v4.19.13 snapshot.
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
new file mode 100644
index 0000000..30526af
--- /dev/null
+++ b/lib/rhashtable.c
@@ -0,0 +1,1237 @@
+/*
+ * 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
+ *
+ * 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.
+ */
+
+#include <linux/atomic.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/log2.h>
+#include <linux/sched.h>
+#include <linux/rculist.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+#include <linux/jhash.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
+#define BUCKET_LOCKS_PER_CPU 32UL
+
+union nested_table {
+ union nested_table __rcu *table;
+ struct rhash_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)
+{
+ spinlock_t *lock = rht_bucket_lock(tbl, hash);
+
+ return (debug_locks) ? lockdep_is_held(lock) : 1;
+}
+EXPORT_SYMBOL_GPL(lockdep_rht_bucket_is_held);
+#else
+#define ASSERT_RHT_MUTEX(HT)
+#endif
+
+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_raw(ntbl->table);
+ 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 = (union nested_table *)rcu_dereference_raw(tbl->buckets[0]);
+
+ for (i = 0; i < len; i++)
+ nested_table_free(ntbl + i, size);
+
+ kfree(ntbl);
+}
+
+static void bucket_table_free(const struct bucket_table *tbl)
+{
+ if (tbl->nest)
+ nested_bucket_table_free(tbl);
+
+ free_bucket_spinlocks(tbl->locks);
+ 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);
+ }
+
+ rcu_assign_pointer(*prev, ntbl);
+
+ return ntbl;
+}
+
+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, max_locks;
+ int i;
+
+ size = sizeof(*tbl) + nbuckets * sizeof(tbl->buckets[0]);
+ tbl = kvzalloc(size, 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;
+
+ max_locks = size >> 1;
+ if (tbl->nest)
+ max_locks = min_t(size_t, max_locks, 1U << tbl->nest);
+
+ if (alloc_bucket_spinlocks(&tbl->locks, &tbl->locks_mask, max_locks,
+ ht->p.locks_mul, gfp) < 0) {
+ bucket_table_free(tbl);
+ return NULL;
+ }
+
+ 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, 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);
+ struct rhash_head __rcu **pprev = rht_bucket_var(old_tbl, old_hash);
+ int err = -EAGAIN;
+ struct rhash_head *head, *next, *entry;
+ spinlock_t *new_bucket_lock;
+ unsigned int new_hash;
+
+ if (new_tbl->nest)
+ goto out;
+
+ err = -ENOENT;
+
+ rht_for_each(entry, 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);
+
+ new_bucket_lock = rht_bucket_lock(new_tbl, new_hash);
+
+ spin_lock_nested(new_bucket_lock, SINGLE_DEPTH_NESTING);
+ head = rht_dereference_bucket(new_tbl->buckets[new_hash],
+ new_tbl, new_hash);
+
+ RCU_INIT_POINTER(entry->next, head);
+
+ rcu_assign_pointer(new_tbl->buckets[new_hash], entry);
+ spin_unlock(new_bucket_lock);
+
+ rcu_assign_pointer(*pprev, 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);
+ spinlock_t *old_bucket_lock;
+ int err;
+
+ old_bucket_lock = rht_bucket_lock(old_tbl, old_hash);
+
+ spin_lock_bh(old_bucket_lock);
+ while (!(err = rhashtable_rehash_one(ht, old_hash)))
+ ;
+
+ if (err == -ENOENT) {
+ old_tbl->rehash++;
+ err = 0;
+ }
+ spin_unlock_bh(old_bucket_lock);
+
+ 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(&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;
+ spin_unlock(&ht->lock);
+
+ /* Wait for readers. All new readers will see the new
+ * table, and thus no references to the old table will
+ * remain.
+ */
+ call_rcu(&old_tbl->rcu, bucket_table_free_rcu);
+
+ 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 = rhashtable_rehash_table(ht);
+
+ 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 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;
+ struct rhash_head *head;
+ int elasticity;
+
+ elasticity = RHT_ELASTICITY;
+ pprev = rht_bucket_var(tbl, hash);
+ rht_for_each_continue(head, *pprev, 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);
+ rcu_assign_pointer(*pprev, 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 bucket_table *tbl,
+ unsigned int hash,
+ struct rhash_head *obj,
+ void *data)
+{
+ struct rhash_head __rcu **pprev;
+ 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);
+
+ pprev = rht_bucket_insert(ht, tbl, hash);
+ if (!pprev)
+ return ERR_PTR(-ENOMEM);
+
+ head = rht_dereference_bucket(*pprev, 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);
+ }
+
+ rcu_assign_pointer(*pprev, 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;
+ unsigned int hash;
+ spinlock_t *lock;
+ void *data;
+
+ tbl = rcu_dereference(ht->tbl);
+
+ /* All insertions must grab the oldest table containing
+ * the hashed bucket that is yet to be rehashed.
+ */
+ for (;;) {
+ hash = rht_head_hashfn(ht, tbl, obj, ht->p);
+ lock = rht_bucket_lock(tbl, hash);
+ spin_lock_bh(lock);
+
+ if (tbl->rehash <= hash)
+ break;
+
+ spin_unlock_bh(lock);
+ tbl = rht_dereference_rcu(tbl->future_tbl, ht);
+ }
+
+ data = rhashtable_lookup_one(ht, tbl, hash, key, obj);
+ new_tbl = rhashtable_insert_one(ht, tbl, hash, obj, data);
+ if (PTR_ERR(new_tbl) != -EEXIST)
+ data = ERR_CAST(new_tbl);
+
+ while (!IS_ERR_OR_NULL(new_tbl)) {
+ tbl = new_tbl;
+ hash = rht_head_hashfn(ht, tbl, obj, ht->p);
+ spin_lock_nested(rht_bucket_lock(tbl, hash),
+ SINGLE_DEPTH_NESTING);
+
+ data = rhashtable_lookup_one(ht, tbl, hash, key, obj);
+ new_tbl = rhashtable_insert_one(ht, tbl, hash, obj, data);
+ if (PTR_ERR(new_tbl) != -EEXIST)
+ data = ERR_CAST(new_tbl);
+
+ spin_unlock(rht_bucket_lock(tbl, hash));
+ }
+
+ spin_unlock_bh(lock);
+
+ 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_init.
+ */
+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 (tbl->rehash < tbl->size)
+ list_add(&iter->walker.list, &tbl->walkers);
+ else
+ iter->walker.tbl = NULL;
+ 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);
+
+ if (params->locks_mul)
+ ht->p.locks_mul = roundup_pow_of_two(params->locks_mul);
+ else
+ ht->p.locks_mul = BUCKET_LOCKS_PER_CPU;
+
+ 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_dereference(*rht_bucket(tbl, i), ht),
+ 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_head __rcu **rht_bucket_nested(const struct bucket_table *tbl,
+ unsigned int hash)
+{
+ const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *));
+ static struct rhash_head __rcu *rhnull =
+ (struct rhash_head __rcu *)NULLS_MARKER(0);
+ unsigned int index = hash & ((1 << tbl->nest) - 1);
+ unsigned int size = tbl->size >> tbl->nest;
+ unsigned int subhash = hash;
+ union nested_table *ntbl;
+
+ ntbl = (union nested_table *)rcu_dereference_raw(tbl->buckets[0]);
+ 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 &rhnull;
+
+ return &ntbl[subhash].bucket;
+
+}
+EXPORT_SYMBOL_GPL(rht_bucket_nested);
+
+struct rhash_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 = (union nested_table *)rcu_dereference_raw(tbl->buckets[0]);
+ 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);