+++ /dev/null
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * Resizable, Scalable, Concurrent Hash Table
- *
- * Copyright (c) 2015 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
- */
-
-#include <linux/atomic.h>
-#include <linux/kernel.h>
-#include <linux/log2.h>
-#include <linux/sched.h>
-#include <linux/rculist.h>
-#include <linux/slab.h>
-#include <linux/vmalloc.h>
-#include <linux/jhash.h>
-#include <linux/overflow.h>
-#include <linux/random.h>
-#include <linux/rhashtable.h>
-#include <linux/err.h>
-#include <linux/export.h>
-
-#define HASH_DEFAULT_SIZE 64UL
-#define HASH_MIN_SIZE 4U
-
-union nested_table {
- union nested_table __rcu *table;
- struct rhash_lock_head __rcu *bucket;
-};
-
-static u32 head_hashfn(struct rhashtable *ht,
- const struct bucket_table *tbl,
- const struct rhash_head *he)
-{
- return rht_head_hashfn(ht, tbl, he, ht->p);
-}
-
-#ifdef CONFIG_PROVE_LOCKING
-#define ASSERT_RHT_MUTEX(HT) BUG_ON(!lockdep_rht_mutex_is_held(HT))
-
-int lockdep_rht_mutex_is_held(struct rhashtable *ht)
-{
- return (debug_locks) ? lockdep_is_held(&ht->mutex) : 1;
-}
-EXPORT_SYMBOL_GPL(lockdep_rht_mutex_is_held);
-
-int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash)
-{
- if (!debug_locks)
- return 1;
- if (unlikely(tbl->nest))
- return 1;
- return bit_spin_is_locked(0, (unsigned long *)&tbl->buckets[hash]);
-}
-EXPORT_SYMBOL_GPL(lockdep_rht_bucket_is_held);
-#else
-#define ASSERT_RHT_MUTEX(HT)
-#endif
-
-static inline union nested_table *nested_table_top(
- const struct bucket_table *tbl)
-{
- /* The top-level bucket entry does not need RCU protection
- * because it's set at the same time as tbl->nest.
- */
- return (void *)rcu_dereference_protected(tbl->buckets[0], 1);
-}
-
-static void nested_table_free(union nested_table *ntbl, unsigned int size)
-{
- const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *));
- const unsigned int len = 1 << shift;
- unsigned int i;
-
- ntbl = rcu_dereference_protected(ntbl->table, 1);
- if (!ntbl)
- return;
-
- if (size > len) {
- size >>= shift;
- for (i = 0; i < len; i++)
- nested_table_free(ntbl + i, size);
- }
-
- kfree(ntbl);
-}
-
-static void nested_bucket_table_free(const struct bucket_table *tbl)
-{
- unsigned int size = tbl->size >> tbl->nest;
- unsigned int len = 1 << tbl->nest;
- union nested_table *ntbl;
- unsigned int i;
-
- ntbl = nested_table_top(tbl);
-
- for (i = 0; i < len; i++)
- nested_table_free(ntbl + i, size);
-
- kfree(ntbl);
-}
-
-static void bucket_table_free(struct bucket_table *tbl)
-{
- if (tbl->nest)
- nested_bucket_table_free(tbl);
-
- kvfree(tbl);
-}
-
-static void bucket_table_free_rcu(struct rcu_head *head)
-{
- bucket_table_free(container_of(head, struct bucket_table, rcu));
-}
-
-static union nested_table *nested_table_alloc(struct rhashtable *ht,
- union nested_table __rcu **prev,
- bool leaf)
-{
- union nested_table *ntbl;
- int i;
-
- ntbl = rcu_dereference(*prev);
- if (ntbl)
- return ntbl;
-
- ntbl = kzalloc(PAGE_SIZE, GFP_ATOMIC);
-
- if (ntbl && leaf) {
- for (i = 0; i < PAGE_SIZE / sizeof(ntbl[0]); i++)
- INIT_RHT_NULLS_HEAD(ntbl[i].bucket);
- }
-
- if (cmpxchg((union nested_table **)prev, NULL, ntbl) == NULL)
- return ntbl;
- /* Raced with another thread. */
- kfree(ntbl);
- return rcu_dereference(*prev);
-}
-
-static struct bucket_table *nested_bucket_table_alloc(struct rhashtable *ht,
- size_t nbuckets,
- gfp_t gfp)
-{
- const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *));
- struct bucket_table *tbl;
- size_t size;
-
- if (nbuckets < (1 << (shift + 1)))
- return NULL;
-
- size = sizeof(*tbl) + sizeof(tbl->buckets[0]);
-
- tbl = kzalloc(size, gfp);
- if (!tbl)
- return NULL;
-
- if (!nested_table_alloc(ht, (union nested_table __rcu **)tbl->buckets,
- false)) {
- kfree(tbl);
- return NULL;
- }
-
- tbl->nest = (ilog2(nbuckets) - 1) % shift + 1;
-
- return tbl;
-}
-
-static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
- size_t nbuckets,
- gfp_t gfp)
-{
- struct bucket_table *tbl = NULL;
- size_t size;
- int i;
-
- tbl = kvzalloc(struct_size(tbl, buckets, nbuckets), gfp);
-
- size = nbuckets;
-
- if (tbl == NULL && (gfp & ~__GFP_NOFAIL) != GFP_KERNEL) {
- tbl = nested_bucket_table_alloc(ht, nbuckets, gfp);
- nbuckets = 0;
- }
-
- if (tbl == NULL)
- return NULL;
-
- tbl->size = size;
-
- rcu_head_init(&tbl->rcu);
- INIT_LIST_HEAD(&tbl->walkers);
-
- tbl->hash_rnd = get_random_u32();
-
- for (i = 0; i < nbuckets; i++)
- INIT_RHT_NULLS_HEAD(tbl->buckets[i]);
-
- return tbl;
-}
-
-static struct bucket_table *rhashtable_last_table(struct rhashtable *ht,
- struct bucket_table *tbl)
-{
- struct bucket_table *new_tbl;
-
- do {
- new_tbl = tbl;
- tbl = rht_dereference_rcu(tbl->future_tbl, ht);
- } while (tbl);
-
- return new_tbl;
-}
-
-static int rhashtable_rehash_one(struct rhashtable *ht,
- struct rhash_lock_head __rcu **bkt,
- unsigned int old_hash)
-{
- struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
- struct bucket_table *new_tbl = rhashtable_last_table(ht, old_tbl);
- int err = -EAGAIN;
- struct rhash_head *head, *next, *entry;
- struct rhash_head __rcu **pprev = NULL;
- unsigned int new_hash;
-
- if (new_tbl->nest)
- goto out;
-
- err = -ENOENT;
-
- rht_for_each_from(entry, rht_ptr(bkt, old_tbl, old_hash),
- old_tbl, old_hash) {
- err = 0;
- next = rht_dereference_bucket(entry->next, old_tbl, old_hash);
-
- if (rht_is_a_nulls(next))
- break;
-
- pprev = &entry->next;
- }
-
- if (err)
- goto out;
-
- new_hash = head_hashfn(ht, new_tbl, entry);
-
- rht_lock(new_tbl, &new_tbl->buckets[new_hash]);
-
- head = rht_ptr(new_tbl->buckets + new_hash, new_tbl, new_hash);
-
- RCU_INIT_POINTER(entry->next, head);
-
- rht_assign_unlock(new_tbl, &new_tbl->buckets[new_hash], entry);
-
- if (pprev)
- rcu_assign_pointer(*pprev, next);
- else
- /* Need to preserved the bit lock. */
- rht_assign_locked(bkt, next);
-
-out:
- return err;
-}
-
-static int rhashtable_rehash_chain(struct rhashtable *ht,
- unsigned int old_hash)
-{
- struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
- struct rhash_lock_head __rcu **bkt = rht_bucket_var(old_tbl, old_hash);
- int err;
-
- if (!bkt)
- return 0;
- rht_lock(old_tbl, bkt);
-
- while (!(err = rhashtable_rehash_one(ht, bkt, old_hash)))
- ;
-
- if (err == -ENOENT)
- err = 0;
- rht_unlock(old_tbl, bkt);
-
- return err;
-}
-
-static int rhashtable_rehash_attach(struct rhashtable *ht,
- struct bucket_table *old_tbl,
- struct bucket_table *new_tbl)
-{
- /* Make insertions go into the new, empty table right away. Deletions
- * and lookups will be attempted in both tables until we synchronize.
- * As cmpxchg() provides strong barriers, we do not need
- * rcu_assign_pointer().
- */
-
- if (cmpxchg((struct bucket_table **)&old_tbl->future_tbl, NULL,
- new_tbl) != NULL)
- return -EEXIST;
-
- return 0;
-}
-
-static int rhashtable_rehash_table(struct rhashtable *ht)
-{
- struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
- struct bucket_table *new_tbl;
- struct rhashtable_walker *walker;
- unsigned int old_hash;
- int err;
-
- new_tbl = rht_dereference(old_tbl->future_tbl, ht);
- if (!new_tbl)
- return 0;
-
- for (old_hash = 0; old_hash < old_tbl->size; old_hash++) {
- err = rhashtable_rehash_chain(ht, old_hash);
- if (err)
- return err;
- cond_resched();
- }
-
- /* Publish the new table pointer. */
- rcu_assign_pointer(ht->tbl, new_tbl);
-
- spin_lock(&ht->lock);
- list_for_each_entry(walker, &old_tbl->walkers, list)
- walker->tbl = NULL;
-
- /* Wait for readers. All new readers will see the new
- * table, and thus no references to the old table will
- * remain.
- * We do this inside the locked region so that
- * rhashtable_walk_stop() can use rcu_head_after_call_rcu()
- * to check if it should not re-link the table.
- */
- call_rcu(&old_tbl->rcu, bucket_table_free_rcu);
- spin_unlock(&ht->lock);
-
- return rht_dereference(new_tbl->future_tbl, ht) ? -EAGAIN : 0;
-}
-
-static int rhashtable_rehash_alloc(struct rhashtable *ht,
- struct bucket_table *old_tbl,
- unsigned int size)
-{
- struct bucket_table *new_tbl;
- int err;
-
- ASSERT_RHT_MUTEX(ht);
-
- new_tbl = bucket_table_alloc(ht, size, GFP_KERNEL);
- if (new_tbl == NULL)
- return -ENOMEM;
-
- err = rhashtable_rehash_attach(ht, old_tbl, new_tbl);
- if (err)
- bucket_table_free(new_tbl);
-
- return err;
-}
-
-/**
- * rhashtable_shrink - Shrink hash table while allowing concurrent lookups
- * @ht: the hash table to shrink
- *
- * This function shrinks the hash table to fit, i.e., the smallest
- * size would not cause it to expand right away automatically.
- *
- * The caller must ensure that no concurrent resizing occurs by holding
- * ht->mutex.
- *
- * The caller must ensure that no concurrent table mutations take place.
- * It is however valid to have concurrent lookups if they are RCU protected.
- *
- * It is valid to have concurrent insertions and deletions protected by per
- * bucket locks or concurrent RCU protected lookups and traversals.
- */
-static int rhashtable_shrink(struct rhashtable *ht)
-{
- struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
- unsigned int nelems = atomic_read(&ht->nelems);
- unsigned int size = 0;
-
- if (nelems)
- size = roundup_pow_of_two(nelems * 3 / 2);
- if (size < ht->p.min_size)
- size = ht->p.min_size;
-
- if (old_tbl->size <= size)
- return 0;
-
- if (rht_dereference(old_tbl->future_tbl, ht))
- return -EEXIST;
-
- return rhashtable_rehash_alloc(ht, old_tbl, size);
-}
-
-static void rht_deferred_worker(struct work_struct *work)
-{
- struct rhashtable *ht;
- struct bucket_table *tbl;
- int err = 0;
-
- ht = container_of(work, struct rhashtable, run_work);
- mutex_lock(&ht->mutex);
-
- tbl = rht_dereference(ht->tbl, ht);
- tbl = rhashtable_last_table(ht, tbl);
-
- if (rht_grow_above_75(ht, tbl))
- err = rhashtable_rehash_alloc(ht, tbl, tbl->size * 2);
- else if (ht->p.automatic_shrinking && rht_shrink_below_30(ht, tbl))
- err = rhashtable_shrink(ht);
- else if (tbl->nest)
- err = rhashtable_rehash_alloc(ht, tbl, tbl->size);
-
- if (!err || err == -EEXIST) {
- int nerr;
-
- nerr = rhashtable_rehash_table(ht);
- err = err ?: nerr;
- }
-
- mutex_unlock(&ht->mutex);
-
- if (err)
- schedule_work(&ht->run_work);
-}
-
-static int rhashtable_insert_rehash(struct rhashtable *ht,
- struct bucket_table *tbl)
-{
- struct bucket_table *old_tbl;
- struct bucket_table *new_tbl;
- unsigned int size;
- int err;
-
- old_tbl = rht_dereference_rcu(ht->tbl, ht);
-
- size = tbl->size;
-
- err = -EBUSY;
-
- if (rht_grow_above_75(ht, tbl))
- size *= 2;
- /* Do not schedule more than one rehash */
- else if (old_tbl != tbl)
- goto fail;
-
- err = -ENOMEM;
-
- new_tbl = bucket_table_alloc(ht, size, GFP_ATOMIC | __GFP_NOWARN);
- if (new_tbl == NULL)
- goto fail;
-
- err = rhashtable_rehash_attach(ht, tbl, new_tbl);
- if (err) {
- bucket_table_free(new_tbl);
- if (err == -EEXIST)
- err = 0;
- } else
- schedule_work(&ht->run_work);
-
- return err;
-
-fail:
- /* Do not fail the insert if someone else did a rehash. */
- if (likely(rcu_access_pointer(tbl->future_tbl)))
- return 0;
-
- /* Schedule async rehash to retry allocation in process context. */
- if (err == -ENOMEM)
- schedule_work(&ht->run_work);
-
- return err;
-}
-
-static void *rhashtable_lookup_one(struct rhashtable *ht,
- struct rhash_lock_head __rcu **bkt,
- struct bucket_table *tbl, unsigned int hash,
- const void *key, struct rhash_head *obj)
-{
- struct rhashtable_compare_arg arg = {
- .ht = ht,
- .key = key,
- };
- struct rhash_head __rcu **pprev = NULL;
- struct rhash_head *head;
- int elasticity;
-
- elasticity = RHT_ELASTICITY;
- rht_for_each_from(head, rht_ptr(bkt, tbl, hash), tbl, hash) {
- struct rhlist_head *list;
- struct rhlist_head *plist;
-
- elasticity--;
- if (!key ||
- (ht->p.obj_cmpfn ?
- ht->p.obj_cmpfn(&arg, rht_obj(ht, head)) :
- rhashtable_compare(&arg, rht_obj(ht, head)))) {
- pprev = &head->next;
- continue;
- }
-
- if (!ht->rhlist)
- return rht_obj(ht, head);
-
- 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);
- else
- /* Need to preserve the bit lock */
- rht_assign_locked(bkt, obj);
-
- return NULL;
- }
-
- if (elasticity <= 0)
- return ERR_PTR(-EAGAIN);
-
- return ERR_PTR(-ENOENT);
-}
-
-static struct bucket_table *rhashtable_insert_one(
- struct rhashtable *ht, struct rhash_lock_head __rcu **bkt,
- struct bucket_table *tbl, unsigned int hash, struct rhash_head *obj,
- void *data)
-{
- struct bucket_table *new_tbl;
- struct rhash_head *head;
-
- if (!IS_ERR_OR_NULL(data))
- return ERR_PTR(-EEXIST);
-
- if (PTR_ERR(data) != -EAGAIN && PTR_ERR(data) != -ENOENT)
- return ERR_CAST(data);
-
- new_tbl = rht_dereference_rcu(tbl->future_tbl, ht);
- if (new_tbl)
- return new_tbl;
-
- if (PTR_ERR(data) != -ENOENT)
- return ERR_CAST(data);
-
- if (unlikely(rht_grow_above_max(ht, tbl)))
- return ERR_PTR(-E2BIG);
-
- if (unlikely(rht_grow_above_100(ht, tbl)))
- return ERR_PTR(-EAGAIN);
-
- head = rht_ptr(bkt, tbl, hash);
-
- RCU_INIT_POINTER(obj->next, head);
- if (ht->rhlist) {
- struct rhlist_head *list;
-
- list = container_of(obj, struct rhlist_head, rhead);
- RCU_INIT_POINTER(list->next, NULL);
- }
-
- /* bkt is always the head of the list, so it holds
- * the lock, which we need to preserve
- */
- rht_assign_locked(bkt, obj);
-
- atomic_inc(&ht->nelems);
- if (rht_grow_above_75(ht, tbl))
- schedule_work(&ht->run_work);
-
- return NULL;
-}
-
-static void *rhashtable_try_insert(struct rhashtable *ht, const void *key,
- struct rhash_head *obj)
-{
- struct bucket_table *new_tbl;
- struct bucket_table *tbl;
- struct rhash_lock_head __rcu **bkt;
- unsigned int hash;
- void *data;
-
- new_tbl = rcu_dereference(ht->tbl);
-
- do {
- tbl = new_tbl;
- hash = rht_head_hashfn(ht, tbl, obj, ht->p);
- if (rcu_access_pointer(tbl->future_tbl))
- /* Failure is OK */
- bkt = rht_bucket_var(tbl, hash);
- else
- bkt = rht_bucket_insert(ht, tbl, hash);
- if (bkt == NULL) {
- new_tbl = rht_dereference_rcu(tbl->future_tbl, ht);
- data = ERR_PTR(-EAGAIN);
- } else {
- rht_lock(tbl, bkt);
- data = rhashtable_lookup_one(ht, bkt, tbl,
- hash, key, obj);
- new_tbl = rhashtable_insert_one(ht, bkt, tbl,
- hash, obj, data);
- if (PTR_ERR(new_tbl) != -EEXIST)
- data = ERR_CAST(new_tbl);
-
- rht_unlock(tbl, bkt);
- }
- } while (!IS_ERR_OR_NULL(new_tbl));
-
- if (PTR_ERR(data) == -EAGAIN)
- data = ERR_PTR(rhashtable_insert_rehash(ht, tbl) ?:
- -EAGAIN);
-
- return data;
-}
-
-void *rhashtable_insert_slow(struct rhashtable *ht, const void *key,
- struct rhash_head *obj)
-{
- void *data;
-
- do {
- rcu_read_lock();
- data = rhashtable_try_insert(ht, key, obj);
- rcu_read_unlock();
- } while (PTR_ERR(data) == -EAGAIN);
-
- return data;
-}
-EXPORT_SYMBOL_GPL(rhashtable_insert_slow);
-
-/**
- * rhashtable_walk_enter - Initialise an iterator
- * @ht: 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.
- */
-void rhashtable_walk_enter(struct rhashtable *ht, struct rhashtable_iter *iter)
-{
- iter->ht = ht;
- iter->p = NULL;
- iter->slot = 0;
- iter->skip = 0;
- iter->end_of_table = 0;
-
- spin_lock(&ht->lock);
- iter->walker.tbl =
- rcu_dereference_protected(ht->tbl, lockdep_is_held(&ht->lock));
- list_add(&iter->walker.list, &iter->walker.tbl->walkers);
- spin_unlock(&ht->lock);
-}
-EXPORT_SYMBOL_GPL(rhashtable_walk_enter);
-
-/**
- * rhashtable_walk_exit - Free an iterator
- * @iter: Hash table Iterator
- *
- * This function frees resources allocated by rhashtable_walk_enter.
- */
-void rhashtable_walk_exit(struct rhashtable_iter *iter)
-{
- spin_lock(&iter->ht->lock);
- if (iter->walker.tbl)
- list_del(&iter->walker.list);
- spin_unlock(&iter->ht->lock);
-}
-EXPORT_SYMBOL_GPL(rhashtable_walk_exit);
-
-/**
- * rhashtable_walk_start_check - Start a hash table walk
- * @iter: Hash table iterator
- *
- * Start a hash table walk at the current iterator position. Note that we take
- * the RCU lock in all cases including when we return an error. So you must
- * always call rhashtable_walk_stop to clean up.
- *
- * Returns zero if successful.
- *
- * Returns -EAGAIN if resize event occured. Note that the iterator
- * will rewind back to the beginning and you may use it immediately
- * by calling rhashtable_walk_next.
- *
- * rhashtable_walk_start is defined as an inline variant that returns
- * void. This is preferred in cases where the caller would ignore
- * resize events and always continue.
- */
-int rhashtable_walk_start_check(struct rhashtable_iter *iter)
- __acquires(RCU)
-{
- struct rhashtable *ht = iter->ht;
- bool rhlist = ht->rhlist;
-
- rcu_read_lock();
-
- spin_lock(&ht->lock);
- if (iter->walker.tbl)
- list_del(&iter->walker.list);
- spin_unlock(&ht->lock);
-
- if (iter->end_of_table)
- return 0;
- if (!iter->walker.tbl) {
- iter->walker.tbl = rht_dereference_rcu(ht->tbl, ht);
- iter->slot = 0;
- iter->skip = 0;
- return -EAGAIN;
- }
-
- if (iter->p && !rhlist) {
- /*
- * We need to validate that 'p' is still in the table, and
- * if so, update 'skip'
- */
- struct rhash_head *p;
- int skip = 0;
- rht_for_each_rcu(p, iter->walker.tbl, iter->slot) {
- skip++;
- if (p == iter->p) {
- iter->skip = skip;
- goto found;
- }
- }
- iter->p = NULL;
- } else if (iter->p && rhlist) {
- /* Need to validate that 'list' is still in the table, and
- * if so, update 'skip' and 'p'.
- */
- struct rhash_head *p;
- struct rhlist_head *list;
- int skip = 0;
- rht_for_each_rcu(p, iter->walker.tbl, iter->slot) {
- for (list = container_of(p, struct rhlist_head, rhead);
- list;
- list = rcu_dereference(list->next)) {
- skip++;
- if (list == iter->list) {
- iter->p = p;
- iter->skip = skip;
- goto found;
- }
- }
- }
- iter->p = NULL;
- }
-found:
- return 0;
-}
-EXPORT_SYMBOL_GPL(rhashtable_walk_start_check);
-
-/**
- * __rhashtable_walk_find_next - Find the next element in a table (or the first
- * one in case of a new walk).
- *
- * @iter: Hash table iterator
- *
- * Returns the found object or NULL when the end of the table is reached.
- *
- * Returns -EAGAIN if resize event occurred.
- */
-static void *__rhashtable_walk_find_next(struct rhashtable_iter *iter)
-{
- struct bucket_table *tbl = iter->walker.tbl;
- struct rhlist_head *list = iter->list;
- struct rhashtable *ht = iter->ht;
- struct rhash_head *p = iter->p;
- bool rhlist = ht->rhlist;
-
- if (!tbl)
- return NULL;
-
- for (; iter->slot < tbl->size; iter->slot++) {
- int skip = iter->skip;
-
- rht_for_each_rcu(p, tbl, iter->slot) {
- if (rhlist) {
- list = container_of(p, struct rhlist_head,
- rhead);
- do {
- if (!skip)
- goto next;
- skip--;
- list = rcu_dereference(list->next);
- } while (list);
-
- continue;
- }
- if (!skip)
- break;
- skip--;
- }
-
-next:
- if (!rht_is_a_nulls(p)) {
- iter->skip++;
- iter->p = p;
- iter->list = list;
- return rht_obj(ht, rhlist ? &list->rhead : p);
- }
-
- iter->skip = 0;
- }
-
- iter->p = NULL;
-
- /* Ensure we see any new tables. */
- smp_rmb();
-
- iter->walker.tbl = rht_dereference_rcu(tbl->future_tbl, ht);
- if (iter->walker.tbl) {
- iter->slot = 0;
- iter->skip = 0;
- return ERR_PTR(-EAGAIN);
- } else {
- iter->end_of_table = true;
- }
-
- return NULL;
-}
-
-/**
- * rhashtable_walk_next - Return the next object and advance the iterator
- * @iter: Hash table iterator
- *
- * Note that you must call rhashtable_walk_stop when you are finished
- * with the walk.
- *
- * Returns the next object or NULL when the end of the table is reached.
- *
- * Returns -EAGAIN if resize event occurred. Note that the iterator
- * will rewind back to the beginning and you may continue to use it.
- */
-void *rhashtable_walk_next(struct rhashtable_iter *iter)
-{
- struct rhlist_head *list = iter->list;
- struct rhashtable *ht = iter->ht;
- struct rhash_head *p = iter->p;
- bool rhlist = ht->rhlist;
-
- if (p) {
- if (!rhlist || !(list = rcu_dereference(list->next))) {
- p = rcu_dereference(p->next);
- list = container_of(p, struct rhlist_head, rhead);
- }
- if (!rht_is_a_nulls(p)) {
- iter->skip++;
- iter->p = p;
- iter->list = list;
- return rht_obj(ht, rhlist ? &list->rhead : p);
- }
-
- /* At the end of this slot, switch to next one and then find
- * next entry from that point.
- */
- iter->skip = 0;
- iter->slot++;
- }
-
- return __rhashtable_walk_find_next(iter);
-}
-EXPORT_SYMBOL_GPL(rhashtable_walk_next);
-
-/**
- * rhashtable_walk_peek - Return the next object but don't advance the iterator
- * @iter: Hash table iterator
- *
- * Returns the next object or NULL when the end of the table is reached.
- *
- * Returns -EAGAIN if resize event occurred. Note that the iterator
- * will rewind back to the beginning and you may continue to use it.
- */
-void *rhashtable_walk_peek(struct rhashtable_iter *iter)
-{
- struct rhlist_head *list = iter->list;
- struct rhashtable *ht = iter->ht;
- struct rhash_head *p = iter->p;
-
- if (p)
- return rht_obj(ht, ht->rhlist ? &list->rhead : p);
-
- /* No object found in current iter, find next one in the table. */
-
- if (iter->skip) {
- /* A nonzero skip value points to the next entry in the table
- * beyond that last one that was found. Decrement skip so
- * we find the current value. __rhashtable_walk_find_next
- * will restore the original value of skip assuming that
- * the table hasn't changed.
- */
- iter->skip--;
- }
-
- return __rhashtable_walk_find_next(iter);
-}
-EXPORT_SYMBOL_GPL(rhashtable_walk_peek);
-
-/**
- * rhashtable_walk_stop - Finish a hash table walk
- * @iter: Hash table iterator
- *
- * Finish a hash table walk. Does not reset the iterator to the start of the
- * hash table.
- */
-void rhashtable_walk_stop(struct rhashtable_iter *iter)
- __releases(RCU)
-{
- struct rhashtable *ht;
- struct bucket_table *tbl = iter->walker.tbl;
-
- if (!tbl)
- goto out;
-
- ht = iter->ht;
-
- spin_lock(&ht->lock);
- if (rcu_head_after_call_rcu(&tbl->rcu, bucket_table_free_rcu))
- /* This bucket table is being freed, don't re-link it. */
- iter->walker.tbl = NULL;
- else
- list_add(&iter->walker.list, &tbl->walkers);
- spin_unlock(&ht->lock);
-
-out:
- rcu_read_unlock();
-}
-EXPORT_SYMBOL_GPL(rhashtable_walk_stop);
-
-static size_t rounded_hashtable_size(const struct rhashtable_params *params)
-{
- size_t retsize;
-
- if (params->nelem_hint)
- retsize = max(roundup_pow_of_two(params->nelem_hint * 4 / 3),
- (unsigned long)params->min_size);
- else
- retsize = max(HASH_DEFAULT_SIZE,
- (unsigned long)params->min_size);
-
- return retsize;
-}
-
-static u32 rhashtable_jhash2(const void *key, u32 length, u32 seed)
-{
- return jhash2(key, length, seed);
-}
-
-/**
- * rhashtable_init - initialize a new hash table
- * @ht: hash table to be initialized
- * @params: configuration parameters
- *
- * Initializes a new hash table based on the provided configuration
- * parameters. A table can be configured either with a variable or
- * fixed length key:
- *
- * Configuration Example 1: Fixed length keys
- * struct test_obj {
- * int key;
- * void * my_member;
- * struct rhash_head node;
- * };
- *
- * struct rhashtable_params params = {
- * .head_offset = offsetof(struct test_obj, node),
- * .key_offset = offsetof(struct test_obj, key),
- * .key_len = sizeof(int),
- * .hashfn = jhash,
- * };
- *
- * Configuration Example 2: Variable length keys
- * struct test_obj {
- * [...]
- * struct rhash_head node;
- * };
- *
- * u32 my_hash_fn(const void *data, u32 len, u32 seed)
- * {
- * struct test_obj *obj = data;
- *
- * return [... hash ...];
- * }
- *
- * struct rhashtable_params params = {
- * .head_offset = offsetof(struct test_obj, node),
- * .hashfn = jhash,
- * .obj_hashfn = my_hash_fn,
- * };
- */
-int rhashtable_init(struct rhashtable *ht,
- const struct rhashtable_params *params)
-{
- struct bucket_table *tbl;
- size_t size;
-
- if ((!params->key_len && !params->obj_hashfn) ||
- (params->obj_hashfn && !params->obj_cmpfn))
- return -EINVAL;
-
- memset(ht, 0, sizeof(*ht));
- mutex_init(&ht->mutex);
- spin_lock_init(&ht->lock);
- memcpy(&ht->p, params, sizeof(*params));
-
- if (params->min_size)
- ht->p.min_size = roundup_pow_of_two(params->min_size);
-
- /* Cap total entries at 2^31 to avoid nelems overflow. */
- ht->max_elems = 1u << 31;
-
- if (params->max_size) {
- ht->p.max_size = rounddown_pow_of_two(params->max_size);
- if (ht->p.max_size < ht->max_elems / 2)
- ht->max_elems = ht->p.max_size * 2;
- }
-
- ht->p.min_size = max_t(u16, ht->p.min_size, HASH_MIN_SIZE);
-
- size = rounded_hashtable_size(&ht->p);
-
- ht->key_len = ht->p.key_len;
- if (!params->hashfn) {
- ht->p.hashfn = jhash;
-
- if (!(ht->key_len & (sizeof(u32) - 1))) {
- ht->key_len /= sizeof(u32);
- ht->p.hashfn = rhashtable_jhash2;
- }
- }
-
- /*
- * This is api initialization and thus we need to guarantee the
- * initial rhashtable allocation. Upon failure, retry with the
- * smallest possible size with __GFP_NOFAIL semantics.
- */
- tbl = bucket_table_alloc(ht, size, GFP_KERNEL);
- if (unlikely(tbl == NULL)) {
- size = max_t(u16, ht->p.min_size, HASH_MIN_SIZE);
- tbl = bucket_table_alloc(ht, size, GFP_KERNEL | __GFP_NOFAIL);
- }
-
- atomic_set(&ht->nelems, 0);
-
- RCU_INIT_POINTER(ht->tbl, tbl);
-
- INIT_WORK(&ht->run_work, rht_deferred_worker);
-
- return 0;
-}
-EXPORT_SYMBOL_GPL(rhashtable_init);
-
-/**
- * rhltable_init - initialize a new hash list table
- * @hlt: hash list table to be initialized
- * @params: configuration parameters
- *
- * Initializes a new hash list table.
- *
- * See documentation for rhashtable_init.
- */
-int rhltable_init(struct rhltable *hlt, const struct rhashtable_params *params)
-{
- int err;
-
- err = rhashtable_init(&hlt->ht, params);
- hlt->ht.rhlist = true;
- return err;
-}
-EXPORT_SYMBOL_GPL(rhltable_init);
-
-static void rhashtable_free_one(struct rhashtable *ht, struct rhash_head *obj,
- void (*free_fn)(void *ptr, void *arg),
- void *arg)
-{
- struct rhlist_head *list;
-
- if (!ht->rhlist) {
- free_fn(rht_obj(ht, obj), arg);
- return;
- }
-
- list = container_of(obj, struct rhlist_head, rhead);
- do {
- obj = &list->rhead;
- list = rht_dereference(list->next, ht);
- free_fn(rht_obj(ht, obj), arg);
- } while (list);
-}
-
-/**
- * rhashtable_free_and_destroy - free elements and destroy hash table
- * @ht: the hash table to destroy
- * @free_fn: callback to release resources of element
- * @arg: pointer passed to free_fn
- *
- * Stops an eventual async resize. If defined, invokes free_fn for each
- * element to releasal resources. Please note that RCU protected
- * readers may still be accessing the elements. Releasing of resources
- * must occur in a compatible manner. Then frees the bucket array.
- *
- * This function will eventually sleep to wait for an async resize
- * to complete. The caller is responsible that no further write operations
- * occurs in parallel.
- */
-void rhashtable_free_and_destroy(struct rhashtable *ht,
- void (*free_fn)(void *ptr, void *arg),
- void *arg)
-{
- struct bucket_table *tbl, *next_tbl;
- unsigned int i;
-
- cancel_work_sync(&ht->run_work);
-
- mutex_lock(&ht->mutex);
- tbl = rht_dereference(ht->tbl, ht);
-restart:
- if (free_fn) {
- for (i = 0; i < tbl->size; i++) {
- struct rhash_head *pos, *next;
-
- cond_resched();
- for (pos = rht_ptr_exclusive(rht_bucket(tbl, i)),
- next = !rht_is_a_nulls(pos) ?
- rht_dereference(pos->next, ht) : NULL;
- !rht_is_a_nulls(pos);
- pos = next,
- next = !rht_is_a_nulls(pos) ?
- rht_dereference(pos->next, ht) : NULL)
- rhashtable_free_one(ht, pos, free_fn, arg);
- }
- }
-
- next_tbl = rht_dereference(tbl->future_tbl, ht);
- bucket_table_free(tbl);
- if (next_tbl) {
- tbl = next_tbl;
- goto restart;
- }
- mutex_unlock(&ht->mutex);
-}
-EXPORT_SYMBOL_GPL(rhashtable_free_and_destroy);
-
-void rhashtable_destroy(struct rhashtable *ht)
-{
- return rhashtable_free_and_destroy(ht, NULL, NULL);
-}
-EXPORT_SYMBOL_GPL(rhashtable_destroy);
-
-struct rhash_lock_head __rcu **__rht_bucket_nested(
- const struct bucket_table *tbl, unsigned int hash)
-{
- const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *));
- unsigned int index = hash & ((1 << tbl->nest) - 1);
- unsigned int size = tbl->size >> tbl->nest;
- unsigned int subhash = hash;
- union nested_table *ntbl;
-
- ntbl = nested_table_top(tbl);
- ntbl = rht_dereference_bucket_rcu(ntbl[index].table, tbl, hash);
- subhash >>= tbl->nest;
-
- while (ntbl && size > (1 << shift)) {
- index = subhash & ((1 << shift) - 1);
- ntbl = rht_dereference_bucket_rcu(ntbl[index].table,
- tbl, hash);
- size >>= shift;
- subhash >>= shift;
- }
-
- if (!ntbl)
- return NULL;
-
- return &ntbl[subhash].bucket;
-
-}
-EXPORT_SYMBOL_GPL(__rht_bucket_nested);
-
-struct rhash_lock_head __rcu **rht_bucket_nested(
- const struct bucket_table *tbl, unsigned int hash)
-{
- static struct rhash_lock_head __rcu *rhnull;
-
- if (!rhnull)
- INIT_RHT_NULLS_HEAD(rhnull);
- return __rht_bucket_nested(tbl, hash) ?: &rhnull;
-}
-EXPORT_SYMBOL_GPL(rht_bucket_nested);
-
-struct rhash_lock_head __rcu **rht_bucket_nested_insert(
- struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash)
-{
- const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *));
- unsigned int index = hash & ((1 << tbl->nest) - 1);
- unsigned int size = tbl->size >> tbl->nest;
- union nested_table *ntbl;
-
- ntbl = nested_table_top(tbl);
- hash >>= tbl->nest;
- ntbl = nested_table_alloc(ht, &ntbl[index].table,
- size <= (1 << shift));
-
- while (ntbl && size > (1 << shift)) {
- index = hash & ((1 << shift) - 1);
- size >>= shift;
- hash >>= shift;
- ntbl = nested_table_alloc(ht, &ntbl[index].table,
- size <= (1 << shift));
- }
-
- if (!ntbl)
- return NULL;
-
- return &ntbl[hash].bucket;
-
-}
-EXPORT_SYMBOL_GPL(rht_bucket_nested_insert);
projects / bcachefs-tools-debian / blobdiff