Merge branch 'rhashtable-next'
Thomas Graf says:
====================
rhashtable updates on top of Herbert's work
Patch 1 is a bugfix for an RCU splash I encountered while testing.
Patch 2 & 3 are pure cleanups. Patch 4 disables automatic shrinking
by default as discussed in previous thread. Patch 5 removes some
rhashtable internal knowledge from nft_hash and fixes another RCU
splash.
I've pushed various rhashtable tests (Netlink, nft) together with a
Makefile to a git tree [0] for easier stress testing.
[0] https://github.com/tgraf/rhashtable
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index d7be9cb..99f2e49 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -2,7 +2,7 @@
* Resizable, Scalable, Concurrent Hash Table
*
* Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
- * Copyright (c) 2014 Thomas Graf <tgraf@suug.ch>
+ * Copyright (c) 2014-2015 Thomas Graf <tgraf@suug.ch>
* Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net>
*
* Code partially derived from nft_hash
@@ -104,6 +104,7 @@
* @min_size: Minimum size while shrinking
* @nulls_base: Base value to generate nulls marker
* @insecure_elasticity: Set to true to disable chain length checks
+ * @automatic_shrinking: Enable automatic shrinking of tables
* @locks_mul: Number of bucket locks to allocate per cpu (default: 128)
* @hashfn: Hash function (default: jhash2 if !(key_len % 4), or jhash)
* @obj_hashfn: Function to hash object
@@ -118,6 +119,7 @@
unsigned int min_size;
u32 nulls_base;
bool insecure_elasticity;
+ bool automatic_shrinking;
size_t locks_mul;
rht_hashfn_t hashfn;
rht_obj_hashfn_t obj_hashfn;
@@ -134,12 +136,10 @@
* @run_work: Deferred worker to expand/shrink asynchronously
* @mutex: Mutex to protect current/future table swapping
* @lock: Spin lock to protect walker list
- * @being_destroyed: True if table is set up for destruction
*/
struct rhashtable {
struct bucket_table __rcu *tbl;
atomic_t nelems;
- bool being_destroyed;
unsigned int key_len;
unsigned int elasticity;
struct rhashtable_params p;
@@ -208,13 +208,13 @@
struct rhashtable *ht, const struct bucket_table *tbl,
const void *key, const struct rhashtable_params params)
{
- unsigned hash;
+ unsigned int hash;
/* params must be equal to ht->p if it isn't constant. */
if (!__builtin_constant_p(params.key_len))
hash = ht->p.hashfn(key, ht->key_len, tbl->hash_rnd);
else if (params.key_len) {
- unsigned key_len = params.key_len;
+ unsigned int key_len = params.key_len;
if (params.hashfn)
hash = params.hashfn(key, key_len, tbl->hash_rnd);
@@ -224,7 +224,7 @@
hash = jhash2(key, key_len / sizeof(u32),
tbl->hash_rnd);
} else {
- unsigned key_len = ht->p.key_len;
+ unsigned int key_len = ht->p.key_len;
if (params.hashfn)
hash = params.hashfn(key, key_len, tbl->hash_rnd);
@@ -332,6 +332,9 @@
void *rhashtable_walk_next(struct rhashtable_iter *iter);
void rhashtable_walk_stop(struct rhashtable_iter *iter) __releases(RCU);
+void rhashtable_free_and_destroy(struct rhashtable *ht,
+ void (*free_fn)(void *ptr, void *arg),
+ void *arg);
void rhashtable_destroy(struct rhashtable *ht);
#define rht_dereference(p, ht) \
@@ -512,7 +515,7 @@
};
const struct bucket_table *tbl;
struct rhash_head *he;
- unsigned hash;
+ unsigned int hash;
rcu_read_lock();
@@ -539,6 +542,7 @@
return NULL;
}
+/* Internal function, please use rhashtable_insert_fast() instead */
static inline int __rhashtable_insert_fast(
struct rhashtable *ht, const void *key, struct rhash_head *obj,
const struct rhashtable_params params)
@@ -550,8 +554,8 @@
struct bucket_table *tbl, *new_tbl;
struct rhash_head *head;
spinlock_t *lock;
- unsigned elasticity;
- unsigned hash;
+ unsigned int elasticity;
+ unsigned int hash;
int err;
restart:
@@ -585,8 +589,8 @@
if (unlikely(rht_grow_above_100(ht, tbl))) {
slow_path:
spin_unlock_bh(lock);
- rcu_read_unlock();
err = rhashtable_insert_rehash(ht);
+ rcu_read_unlock();
if (err)
return err;
@@ -711,6 +715,7 @@
return __rhashtable_insert_fast(ht, key, obj, params);
}
+/* Internal function, please use rhashtable_remove_fast() instead */
static inline int __rhashtable_remove_fast(
struct rhashtable *ht, struct bucket_table *tbl,
struct rhash_head *obj, const struct rhashtable_params params)
@@ -718,7 +723,7 @@
struct rhash_head __rcu **pprev;
struct rhash_head *he;
spinlock_t * lock;
- unsigned hash;
+ unsigned int hash;
int err = -ENOENT;
hash = rht_head_hashfn(ht, tbl, obj, params);
@@ -782,7 +787,8 @@
goto out;
atomic_dec(&ht->nelems);
- if (rht_shrink_below_30(ht, tbl))
+ if (unlikely(ht->p.automatic_shrinking &&
+ rht_shrink_below_30(ht, tbl)))
schedule_work(&ht->run_work);
out:
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 8514f7c..4b7b7e6 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -153,7 +153,7 @@
return new_tbl;
}
-static int rhashtable_rehash_one(struct rhashtable *ht, unsigned old_hash)
+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,
@@ -162,7 +162,7 @@
int err = -ENOENT;
struct rhash_head *head, *next, *entry;
spinlock_t *new_bucket_lock;
- unsigned new_hash;
+ unsigned int new_hash;
rht_for_each(entry, old_tbl, old_hash) {
err = 0;
@@ -199,7 +199,8 @@
return err;
}
-static void rhashtable_rehash_chain(struct rhashtable *ht, unsigned old_hash)
+static void 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;
@@ -244,7 +245,7 @@
struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
struct bucket_table *new_tbl;
struct rhashtable_walker *walker;
- unsigned old_hash;
+ unsigned int old_hash;
new_tbl = rht_dereference(old_tbl->future_tbl, ht);
if (!new_tbl)
@@ -324,11 +325,12 @@
static int rhashtable_shrink(struct rhashtable *ht)
{
struct bucket_table *new_tbl, *old_tbl = rht_dereference(ht->tbl, ht);
- unsigned size = roundup_pow_of_two(atomic_read(&ht->nelems) * 3 / 2);
+ unsigned int size;
int err;
ASSERT_RHT_MUTEX(ht);
+ size = roundup_pow_of_two(atomic_read(&ht->nelems) * 3 / 2);
if (size < ht->p.min_size)
size = ht->p.min_size;
@@ -357,20 +359,17 @@
ht = container_of(work, struct rhashtable, run_work);
mutex_lock(&ht->mutex);
- if (ht->being_destroyed)
- goto unlock;
tbl = rht_dereference(ht->tbl, ht);
tbl = rhashtable_last_table(ht, tbl);
if (rht_grow_above_75(ht, tbl))
rhashtable_expand(ht);
- else if (rht_shrink_below_30(ht, tbl))
+ else if (ht->p.automatic_shrinking && rht_shrink_below_30(ht, tbl))
rhashtable_shrink(ht);
err = rhashtable_rehash_table(ht);
-unlock:
mutex_unlock(&ht->mutex);
if (err)
@@ -379,9 +378,9 @@
static bool rhashtable_check_elasticity(struct rhashtable *ht,
struct bucket_table *tbl,
- unsigned hash)
+ unsigned int hash)
{
- unsigned elasticity = ht->elasticity;
+ unsigned int elasticity = ht->elasticity;
struct rhash_head *head;
rht_for_each(head, tbl, hash)
@@ -431,7 +430,7 @@
struct bucket_table *tbl)
{
struct rhash_head *head;
- unsigned hash;
+ unsigned int hash;
int err;
tbl = rhashtable_last_table(ht, tbl);
@@ -781,21 +780,53 @@
EXPORT_SYMBOL_GPL(rhashtable_init);
/**
- * rhashtable_destroy - destroy hash table
+ * 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
*
- * Frees the bucket array. This function is not rcu safe, therefore the caller
- * has to make sure that no resizing may happen by unpublishing the hashtable
- * and waiting for the quiescent cycle before releasing the bucket array.
+ * 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_destroy(struct rhashtable *ht)
+void rhashtable_free_and_destroy(struct rhashtable *ht,
+ void (*free_fn)(void *ptr, void *arg),
+ void *arg)
{
- ht->being_destroyed = true;
+ const struct bucket_table *tbl;
+ unsigned int i;
cancel_work_sync(&ht->run_work);
mutex_lock(&ht->mutex);
- bucket_table_free(rht_dereference(ht->tbl, ht));
+ tbl = rht_dereference(ht->tbl, ht);
+ if (free_fn) {
+ for (i = 0; i < tbl->size; i++) {
+ struct rhash_head *pos, *next;
+
+ for (pos = rht_dereference(tbl->buckets[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)
+ free_fn(rht_obj(ht, pos), arg);
+ }
+ }
+
+ bucket_table_free(tbl);
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);
diff --git a/net/netfilter/nft_hash.c b/net/netfilter/nft_hash.c
index ad39669..f9ce219 100644
--- a/net/netfilter/nft_hash.c
+++ b/net/netfilter/nft_hash.c
@@ -172,6 +172,7 @@
.head_offset = offsetof(struct nft_hash_elem, node),
.key_offset = offsetof(struct nft_hash_elem, key),
.hashfn = jhash,
+ .automatic_shrinking = true,
};
static int nft_hash_init(const struct nft_set *set,
@@ -187,26 +188,15 @@
return rhashtable_init(priv, ¶ms);
}
+static void nft_free_element(void *ptr, void *arg)
+{
+ nft_hash_elem_destroy((const struct nft_set *)arg, ptr);
+}
+
static void nft_hash_destroy(const struct nft_set *set)
{
- struct rhashtable *priv = nft_set_priv(set);
- const struct bucket_table *tbl;
- struct nft_hash_elem *he;
- struct rhash_head *pos, *next;
- unsigned int i;
-
- /* Stop an eventual async resizing */
- priv->being_destroyed = true;
- mutex_lock(&priv->mutex);
-
- tbl = rht_dereference(priv->tbl, priv);
- for (i = 0; i < tbl->size; i++) {
- rht_for_each_entry_safe(he, pos, next, tbl, i, node)
- nft_hash_elem_destroy(set, he);
- }
- mutex_unlock(&priv->mutex);
-
- rhashtable_destroy(priv);
+ rhashtable_free_and_destroy(nft_set_priv(set), nft_free_element,
+ (void *)set);
}
static bool nft_hash_estimate(const struct nft_set_desc *desc, u32 features,
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index e2f7f28..4caa809 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -3142,6 +3142,7 @@
.obj_hashfn = netlink_hash,
.obj_cmpfn = netlink_compare,
.max_size = 65536,
+ .automatic_shrinking = true,
};
static int __init netlink_proto_init(void)
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 0947105..ee90d74 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -2297,6 +2297,7 @@
.key_len = sizeof(u32), /* portid */
.max_size = 1048576,
.min_size = 256,
+ .automatic_shrinking = true,
};
int tipc_sk_rht_init(struct net *net)