read(&ht->nelems) > (tbl->size / 4 * 3) && + (!ht->p.max_size || tbl->size < ht->p.max_size); +} + +/** + * rht_shrink_below_30 - returns true if nelems < 0.3 * table-size + * @ht: hash table + * @tbl: current table + */ +static inline bool rht_shrink_below_30(const struct rhashtable *ht, + const struct bucket_table *tbl) +{ + /* Shrink table beneath 30% load */ + return atomic_read(&ht->nelems) < (tbl->size * 3 / 10) && + tbl->size > ht->p.min_size; +} + +/** + * rht_grow_above_100 - returns true if nelems > table-size + * @ht: hash table + * @tbl: current table + */ +static inline bool rht_grow_above_100(const struct rhashtable *ht, + const struct bucket_table *tbl) +{ + return atomic_read(&ht->nelems) > tbl->size && + (!ht->p.max_size || tbl->size < ht->p.max_size); +} + +/** + * rht_grow_above_max - returns true if table is above maximum + * @ht: hash table + * @tbl: current table + */ +static inline bool rht_grow_above_max(const struct rhashtable *ht, + const struct bucket_table *tbl) +{ + return atomic_read(&ht->nelems) >= ht->max_elems; +} + +#ifdef CONFIG_PROVE_LOCKING +int lockdep_rht_mutex_is_held(struct rhashtable *ht); +int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash); +#else +static inline int lockdep_rht_mutex_is_held(struct rhashtable *ht) +{ + return 1; +} + +static inline int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, + u32 hash) +{ + return 1; +} +#endif /* CONFIG_PROVE_LOCKING */ + +void *rhashtable_insert_slow(struct rhashtable *ht, const void *key, + struct rhash_head *obj); + +void rhashtable_walk_enter(struct rhashtable *ht, + struct rhashtable_iter *iter); +void rhashtable_walk_exit(struct rhashtable_iter *iter); +int rhashtable_walk_start_check(struct rhashtable_iter *iter) __acquires(RCU); + +static inline void rhashtable_walk_start(struct rhashtable_iter *iter) +{ + (void)rhashtable_walk_start_check(iter); +} + +void *rhashtable_walk_next(struct rhashtable_iter *iter); +void *rhashtable_walk_peek(struct rhashtable_iter *iter); +void rhashtable_walk_stop(struct rhashtable_iter *iter) __releases(RCU); + +void rhashtable_free_and_destroy(struct rhashtable *ht, + void (*free_fn)(void *ptr, void *arg), + void *arg); +void rhashtable_destroy(struct rhashtable *ht); + +struct rhash_lock_head __rcu **rht_bucket_nested( + const struct bucket_table *tbl, unsigned int hash); +struct rhash_lock_head __rcu **__rht_bucket_nested( + const struct bucket_table *tbl, unsigned int hash); +struct rhash_lock_head __rcu **rht_bucket_nested_insert( + struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash); + +#define rht_dereference(p, ht) \ + rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht)) + +#define rht_dereference_rcu(p, ht) \ + rcu_dereference_check(p, lockdep_rht_mutex_is_held(ht)) + +#define rht_dereference_bucket(p, tbl, hash) \ + rcu_dereference_protected(p, lockdep_rht_bucket_is_held(tbl, hash)) + +#define rht_dereference_bucket_rcu(p, tbl, hash) \ + rcu_dereference_check(p, lockdep_rht_bucket_is_held(tbl, hash)) + +#define rht_entry(tpos, pos, member) \ + ({ tpos = container_of(pos, typeof(*tpos), member); 1; }) + +static inline struct rhash_lock_head __rcu *const *rht_bucket( + const struct bucket_table *tbl, unsigned int hash) +{ + return unlikely(tbl->nest) ? rht_bucket_nested(tbl, hash) : + &tbl->buckets[hash]; +} + +static inline struct rhash_lock_head __rcu **rht_bucket_var( + struct bucket_table *tbl, unsigned int hash) +{ + return unlikely(tbl->nest) ? __rht_bucket_nested(tbl, hash) : + &tbl->buckets[hash]; +} + +static inline struct rhash_lock_head __rcu **rht_bucket_insert( + struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash) +{ + return unlikely(tbl->nest) ? rht_bucket_nested_insert(ht, tbl, hash) : + &tbl->buckets[hash]; +} + +/* + * We lock a bucket by setting BIT(0) in the pointer - this is always + * zero in real pointers. The NULLS mark is never stored in the bucket, + * rather we store NULL if the bucket is empty. + * bit_spin_locks do not handle contention well, but the whole point + * of the hashtable design is to achieve minimum per-bucket contention. + * A nested hash table might not have a bucket pointer. In that case + * we cannot get a lock. For remove and replace the bucket cannot be + * interesting and doesn't need locking. + * For insert we allocate the bucket if this is the last bucket_table, + * and then take the lock. + * Sometimes we unlock a bucket by writing a new pointer there. In that + * case we don't need to unlock, but we do need to reset state such as + * local_bh. For that we have rht_assign_unlock(). As rcu_assign_pointer() + * provides the same release semantics that bit_spin_unlock() provides, + * this is safe. + * When we write to a bucket without unlocking, we use rht_assign_locked(). + */ + +static inline void rht_lock(struct bucket_table *tbl, + struct rhash_lock_head __rcu **bkt) +{ + local_bh_disable(); + bit_spin_lock(0, (unsigned long *)bkt); + lock_map_acquire(&tbl->dep_map); +} + +static inline void rht_lock_nested(struct bucket_table *tbl, + struct rhash_lock_head __rcu **bucket, + unsigned int subclass) +{ + local_bh_disable(); + bit_spin_lock(0, (unsigned long *)bucket); + lock_acquire_exclusive(&tbl->dep_map, subclass, 0, NULL, _THIS_IP_); +} + +static inline void rht_unlock(struct bucket_table *tbl, + struct rhash_lock_head __rcu **bkt) +{ + lock_map_release(&tbl->dep_map); + bit_spin_unlock(0, (unsigned long *)bkt); + local_bh_enable(); +} + +static inline struct rhash_head *__rht_ptr( + struct rhash_lock_head *p, struct rhash_lock_head __rcu *const *bkt) +{ + return (struct rhash_head *) + ((unsigned long)p & ~BIT(0) ?: + (unsigned long)RHT_NULLS_MARKER(bkt)); +} + +/* + * Where 'bkt' is a bucket and might be locked: + * rht_ptr_rcu() dereferences that pointer and clears the lock bit. + * rht_ptr() dereferences in a context where the bucket is locked. + * rht_ptr_exclusive() dereferences in a context where exclusive + * access is guaranteed, such as when destroying the table. + */ +static inline struct rhash_head *rht_ptr_rcu( + struct rhash_lock_head __rcu *const *bkt) +{ + return __rht_ptr(rcu_dereference(*bkt), bkt); +} + +static inline struct rhash_head *rht_ptr( + struct rhash_lock_head __rcu *const *bkt, + struct bucket_table *tbl, + unsigned int hash) +{ + return __rht_ptr(rht_dereference_bucket(*bkt, tbl, hash), bkt); +} + +static inline struct rhash_head *rht_ptr_exclusive( + struct rhash_lock_head __rcu *const *bkt) +{ + return __rht_ptr(rcu_dereference_protected(*bkt, 1), bkt); +} + +static inline void rht_assign_locked(struct rhash_lock_head __rcu **bkt, + struct rhash_head *obj) +{ + if (rht_is_a_nulls(obj)) + obj = NULL; + rcu_assign_pointer(*bkt, (void *)((unsigned long)obj | BIT(0))); +} + +static inline void rht_assign_unlock(struct bucket_table *tbl, + struct rhash_lock_head __rcu **bkt, + struct rhash_head *obj) +{ + if (rht_is_a_nulls(obj)) + obj = NULL; + lock_map_release(&tbl->dep_map); + rcu_assign_pointer(*bkt, (void *)obj); + preempt_enable(); + __release(bitlock); + local_bh_enable(); +} + +/** + * rht_for_each_from - iterate over 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 + */ +#define rht_for_each_from(pos, head, tbl, hash) \ + for (pos = head; \ + !rht_is_a_nulls(pos); \ + pos = rht_dereference_bucket((pos)->next, tbl, hash)) + +/** + * rht_for_each - iterate over hash chain + * @pos: the &struct rhash_head to use as a loop cursor. + * @tbl: the &struct bucket_table + * @hash: the hash value / bucket index + */ +#define rht_for_each(pos, tbl, hash) \ + rht_for_each_from(pos, rht_ptr(rht_bucket(tbl, hash), tbl, hash), \ + tbl, hash) + +/** + * rht_for_each_entry_from - iterate over 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. + */ +#define rht_for_each_entry_from(tpos, pos, head, tbl, hash, member) \ + for (pos = head; \ + (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \ + pos = rht_dereference_bucket((pos)->next, tbl, hash)) + +/** + * rht_for_each_entry - 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. + * @tbl: the &struct bucket_table + * @hash: the hash value / bucket index + * @member: name of the &struct rhash_head within the hashable struct. + */ +#define rht_for_each_entry(tpos, pos, tbl, hash, member) \ + 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_rcu(rht_bucket(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_rcu(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_lock_head __rcu *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_rcu(bkt), 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 __rcu **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 + * @key: key + * @obj: pointer to hash head inside object + * @params: hash table parameters + * + * 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 __rcu **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 __rcu **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 */ |