+++ /dev/null
-/* 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/rcupdate.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 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(p)
-
-#define rht_dereference_rcu(p, ht) \
- rcu_dereference(p)
-
-#define rht_dereference_bucket(p, tbl, hash) \
- rcu_dereference(p)
-
-#define rht_dereference_bucket_rcu(p, tbl, hash) \
- rcu_dereference(p)
-
-#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)
-{
- bit_spin_lock(0, (unsigned long *)bkt);
-}
-
-static inline void rht_lock_nested(struct bucket_table *tbl,
- struct rhash_lock_head __rcu **bucket,
- unsigned int subclass)
-{
- bit_spin_lock(0, (unsigned long *)bucket);
-}
-
-static inline void rht_unlock(struct bucket_table *tbl,
- struct rhash_lock_head __rcu **bkt)
-{
- bit_spin_unlock(0, (unsigned long *)bkt);
-}
-
-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(*bkt), 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;
- rcu_assign_pointer(*bkt, (void *)obj);
- preempt_enable();
- __release(bitlock);
- bit_spin_wake(0, (unsigned long *) bkt);
-}
-
-/**
- * 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 */
projects / bcachefs-tools-debian / blobdiff