v4.19.13 snapshot.
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
new file mode 100644
index 0000000..eb71110
--- /dev/null
+++ b/include/linux/rhashtable.h
@@ -0,0 +1,1154 @@
+/* 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/rhashtable-types.h>
+/*
+ * The end of the chain is marked with a special nulls marks which has
+ * the least significant bit set.
+ */
+
+/* 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
+ * @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;
+};
+
+#define INIT_RHT_NULLS_HEAD(ptr) \
+ ((ptr) = (typeof(ptr)) NULLS_MARKER(0))
+
+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;
+}
+
+/* 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 */
+
+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_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(rcu_access_pointer(tbl->future_tbl))) {
+slow_path:
+ spin_unlock_bh(lock);
+ rcu_read_unlock();
+ return rhashtable_insert_slow(ht, key, obj);
+ }
+
+ elasticity = RHT_ELASTICITY;
+ pprev = rht_bucket_insert(ht, tbl, hash);
+ data = ERR_PTR(-ENOMEM);
+ if (!pprev)
+ goto out;
+
+ rht_for_each_continue(head, *pprev, tbl, hash) {
+ struct rhlist_head *plist;
+ struct rhlist_head *list;
+
+ elasticity--;
+ if (!key ||
+ (params.obj_cmpfn ?
+ params.obj_cmpfn(&arg, rht_obj(ht, head)) :
+ rhashtable_compare(&arg, rht_obj(ht, head)))) {
+ pprev = &head->next;
+ continue;
+ }
+
+ data = rht_obj(ht, head);
+
+ if (!rhlist)
+ goto out;
+
+
+ list = container_of(obj, struct rhlist_head, rhead);
+ plist = container_of(head, struct rhlist_head, rhead);
+
+ RCU_INIT_POINTER(list->next, plist);
+ head = rht_dereference_bucket(head->next, tbl, hash);
+ RCU_INIT_POINTER(list->rhead.next, head);
+ rcu_assign_pointer(*pprev, obj);
+
+ goto good;
+ }
+
+ if (elasticity <= 0)
+ goto slow_path;
+
+ data = ERR_PTR(-E2BIG);
+ if (unlikely(rht_grow_above_max(ht, tbl)))
+ goto out;
+
+ if (unlikely(rht_grow_above_100(ht, tbl)))
+ goto slow_path;
+
+ head = rht_dereference_bucket(*pprev, tbl, hash);
+
+ RCU_INIT_POINTER(obj->next, head);
+ if (rhlist) {
+ struct rhlist_head *list;
+
+ list = container_of(obj, struct rhlist_head, rhead);
+ RCU_INIT_POINTER(list->next, NULL);
+ }
+
+ rcu_assign_pointer(*pprev, obj);
+
+ atomic_inc(&ht->nelems);
+ if (rht_grow_above_75(ht, tbl))
+ schedule_work(&ht->run_work);
+
+good:
+ data = NULL;
+
+out:
+ spin_unlock_bh(lock);
+ rcu_read_unlock();
+
+ return data;
+}
+
+/**
+ * rhashtable_insert_fast - insert object into hash table
+ * @ht: hash table
+ * @obj: pointer to hash head inside object
+ * @params: hash table parameters
+ *
+ * Will take a per bucket spinlock to protect against mutual mutations
+ * on the same bucket. Multiple insertions may occur in parallel unless
+ * they map to the same bucket lock.
+ *
+ * It is safe to call this function from atomic context.
+ *
+ * Will trigger an automatic deferred table resizing if residency in the
+ * table grows beyond 70%.
+ */
+static inline int rhashtable_insert_fast(
+ struct rhashtable *ht, struct rhash_head *obj,
+ const struct rhashtable_params params)
+{
+ void *ret;
+
+ ret = __rhashtable_insert_fast(ht, NULL, obj, params, false);
+ if (IS_ERR(ret))
+ return PTR_ERR(ret);
+
+ return ret == NULL ? 0 : -EEXIST;
+}
+
+/**
+ * rhltable_insert_key - insert object into hash list table
+ * @hlt: hash list table
+ * @key: the pointer to the key
+ * @list: pointer to hash list head inside object
+ * @params: hash table parameters
+ *
+ * Will take a per bucket spinlock to protect against mutual mutations
+ * on the same bucket. Multiple insertions may occur in parallel unless
+ * they map to the same bucket lock.
+ *
+ * It is safe to call this function from atomic context.
+ *
+ * Will trigger an automatic deferred table resizing if residency in the
+ * table grows beyond 70%.
+ */
+static inline int rhltable_insert_key(
+ struct rhltable *hlt, const void *key, struct rhlist_head *list,
+ const struct rhashtable_params params)
+{
+ return PTR_ERR(__rhashtable_insert_fast(&hlt->ht, key, &list->rhead,
+ params, true));
+}
+
+/**
+ * rhltable_insert - insert object into hash list table
+ * @hlt: hash list table
+ * @list: pointer to hash list head inside object
+ * @params: hash table parameters
+ *
+ * Will take a per bucket spinlock to protect against mutual mutations
+ * on the same bucket. Multiple insertions may occur in parallel unless
+ * they map to the same bucket lock.
+ *
+ * It is safe to call this function from atomic context.
+ *
+ * Will trigger an automatic deferred table resizing if residency in the
+ * table grows beyond 70%.
+ */
+static inline int rhltable_insert(
+ struct rhltable *hlt, struct rhlist_head *list,
+ const struct rhashtable_params params)
+{
+ const char *key = rht_obj(&hlt->ht, &list->rhead);
+
+ key += params.key_offset;
+
+ return rhltable_insert_key(hlt, key, list, params);
+}
+
+/**
+ * rhashtable_lookup_insert_fast - lookup and insert object into hash table
+ * @ht: hash table
+ * @obj: pointer to hash head inside object
+ * @params: hash table parameters
+ *
+ * Locks down the bucket chain in both the old and new table if a resize
+ * is in progress to ensure that writers can't remove from the old table
+ * and can't insert to the new table during the atomic operation of search
+ * and insertion. Searches for duplicates in both the old and new table if
+ * a resize is in progress.
+ *
+ * This lookup function may only be used for fixed key hash table (key_len
+ * parameter set). It will BUG() if used inappropriately.
+ *
+ * It is safe to call this function from atomic context.
+ *
+ * Will trigger an automatic deferred table resizing if residency in the
+ * table grows beyond 70%.
+ */
+static inline int rhashtable_lookup_insert_fast(
+ struct rhashtable *ht, struct rhash_head *obj,
+ const struct rhashtable_params params)
+{
+ const char *key = rht_obj(ht, obj);
+ void *ret;
+
+ BUG_ON(ht->p.obj_hashfn);
+
+ ret = __rhashtable_insert_fast(ht, key + ht->p.key_offset, obj, params,
+ false);
+ if (IS_ERR(ret))
+ return PTR_ERR(ret);
+
+ return ret == NULL ? 0 : -EEXIST;
+}
+
+/**
+ * rhashtable_lookup_get_insert_fast - lookup and insert object into hash table
+ * @ht: hash table
+ * @obj: pointer to hash head inside object
+ * @params: hash table parameters
+ *
+ * Just like rhashtable_lookup_insert_fast(), but this function returns the
+ * object if it exists, NULL if it did not and the insertion was successful,
+ * and an ERR_PTR otherwise.
+ */
+static inline void *rhashtable_lookup_get_insert_fast(
+ struct rhashtable *ht, struct rhash_head *obj,
+ const struct rhashtable_params params)
+{
+ const char *key = rht_obj(ht, obj);
+
+ BUG_ON(ht->p.obj_hashfn);
+
+ return __rhashtable_insert_fast(ht, key + ht->p.key_offset, obj, params,
+ false);
+}
+
+/**
+ * rhashtable_lookup_insert_key - search and insert object to hash table
+ * with explicit key
+ * @ht: hash table
+ * @key: key
+ * @obj: pointer to hash head inside object
+ * @params: hash table parameters
+ *
+ * Locks down the bucket chain in both the old and new table if a resize
+ * is in progress to ensure that writers can't remove from the old table
+ * and can't insert to the new table during the atomic operation of search
+ * and insertion. Searches for duplicates in both the old and new table if
+ * a resize is in progress.
+ *
+ * Lookups may occur in parallel with hashtable mutations and resizing.
+ *
+ * Will trigger an automatic deferred table resizing if residency in the
+ * table grows beyond 70%.
+ *
+ * Returns zero on success.
+ */
+static inline int rhashtable_lookup_insert_key(
+ struct rhashtable *ht, const void *key, struct rhash_head *obj,
+ const struct rhashtable_params params)
+{
+ void *ret;
+
+ BUG_ON(!ht->p.obj_hashfn || !key);
+
+ ret = __rhashtable_insert_fast(ht, key, obj, params, false);
+ if (IS_ERR(ret))
+ return PTR_ERR(ret);
+
+ return ret == NULL ? 0 : -EEXIST;
+}
+
+/**
+ * rhashtable_lookup_get_insert_key - lookup and insert object into hash table
+ * @ht: hash table
+ * @obj: pointer to hash head inside object
+ * @params: hash table parameters
+ * @data: pointer to element data already in hashes
+ *
+ * Just like rhashtable_lookup_insert_key(), but this function returns the
+ * object if it exists, NULL if it does not and the insertion was successful,
+ * and an ERR_PTR otherwise.
+ */
+static inline void *rhashtable_lookup_get_insert_key(
+ struct rhashtable *ht, const void *key, struct rhash_head *obj,
+ const struct rhashtable_params params)
+{
+ BUG_ON(!ht->p.obj_hashfn || !key);
+
+ return __rhashtable_insert_fast(ht, key, obj, params, false);
+}
+
+/* Internal function, please use rhashtable_remove_fast() instead */
+static inline int __rhashtable_remove_fast_one(
+ struct rhashtable *ht, struct bucket_table *tbl,
+ struct rhash_head *obj, const struct rhashtable_params params,
+ bool rhlist)
+{
+ struct rhash_head __rcu **pprev;
+ struct rhash_head *he;
+ spinlock_t * lock;
+ unsigned int hash;
+ int err = -ENOENT;
+
+ hash = rht_head_hashfn(ht, tbl, obj, params);
+ lock = rht_bucket_lock(tbl, hash);
+
+ spin_lock_bh(lock);
+
+ pprev = rht_bucket_var(tbl, hash);
+ rht_for_each_continue(he, *pprev, tbl, hash) {
+ struct rhlist_head *list;
+
+ list = container_of(he, struct rhlist_head, rhead);
+
+ if (he != obj) {
+ struct rhlist_head __rcu **lpprev;
+
+ pprev = &he->next;
+
+ if (!rhlist)
+ continue;
+
+ do {
+ lpprev = &list->next;
+ list = rht_dereference_bucket(list->next,
+ tbl, hash);
+ } while (list && obj != &list->rhead);
+
+ if (!list)
+ continue;
+
+ list = rht_dereference_bucket(list->next, tbl, hash);
+ RCU_INIT_POINTER(*lpprev, list);
+ err = 0;
+ break;
+ }
+
+ obj = rht_dereference_bucket(obj->next, tbl, hash);
+ err = 1;
+
+ if (rhlist) {
+ list = rht_dereference_bucket(list->next, tbl, hash);
+ if (list) {
+ RCU_INIT_POINTER(list->rhead.next, obj);
+ obj = &list->rhead;
+ err = 0;
+ }
+ }
+
+ rcu_assign_pointer(*pprev, obj);
+ break;
+ }
+
+ spin_unlock_bh(lock);
+
+ if (err > 0) {
+ atomic_dec(&ht->nelems);
+ if (unlikely(ht->p.automatic_shrinking &&
+ rht_shrink_below_30(ht, tbl)))
+ schedule_work(&ht->run_work);
+ err = 0;
+ }
+
+ return err;
+}
+
+/* Internal function, please use rhashtable_remove_fast() instead */
+static inline int __rhashtable_remove_fast(
+ struct rhashtable *ht, struct rhash_head *obj,
+ const struct rhashtable_params params, bool rhlist)
+{
+ struct bucket_table *tbl;
+ int err;
+
+ rcu_read_lock();
+
+ tbl = rht_dereference_rcu(ht->tbl, ht);
+
+ /* Because we have already taken (and released) the bucket
+ * lock in old_tbl, if we find that future_tbl is not yet
+ * visible then that guarantees the entry to still be in
+ * the old tbl if it exists.
+ */
+ while ((err = __rhashtable_remove_fast_one(ht, tbl, obj, params,
+ rhlist)) &&
+ (tbl = rht_dereference_rcu(tbl->future_tbl, ht)))
+ ;
+
+ rcu_read_unlock();
+
+ return err;
+}
+
+/**
+ * rhashtable_remove_fast - remove object from hash table
+ * @ht: hash table
+ * @obj: pointer to hash head inside object
+ * @params: hash table parameters
+ *
+ * Since the hash chain is single linked, the removal operation needs to
+ * walk the bucket chain upon removal. The removal operation is thus
+ * considerable slow if the hash table is not correctly sized.
+ *
+ * Will automatically shrink the table if permitted when residency drops
+ * below 30%.
+ *
+ * Returns zero on success, -ENOENT if the entry could not be found.
+ */
+static inline int rhashtable_remove_fast(
+ struct rhashtable *ht, struct rhash_head *obj,
+ const struct rhashtable_params params)
+{
+ return __rhashtable_remove_fast(ht, obj, params, false);
+}
+
+/**
+ * rhltable_remove - remove object from hash list table
+ * @hlt: hash list table
+ * @list: pointer to hash list head inside object
+ * @params: hash table parameters
+ *
+ * Since the hash chain is single linked, the removal operation needs to
+ * walk the bucket chain upon removal. The removal operation is thus
+ * considerable slow if the hash table is not correctly sized.
+ *
+ * Will automatically shrink the table if permitted when residency drops
+ * below 30%
+ *
+ * Returns zero on success, -ENOENT if the entry could not be found.
+ */
+static inline int rhltable_remove(
+ struct rhltable *hlt, struct rhlist_head *list,
+ const struct rhashtable_params params)
+{
+ return __rhashtable_remove_fast(&hlt->ht, &list->rhead, params, true);
+}
+
+/* Internal function, please use rhashtable_replace_fast() instead */
+static inline int __rhashtable_replace_fast(
+ struct rhashtable *ht, struct bucket_table *tbl,
+ struct rhash_head *obj_old, struct rhash_head *obj_new,
+ const struct rhashtable_params params)
+{
+ struct rhash_head __rcu **pprev;
+ struct rhash_head *he;
+ spinlock_t *lock;
+ unsigned int hash;
+ int err = -ENOENT;
+
+ /* Minimally, the old and new objects must have same hash
+ * (which should mean identifiers are the same).
+ */
+ hash = rht_head_hashfn(ht, tbl, obj_old, params);
+ if (hash != rht_head_hashfn(ht, tbl, obj_new, params))
+ return -EINVAL;
+
+ lock = rht_bucket_lock(tbl, hash);
+
+ spin_lock_bh(lock);
+
+ pprev = rht_bucket_var(tbl, hash);
+ rht_for_each_continue(he, *pprev, tbl, hash) {
+ if (he != obj_old) {
+ pprev = &he->next;
+ continue;
+ }
+
+ rcu_assign_pointer(obj_new->next, obj_old->next);
+ rcu_assign_pointer(*pprev, obj_new);
+ err = 0;
+ break;
+ }
+
+ spin_unlock_bh(lock);
+
+ return err;
+}
+
+/**
+ * rhashtable_replace_fast - replace an object in hash table
+ * @ht: hash table
+ * @obj_old: pointer to hash head inside object being replaced
+ * @obj_new: pointer to hash head inside object which is new
+ * @params: hash table parameters
+ *
+ * Replacing an object doesn't affect the number of elements in the hash table
+ * or bucket, so we don't need to worry about shrinking or expanding the
+ * table here.
+ *
+ * Returns zero on success, -ENOENT if the entry could not be found,
+ * -EINVAL if hash is not the same for the old and new objects.
+ */
+static inline int rhashtable_replace_fast(
+ struct rhashtable *ht, struct rhash_head *obj_old,
+ struct rhash_head *obj_new,
+ const struct rhashtable_params params)
+{
+ struct bucket_table *tbl;
+ int err;
+
+ rcu_read_lock();
+
+ tbl = rht_dereference_rcu(ht->tbl, ht);
+
+ /* Because we have already taken (and released) the bucket
+ * lock in old_tbl, if we find that future_tbl is not yet
+ * visible then that guarantees the entry to still be in
+ * the old tbl if it exists.
+ */
+ while ((err = __rhashtable_replace_fast(ht, tbl, obj_old,
+ obj_new, params)) &&
+ (tbl = rht_dereference_rcu(tbl->future_tbl, ht)))
+ ;
+
+ rcu_read_unlock();
+
+ return err;
+}
+
+/* Obsolete function, do not use in new code. */
+static inline int rhashtable_walk_init(struct rhashtable *ht,
+ struct rhashtable_iter *iter, gfp_t gfp)
+{
+ rhashtable_walk_enter(ht, iter);
+ return 0;
+}
+
+/**
+ * rhltable_walk_enter - Initialise an iterator
+ * @hlt: Table to walk over
+ * @iter: Hash table Iterator
+ *
+ * This function prepares a hash table walk.
+ *
+ * Note that if you restart a walk after rhashtable_walk_stop you
+ * may see the same object twice. Also, you may miss objects if
+ * there are removals in between rhashtable_walk_stop and the next
+ * call to rhashtable_walk_start.
+ *
+ * For a completely stable walk you should construct your own data
+ * structure outside the hash table.
+ *
+ * This function may be called from any process context, including
+ * non-preemptable context, but cannot be called from softirq or
+ * hardirq context.
+ *
+ * You must call rhashtable_walk_exit after this function returns.
+ */
+static inline void rhltable_walk_enter(struct rhltable *hlt,
+ struct rhashtable_iter *iter)
+{
+ return rhashtable_walk_enter(&hlt->ht, iter);
+}
+
+/**
+ * rhltable_free_and_destroy - free elements and destroy hash list table
+ * @hlt: the hash list table to destroy
+ * @free_fn: callback to release resources of element
+ * @arg: pointer passed to free_fn
+ *
+ * See documentation for rhashtable_free_and_destroy.
+ */
+static inline void rhltable_free_and_destroy(struct rhltable *hlt,
+ void (*free_fn)(void *ptr,
+ void *arg),
+ void *arg)
+{
+ return rhashtable_free_and_destroy(&hlt->ht, free_fn, arg);
+}
+
+static inline void rhltable_destroy(struct rhltable *hlt)
+{
+ return rhltable_free_and_destroy(hlt, NULL, NULL);
+}
+
+#endif /* _LINUX_RHASHTABLE_H */