diff options
| -rw-r--r-- | include/linux/rhashtable.h | 13 | ||||
| -rw-r--r-- | lib/rhashtable.c | 52 |
2 files changed, 16 insertions, 49 deletions
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h index ae9c0f71f311..3864193d5e2e 100644 --- a/include/linux/rhashtable.h +++ b/include/linux/rhashtable.h @@ -63,7 +63,6 @@ struct bucket_table { unsigned int size; unsigned int nest; - unsigned int rehash; u32 hash_rnd; unsigned int locks_mask; spinlock_t *locks; @@ -776,12 +775,6 @@ static inline int rhltable_insert( * @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. * @@ -837,12 +830,6 @@ static inline void *rhashtable_lookup_get_insert_fast( * @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 diff --git a/lib/rhashtable.c b/lib/rhashtable.c index 0a105d4af166..776b3a82d3a1 100644 --- a/lib/rhashtable.c +++ b/lib/rhashtable.c @@ -197,6 +197,7 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht, return NULL; } + rcu_head_init(&tbl->rcu); INIT_LIST_HEAD(&tbl->walkers); tbl->hash_rnd = get_random_u32(); @@ -280,10 +281,9 @@ static int rhashtable_rehash_chain(struct rhashtable *ht, while (!(err = rhashtable_rehash_one(ht, old_hash))) ; - if (err == -ENOENT) { - old_tbl->rehash++; + if (err == -ENOENT) err = 0; - } + spin_unlock_bh(old_bucket_lock); return err; @@ -330,13 +330,16 @@ static int rhashtable_rehash_table(struct rhashtable *ht) 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. + * 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; } @@ -578,46 +581,22 @@ static void *rhashtable_try_insert(struct rhashtable *ht, const void *key, 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); + new_tbl = rcu_dereference(ht->tbl); - while (!IS_ERR_OR_NULL(new_tbl)) { + do { tbl = new_tbl; hash = rht_head_hashfn(ht, tbl, obj, ht->p); - spin_lock_nested(rht_bucket_lock(tbl, hash), - SINGLE_DEPTH_NESTING); + spin_lock_bh(rht_bucket_lock(tbl, hash)); 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); + spin_unlock_bh(rht_bucket_lock(tbl, hash)); + } while (!IS_ERR_OR_NULL(new_tbl)); if (PTR_ERR(data) == -EAGAIN) data = ERR_PTR(rhashtable_insert_rehash(ht, tbl) ?: @@ -939,10 +918,11 @@ void rhashtable_walk_stop(struct rhashtable_iter *iter) ht = iter->ht; spin_lock(&ht->lock); - if (tbl->rehash < tbl->size) - list_add(&iter->walker.list, &tbl->walkers); - else + 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: |