/*
* 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/atomic.h>
#include <linux/compiler.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/jhash.h>
#include <linux/list_nulls.h>
#include <linux/workqueue.h>
#include <linux/mutex.h>
#include <linux/rculist.h>
/*
* The end of the chain is marked with a special nulls marks which has
* the following format:
*
* +-------+-----------------------------------------------------+-+
* | Base | Hash |1|
* +-------+-----------------------------------------------------+-+
*
* Base (4 bits) : Reserved to distinguish between multiple tables.
* Specified via &struct rhashtable_params.nulls_base.
* Hash (27 bits): Full hash (unmasked) of first element added to bucket
* 1 (1 bit) : Nulls marker (always set)
*
* The remaining bits of the next pointer remain unused for now.
*/
#define RHT_BASE_BITS 4
#define RHT_HASH_BITS 27
#define RHT_BASE_SHIFT RHT_HASH_BITS
/* Base bits plus 1 bit for nulls marker */
#define RHT_HASH_RESERVED_SPACE (RHT_BASE_BITS + 1)
/* 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 rhash_head {
struct rhash_head __rcu *next;
};
struct rhlist_head {
struct rhash_head rhead;
struct rhlist_head __rcu *next;
};
/**
* 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
* @locks_mask: Mask to apply before accessing locks[]
* @locks: Array of spinlocks protecting individual buckets
* @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;
unsigned int rehash;
u32 hash_rnd;
unsigned int locks_mask;
spinlock_t *locks;
struct list_head walkers;
struct rcu_head rcu;
struct bucket_table __rcu *future_tbl;
struct rhash_head __rcu *buckets[] ____cacheline_aligned_in_smp;
};
/**
* struct rhashtable_compare_arg - Key for the function rhashtable_compare
* @ht: Hash table
* @key: Key to compare against
*/
struct rhashtable_compare_arg {
struct rhashtable *ht;
const void *key;
};
typedef u32 (*rht_hashfn_t)(const void *data, u32 len, u32 seed);
typedef u32 (*rht_obj_hashfn_t)(const void *data, u32 len, u32 seed);
typedef int (*rht_obj_cmpfn_t)(struct rhashtable_compare_arg *arg,
const void *obj);
struct rhashtable;
/**
* struct rhashtable_params - Hash table construction parameters
* @nelem_hint: Hint on number of elements, should be 75% of desired size
* @key_len: Length of key
* @key_offset: Offset of key in struct to be hashed
* @head_offset: Offset of rhash_head in struct to be hashed
* @max_size: Maximum size while expanding
* @min_size: Minimum size while shrinking
* @locks_mul: Number of bucket locks to allocate per cpu (default: 32)
* @automatic_shrinking: Enable automatic shrinking of tables
* @nulls_base: Base value to generate nulls marker
* @hashfn: Hash function (default: jhash2 if !(key_len % 4), or jhash)
* @obj_hashfn: Function to hash object
* @obj_cmpfn: Function to compare key with object
*/
struct rhashtable_params {
u16 nelem_hint;
u16 key_len;
u16 key_offset;
u16 head_offset;
unsigned int max_size;
u16 min_size;
bool automatic_shrinking;
u8 locks_mul;
u32 nulls_base;
rht_hashfn_t hashfn;
rht_obj_hashfn_t obj_hashfn;
rht_obj_cmpfn_t obj_cmpfn;
};
/**
* struct rhashtable - Hash table handle
* @tbl: Bucket table
* @nelems: Number of elements in table
* @key_len: Key length for hashfn
* @p: Configuration parameters
* @max_elems: Maximum number of elements in table
* @rhlist: True if this is an rhltable
* @run_work: Deferred worker to expand/shrink asynchronously
* @mutex: Mutex to protect current/future table swapping
* @lock: Spin lock to protect walker list
*/
struct rhashtable {
struct bucket_table __rcu *tbl;
atomic_t nelems;
unsigned int key_len;
struct rhashtable_params p;
unsigned int max_elems;
bool rhlist;
struct work_struct run_work;
struct mutex mutex;
spinlock_t lock;
};
/**
* struct rhltable - Hash table with duplicate objects in a list
* @ht: Underlying rhtable
*/
struct rhltable {
struct rhashtable ht;
};
/**
* struct rhashtable_walker - Hash table walker
* @list: List entry on list of walkers
* @tbl: The table that we were walking over
*/
struct rhashtable_walker {
struct list_head list;
struct bucket_table *tbl;
};
/**
* struct rhashtable_iter - Hash table iterator
* @ht: Table to iterate through
* @p: Current pointer
* @list: Current hash list pointer
* @walker: Associated rhashtable walker
* @slot: Current slot
* @skip: Number of entries to skip in slot
*/
struct rhashtable_iter {
struct rhashtable *ht;
struct rhash_head *p;
struct rhlist_head *list;
struct rhashtable_walker walker;
unsigned int slot;
unsigned int skip;
};
static inline unsigned long rht_marker(const struct rhashtable *ht, u32 hash)
{
return NULLS_MARKER(ht->p.nulls_base + hash);
}
#define INIT_RHT_NULLS_HEAD(ptr, ht, hash) \
((ptr) = (typeof(ptr)) rht_marker(ht, hash))
static inline bool rht_is_a_nulls(const struct rhash_head *ptr)
{
return ((unsigned long) ptr & 1);
}
static inline unsigned long rht_get_nulls_value(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 >> RHT_HASH_RESERVED_SPACE) & (tbl->size - 1);
}
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;
/* 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, tbl->hash_rnd);
else if (params.key_len) {
unsigned int key_len = params.key_len;
if (params.hashfn)
hash = params.hashfn(key, key_len, tbl->hash_rnd);
else if (key_len & (sizeof(u32) - 1))
hash = jhash(key, key_len, tbl->hash_rnd);
else
hash = jhash2(key, key_len / sizeof(u32),
tbl->hash_rnd);
} else {
unsigned int key_len = ht->p.key_len;
if (params.hashfn)
hash = params.hashfn(key, key_len, tbl->hash_rnd);
else
hash = jhash(key, key_len, 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;
}
/* The bucket lock is selected based on the hash and protects mutations
* on a group of hash buckets.
*
* A maximum of tbl->size/2 bucket locks is allocated. This ensures that
* a single lock always covers both buckets which may both contains
* entries which link to the same bucket of the old table during resizing.
* This allows to simplify the locking as locking the bucket in both
* tables during resize always guarantee protection.
*
* IMPORTANT: When holding the bucket lock of both the old and new table
* during expansions and shrinking, the old bucket lock must always be
* acquired first.
*/
static inline spinlock_t *rht_bucket_lock(const struct bucket_table *tbl,
unsigned int hash)
{
return &tbl->locks[hash & tbl->locks_mask];
}
#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 */
int rhashtable_init(struct rhashtable *ht,
const struct rhashtable_params *params);
int rhltable_init(struct rhltable *hlt,
const struct rhashtable_params *params);
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(struct rhashtable_iter *iter) __acquires(RCU);
void *rhashtable_walk_next(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_head __rcu **rht_bucket_nested(const struct bucket_table *tbl,
unsigned int hash);
struct rhash_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_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_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_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];
}
/**
* rht_for_each_continue - continue iterating over hash chain
* @pos: the &struct rhash_head to use as a loop cursor.
* @head: the previous &struct rhash_head to continue from
* @tbl: the &struct bucket_table
* @hash: the hash value / bucket index
*/
#define rht_for_each_continue(pos, head, tbl, hash) \
for (pos = rht_dereference_bucket(head, tbl, hash); \
!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_continue(pos, *rht_bucket(tbl, hash), tbl, hash)
/**
* rht_for_each_entry_continue - continue iterating over hash chain
* @tpos: the type * to use as a loop cursor.
* @pos: the &struct rhash_head to use as a loop cursor.
* @head: the previous &struct rhash_head to continue 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_continue(tpos, pos, head, tbl, hash, member) \
for (pos = rht_dereference_bucket(head, tbl, hash); \
(!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_continue(tpos, pos, *rht_bucket(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_dereference_bucket(*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_continue - continue iterating over rcu hash chain
* @pos: the &struct rhash_head to use as a loop cursor.
* @head: the previous &struct rhash_head to continue 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_continue(pos, head, tbl, hash) \
for (({barrier(); }), \
pos = rht_dereference_bucket_rcu(head, tbl, hash); \
!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) \
rht_for_each_rcu_continue(pos, *rht_bucket(tbl, hash), tbl, hash)
/**
* rht_for_each_entry_rcu_continue - continue iterating over rcu hash chain
* @tpos: the type * to use as a loop cursor.
* @pos: the &struct rhash_head to use as a loop cursor.
* @head: the previous &struct rhash_head to continue 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_continue(tpos, pos, head, tbl, hash, member) \
for (({barrier(); }), \
pos = rht_dereference_bucket_rcu(head, tbl, hash); \
(!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_continue(tpos, pos, *rht_bucket(tbl, hash), \
tbl, hash, member)
/**
* rhl_for_each_rcu - iterate over rcu hash table list
* @pos: the &struct rlist_head to use as a loop cursor.
* @list: the head of the list
*
* This hash chain list-traversal primitive should be used on the
* list returned by rhltable_lookup.
*/
#define rhl_for_each_rcu(pos, list) \
for (pos = list; pos; pos = rcu_dereference_raw(pos->next))
/**
* rhl_for_each_entry_rcu - iterate over rcu hash table list of given type
* @tpos: the type * to use as a loop cursor.
* @pos: the &struct rlist_head to use as a loop cursor.
* @list: the head of the list
* @member: name of the &struct rlist_head within the hashable struct.
*
* This hash chain list-traversal primitive should be used on the
* list returned by rhltable_lookup.
*/
#define rhl_for_each_entry_rcu(tpos, pos, list, member) \
for (pos = list; pos && rht_entry(tpos, pos, member); \
pos = rcu_dereference_raw(pos->next))
static inline int rhashtable_compare(struct rhashtable_compare_arg *arg,
const void *obj)
{
struct rhashtable *ht = arg->ht;
const char *ptr = obj;
return memcmp(ptr + ht->p.key_offset, arg->key, ht->p.key_len);
}
/* Internal function, do not use. */
static inline struct rhash_head *__rhashtable_lookup(
struct rhashtable *ht, const void *key,
const struct rhashtable_params params)
{
struct rhashtable_compare_arg arg = {
.ht = ht,
.key = key,
};
struct 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);
rht_for_each_rcu(he, tbl, hash) {
if (params.obj_cmpfn ?
params.obj_cmpfn(&arg, rht_obj(ht, he)) :
rhashtable_compare(&arg, rht_obj(ht, he)))
continue;
return he;
}
/* Ensure we see any new tables. */
smp_rmb();
tbl = rht_dereference_rcu(tbl->future_tbl, ht);
if (unlikely(tbl))
goto restart;
return NULL;
}
/**
* rhashtable_lookup - search hash table
* @ht: hash table
* @key: the pointer to the key
* @params: hash table parameters
*
* Computes the hash value for the key and traverses the bucket chain looking
* for a entry with an identical key. The first matching entry is returned.
*
* This must only be called under the RCU read lock.
*
* Returns the first entry on which the compare function returned true.
*/
static inline void *rhashtable_lookup(
struct rhashtable *ht, const void *key,
const struct rhashtable_params params)
{
struct rhash_head *he = __rhashtable_lookup(ht, key, params);
return he ? rht_obj(ht, he) : NULL;
}
/**
* rhashtable_lookup_fast - search hash table, without RCU read lock
* @ht: hash table
* @key: the pointer to the key
* @params: hash table parameters
*
* Computes the hash value for the key and traverses the bucket chain looking
* for a entry with an identical key. The first matching entry is returned.
*
* Only use this function when you have other mechanisms guaranteeing
* that the object won't go away after the RCU read lock is released.
*
* Returns the first entry on which the compare function returned true.
*/
static inline void *rhashtable_lookup_fast(
struct rhashtable *ht, const void *key,
const struct rhashtable_params params)
{
void *obj;
rcu_read_lock();
obj = rhashtable_lookup(ht, key, params);
rcu_read_unlock();
return obj;
}
/**
* rhltable_lookup - search hash list table
* @hlt: hash table
* @key: the pointer to the key
* @params: hash table parameters
*
* Computes the hash value for the key and traverses the bucket chain looking
* for a entry with an identical key. All matching entries are returned
* in a list.
*
* This must only be called under the RCU read lock.
*
* Returns the list of entries that match the given key.
*/
static inline struct rhlist_head *rhltable_lookup(
struct rhltable *hlt, const void *key,
const struct rhashtable_params params)
{
struct rhash_head *he = __rhashtable_lookup(&hlt->ht, key, params);
return he ? container_of(he, struct rhlist_head, rhead) : NULL;
}
/* Internal function, please use rhashtable_insert_fast() instead. This
* function returns the existing element already in hashes in there is a clash,
* otherwise it returns an error via ERR_PTR().
*/
static inline void *__rhashtable_insert_fast(
struct rhashtable *ht, const void *key, struct rhash_head *obj,
const struct rhashtable_params params, bool rhlist)
{
struct rhashtable_compare_arg arg = {
.ht = ht,
.key = key,
};
struct rhash_head __rcu **pprev;
struct bucket_table *tbl;
struct rhash_head *head;
spinlock_t *lock;
unsigned int hash;
int elasticity;
void *data;
rcu_read_lock();
tbl = rht_dereference_rcu(ht->tbl, ht);
hash = rht_head_hashfn(ht, tbl, obj, params);
lock = rht_bucket_lock(tbl, hash);
spin_lock_bh(lock);
if (unlikely(rht_dereference_bucket(tbl->future_tbl, tbl, hash))) {
slow_path:
spin_unlock_bh(lock);
rcu_read_unlock();
return rhashtable_insert_slow(ht, key, obj);
}
elasticity = RHT_ELASTICITY;
pprev = rht_bucket_insert(ht, tbl, hash);
data = ERR_PTR(-ENOMEM);
if (!pprev)
goto out;
rht_for_each_continue(head, *pprev, tbl, hash) {
struct rhlist_head *plist;
struct rhlist_head *list;
elasticity--;
if (!key ||
(params.obj_cmpfn ?
params.obj_cmpfn(&arg, rht_obj(ht, head)) :
rhashtable_compare(&arg, rht_obj(ht, head))))
continue;
data = rht_obj(ht, head);
if (!rhlist)
goto out;
list = container_of(obj, struct rhlist_head, rhead);
plist = container_of(head, struct rhlist_head, rhead);
RCU_INIT_POINTER(list->next, plist);
head = rht_dereference_bucket(head->next, tbl, hash);
RCU_INIT_POINTER(list->rhead.next, head);
rcu_assign_pointer(*pprev, obj);
goto good;
}
if (elasticity <= 0)
goto slow_path;
data = ERR_PTR(-E2BIG);
if (unlikely(rht_grow_above_max(ht, tbl)))
goto out;
if (unlikely(rht_grow_above_100(ht, tbl)))
goto slow_path;
head = rht_dereference_bucket(*pprev, tbl, hash);
RCU_INIT_POINTER(obj->next, head);
if (rhlist) {
struct rhlist_head *list;
list = container_of(obj, struct rhlist_head, rhead);
RCU_INIT_POINTER(list->next, NULL);
}
rcu_assign_pointer(*pprev, obj);
atomic_inc(&ht->nelems);
if (rht_grow_above_75(ht, tbl))
schedule_work(&ht->run_work);
good:
data = NULL;
out:
spin_unlock_bh(lock);
rcu_read_unlock();
return data;
}
/**
* rhashtable_insert_fast - insert object into hash table
* @ht: hash table
* @obj: pointer to hash head inside object
* @params: hash table parameters
*
* Will take a per bucket spinlock to protect against mutual mutations
* on the same bucket. Multiple insertions may occur in parallel unless
* they map to the same bucket lock.
*
* It is safe to call this function from atomic context.
*
* Will trigger an automatic deferred table resizing if the size grows
* beyond the watermark indicated by grow_decision() which can be passed
* to rhashtable_init().
*/
static inline int rhashtable_insert_fast(
struct rhashtable *ht, struct rhash_head *obj,
const struct rhashtable_params params)
{
void *ret;
ret = __rhashtable_insert_fast(ht, NULL, obj, params, false);
if (IS_ERR(ret))
return PTR_ERR(ret);
return ret == NULL ? 0 : -EEXIST;
}
/**
* rhltable_insert_key - insert object into hash list table
* @hlt: hash list table
* @key: the pointer to the key
* @list: pointer to hash list head inside object
* @params: hash table parameters
*
* Will take a per bucket spinlock to protect against mutual mutations
* on the same bucket. Multiple insertions may occur in parallel unless
* they map to the same bucket lock.
*
* It is safe to call this function from atomic context.
*
* Will trigger an automatic deferred table resizing if the size grows
* beyond the watermark indicated by grow_decision() which can be passed
* to rhashtable_init().
*/
static inline int rhltable_insert_key(
struct rhltable *hlt, const void *key, struct rhlist_head *list,
const struct rhashtable_params params)
{
return PTR_ERR(__rhashtable_insert_fast(&hlt->ht, key, &list->rhead,
params, true));
}
/**
* rhltable_insert - insert object into hash list table
* @hlt: hash list table
* @list: pointer to hash list head inside object
* @params: hash table parameters
*
* Will take a per bucket spinlock to protect against mutual mutations
* on the same bucket. Multiple insertions may occur in parallel unless
* they map to the same bucket lock.
*
* It is safe to call this function from atomic context.
*
* Will trigger an automatic deferred table resizing if the size grows
* beyond the watermark indicated by grow_decision() which can be passed
* to rhashtable_init().
*/
static inline int rhltable_insert(
struct rhltable *hlt, struct rhlist_head *list,
const struct rhashtable_params params)
{
const char *key = rht_obj(&hlt->ht, &list->rhead);
key += params.key_offset;
return rhltable_insert_key(hlt, key, list, params);
}
/**
* rhashtable_lookup_insert_fast - lookup and insert object into hash table
* @ht: hash table
* @obj: pointer to hash head inside object
* @params: hash table parameters
*
* Locks down the bucket chain in both the old and new table if a resize
* is in progress to ensure that writers can't remove from the old table
* and can't insert to the new table during the atomic operation of search
* and insertion. Searches for duplicates in both the old and new table if
* a resize is in progress.
*
* This lookup function may only be used for fixed key hash table (key_len
* parameter set). It will BUG() if used inappropriately.
*
* It is safe to call this function from atomic context.
*
* Will trigger an automatic deferred table resizing if the size grows
* beyond the watermark indicated by grow_decision() which can be passed
* to rhashtable_init().
*/
static inline int rhashtable_lookup_insert_fast(
struct rhashtable *ht, struct rhash_head *obj,
const struct rhashtable_params params)
{
const char *key = rht_obj(ht, obj);
void *ret;
BUG_ON(ht->p.obj_hashfn);
ret = __rhashtable_insert_fast(ht, key + ht->p.key_offset, obj, params,
false);
if (IS_ERR(ret))
return PTR_ERR(ret);
return ret == NULL ? 0 : -EEXIST;
}
/**
* rhashtable_lookup_get_insert_fast - lookup and insert object into hash table
* @ht: hash table
* @obj: pointer to hash head inside object
* @params: hash table parameters
*
* Just like rhashtable_lookup_insert_fast(), but this function returns the
* object if it exists, NULL if it did not and the insertion was successful,
* and an ERR_PTR otherwise.
*/
static inline void *rhashtable_lookup_get_insert_fast(
struct rhashtable *ht, struct rhash_head *obj,
const struct rhashtable_params params)
{
const char *key = rht_obj(ht, obj);
BUG_ON(ht->p.obj_hashfn);
return __rhashtable_insert_fast(ht, key + ht->p.key_offset, obj, params,
false);
}
/**
* rhashtable_lookup_insert_key - search and insert object to hash table
* with explicit key
* @ht: hash table
* @key: key
* @obj: pointer to hash head inside object
* @params: hash table parameters
*
* Locks down the bucket chain in both the old and new table if a resize
* is in progress to ensure that writers can't remove from the old table
* and can't insert to the new table during the atomic operation of search
* and insertion. Searches for duplicates in both the old and new table if
* a resize is in progress.
*
* Lookups may occur in parallel with hashtable mutations and resizing.
*
* Will trigger an automatic deferred table resizing if the size grows
* beyond the watermark indicated by grow_decision() which can be passed
* to rhashtable_init().
*
* Returns zero on success.
*/
static inline int rhashtable_lookup_insert_key(
struct rhashtable *ht, const void *key, struct rhash_head *obj,
const struct rhashtable_params params)
{
void *ret;
BUG_ON(!ht->p.obj_hashfn || !key);
ret = __rhashtable_insert_fast(ht, key, obj, params, false);
if (IS_ERR(ret))
return PTR_ERR(ret);
return ret == NULL ? 0 : -EEXIST;
}
/**
* rhashtable_lookup_get_insert_key - lookup and insert object into hash table
* @ht: hash table
* @obj: pointer to hash head inside object
* @params: hash table parameters
* @data: pointer to element data already in hashes
*
* Just like rhashtable_lookup_insert_key(), but this function returns the
* object if it exists, NULL if it does not and the insertion was successful,
* and an ERR_PTR otherwise.
*/
static inline void *rhashtable_lookup_get_insert_key(
struct rhashtable *ht, const void *key, struct rhash_head *obj,
const struct rhashtable_params params)
{
BUG_ON(!ht->p.obj_hashfn || !key);
return __rhashtable_insert_fast(ht, key, obj, params, false);
}
/* Internal function, please use rhashtable_remove_fast() instead */
static inline int __rhashtable_remove_fast_one(
struct rhashtable *ht, struct bucket_table *tbl,
struct rhash_head *obj, const struct rhashtable_params params,
bool rhlist)
{
struct rhash_head __rcu **pprev;
struct rhash_head *he;
spinlock_t * lock;
unsigned int hash;
int err = -ENOENT;
hash = rht_head_hashfn(ht, tbl, obj, params);
lock = rht_bucket_lock(tbl, hash);
spin_lock_bh(lock);
pprev = rht_bucket_var(tbl, hash);
rht_for_each_continue(he, *pprev, tbl, hash) {
struct rhlist_head *list;
list = container_of(he, struct rhlist_head, rhead);
if (he != obj) {
struct rhlist_head __rcu **lpprev;
pprev = &he->next;
if (!rhlist)
continue;
do {
lpprev = &list->next;
list = rht_dereference_bucket(list->next,
tbl, hash);
} while (list && obj != &list->rhead);
if (!list)
continue;
list = rht_dereference_bucket(list->next, tbl, hash);
RCU_INIT_POINTER(*lpprev, list);
err = 0;
break;
}
obj = rht_dereference_bucket(obj->next, tbl, hash);
err = 1;
if (rhlist) {
list = rht_dereference_bucket(list->next, tbl, hash);
if (list) {
RCU_INIT_POINTER(list->rhead.next, obj);
obj = &list->rhead;
err = 0;
}
}
rcu_assign_pointer(*pprev, obj);
break;
}
spin_unlock_bh(lock);
if (err > 0) {
atomic_dec(&ht->nelems);
if (unlikely(ht->p.automatic_shrinking &&
rht_shrink_below_30(ht, tbl)))
schedule_work(&ht->run_work);
err = 0;
}
return err;
}
/* Internal function, please use rhashtable_remove_fast() instead */
static inline int __rhashtable_remove_fast(
struct rhashtable *ht, struct rhash_head *obj,
const struct rhashtable_params params, bool rhlist)
{
struct bucket_table *tbl;
int err;
rcu_read_lock();
tbl = rht_dereference_rcu(ht->tbl, ht);
/* Because we have already taken (and released) the bucket
* lock in old_tbl, if we find that future_tbl is not yet
* visible then that guarantees the entry to still be in
* the old tbl if it exists.
*/
while ((err = __rhashtable_remove_fast_one(ht, tbl, obj, params,
rhlist)) &&
(tbl = rht_dereference_rcu(tbl->future_tbl, ht)))
;
rcu_read_unlock();
return err;
}
/**
* rhashtable_remove_fast - remove object from hash table
* @ht: hash table
* @obj: pointer to hash head inside object
* @params: hash table parameters
*
* Since the hash chain is single linked, the removal operation needs to
* walk the bucket chain upon removal. The removal operation is thus
* considerable slow if the hash table is not correctly sized.
*
* Will automatically shrink the table via rhashtable_expand() if the
* shrink_decision function specified at rhashtable_init() returns true.
*
* 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 via rhashtable_expand() if the
* shrink_decision function specified at rhashtable_init() returns true.
*
* Returns zero on success, -ENOENT if the entry could not be found.
*/
static inline int rhltable_remove(
struct rhltable *hlt, struct rhlist_head *list,
const struct rhashtable_params params)
{
return __rhashtable_remove_fast(&hlt->ht, &list->rhead, params, true);
}
/* Internal function, please use rhashtable_replace_fast() instead */
static inline int __rhashtable_replace_fast(
struct rhashtable *ht, struct bucket_table *tbl,
struct rhash_head *obj_old, struct rhash_head *obj_new,
const struct rhashtable_params params)
{
struct rhash_head __rcu **pprev;
struct rhash_head *he;
spinlock_t *lock;
unsigned int hash;
int err = -ENOENT;
/* Minimally, the old and new objects must have same hash
* (which should mean identifiers are the same).
*/
hash = rht_head_hashfn(ht, tbl, obj_old, params);
if (hash != rht_head_hashfn(ht, tbl, obj_new, params))
return -EINVAL;
lock = rht_bucket_lock(tbl, hash);
spin_lock_bh(lock);
pprev = rht_bucket_var(tbl, hash);
rht_for_each_continue(he, *pprev, tbl, hash) {
if (he != obj_old) {
pprev = &he->next;
continue;
}
rcu_assign_pointer(obj_new->next, obj_old->next);
rcu_assign_pointer(*pprev, obj_new);
err = 0;
break;
}
spin_unlock_bh(lock);
return err;
}
/**
* rhashtable_replace_fast - replace an object in hash table
* @ht: hash table
* @obj_old: pointer to hash head inside object being replaced
* @obj_new: pointer to hash head inside object which is new
* @params: hash table parameters
*
* Replacing an object doesn't affect the number of elements in the hash table
* or bucket, so we don't need to worry about shrinking or expanding the
* table here.
*
* Returns zero on success, -ENOENT if the entry could not be found,
* -EINVAL if hash is not the same for the old and new objects.
*/
static inline int rhashtable_replace_fast(
struct rhashtable *ht, struct rhash_head *obj_old,
struct rhash_head *obj_new,
const struct rhashtable_params params)
{
struct bucket_table *tbl;
int err;
rcu_read_lock();
tbl = rht_dereference_rcu(ht->tbl, ht);
/* Because we have already taken (and released) the bucket
* lock in old_tbl, if we find that future_tbl is not yet
* visible then that guarantees the entry to still be in
* the old tbl if it exists.
*/
while ((err = __rhashtable_replace_fast(ht, tbl, obj_old,
obj_new, params)) &&
(tbl = rht_dereference_rcu(tbl->future_tbl, ht)))
;
rcu_read_unlock();
return err;
}
/* Obsolete function, do not use in new code. */
static inline int rhashtable_walk_init(struct rhashtable *ht,
struct rhashtable_iter *iter, gfp_t gfp)
{
rhashtable_walk_enter(ht, iter);
return 0;
}
/**
* rhltable_walk_enter - Initialise an iterator
* @hlt: Table to walk over
* @iter: Hash table Iterator
*
* This function prepares a hash table walk.
*
* Note that if you restart a walk after rhashtable_walk_stop you
* may see the same object twice. Also, you may miss objects if
* there are removals in between rhashtable_walk_stop and the next
* call to rhashtable_walk_start.
*
* For a completely stable walk you should construct your own data
* structure outside the hash table.
*
* This function may sleep so you must not call it from interrupt
* context or with spin locks held.
*
* 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 */
