rhashtable: remove indirection for grow/shrink decision functions

Currently, all real users of rhashtable default their grow and shrink
decision functions to rht_grow_above_75() and rht_shrink_below_30(),
so that there's currently no need to have this explicitly selectable.

It can/should be generic and private inside rhashtable until a real
use case pops up. Since we can make this private, we'll save us this
additional indirection layer and can improve insertion/deletion time
as well.

Reference: http://patchwork.ozlabs.org/patch/443040/
Suggested-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index cb2104be2135d2278f37cc8f87c0f21d08107987..d438eeb08bff407043b32d5f52f58d08fac8838f 100644 (file)
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -79,12 +79,6 @@ struct rhashtable;
  * @locks_mul: Number of bucket locks to allocate per cpu (default: 128)
  * @hashfn: Function to hash key
  * @obj_hashfn: Function to hash object
- * @grow_decision: If defined, may return true if table should expand
- * @shrink_decision: If defined, may return true if table should shrink
- *
- * Note: when implementing the grow and shrink decision function, min/max
- * shift must be enforced, otherwise, resizing watermarks they set may be
- * useless.
  */
 struct rhashtable_params {
        size_t                  nelem_hint;
@@ -98,10 +92,6 @@ struct rhashtable_params {
        size_t                  locks_mul;
        rht_hashfn_t            hashfn;
        rht_obj_hashfn_t        obj_hashfn;
-       bool                    (*grow_decision)(const struct rhashtable *ht,
-                                                size_t new_size);
-       bool                    (*shrink_decision)(const struct rhashtable *ht,
-                                                  size_t new_size);
 };
 
 /**
@@ -193,9 +183,6 @@ int rhashtable_init(struct rhashtable *ht, struct rhashtable_params *params);
 void rhashtable_insert(struct rhashtable *ht, struct rhash_head *node);
 bool rhashtable_remove(struct rhashtable *ht, struct rhash_head *node);
 
-bool rht_grow_above_75(const struct rhashtable *ht, size_t new_size);
-bool rht_shrink_below_30(const struct rhashtable *ht, size_t new_size);
-
 int rhashtable_expand(struct rhashtable *ht);
 int rhashtable_shrink(struct rhashtable *ht);
 

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index bcf119bfdef426bc28d7aa9f15d1336d3973dd05..090641db4c0d25648951a8078ba1945c8ebc1487 100644 (file)
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -247,26 +247,24 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
  * @ht:                hash table
  * @new_size:  new table size
  */
-bool rht_grow_above_75(const struct rhashtable *ht, size_t new_size)
+static bool rht_grow_above_75(const struct rhashtable *ht, size_t new_size)
 {
        /* Expand table when exceeding 75% load */
        return atomic_read(&ht->nelems) > (new_size / 4 * 3) &&
               (!ht->p.max_shift || atomic_read(&ht->shift) < ht->p.max_shift);
 }
-EXPORT_SYMBOL_GPL(rht_grow_above_75);
 
 /**
  * rht_shrink_below_30 - returns true if nelems < 0.3 * table-size
  * @ht:                hash table
  * @new_size:  new table size
  */
-bool rht_shrink_below_30(const struct rhashtable *ht, size_t new_size)
+static bool rht_shrink_below_30(const struct rhashtable *ht, size_t new_size)
 {
        /* Shrink table beneath 30% load */
        return atomic_read(&ht->nelems) < (new_size * 3 / 10) &&
               (atomic_read(&ht->shift) > ht->p.min_shift);
 }
-EXPORT_SYMBOL_GPL(rht_shrink_below_30);
 
 static void lock_buckets(struct bucket_table *new_tbl,
                         struct bucket_table *old_tbl, unsigned int hash)
@@ -528,40 +526,19 @@ static void rht_deferred_worker(struct work_struct *work)
        list_for_each_entry(walker, &ht->walkers, list)
                walker->resize = true;
 
-       if (ht->p.grow_decision && ht->p.grow_decision(ht, tbl->size))
+       if (rht_grow_above_75(ht, tbl->size))
                rhashtable_expand(ht);
-       else if (ht->p.shrink_decision && ht->p.shrink_decision(ht, tbl->size))
+       else if (rht_shrink_below_30(ht, tbl->size))
                rhashtable_shrink(ht);
-
 unlock:
        mutex_unlock(&ht->mutex);
 }
 
-static void rhashtable_probe_expand(struct rhashtable *ht)
-{
-       const struct bucket_table *new_tbl = rht_dereference_rcu(ht->future_tbl, ht);
-       const struct bucket_table *tbl = rht_dereference_rcu(ht->tbl, ht);
-
-       /* Only adjust the table if no resizing is currently in progress. */
-       if (tbl == new_tbl && ht->p.grow_decision &&
-           ht->p.grow_decision(ht, tbl->size))
-               schedule_work(&ht->run_work);
-}
-
-static void rhashtable_probe_shrink(struct rhashtable *ht)
-{
-       const struct bucket_table *new_tbl = rht_dereference_rcu(ht->future_tbl, ht);
-       const struct bucket_table *tbl = rht_dereference_rcu(ht->tbl, ht);
-
-       /* Only adjust the table if no resizing is currently in progress. */
-       if (tbl == new_tbl && ht->p.shrink_decision &&
-           ht->p.shrink_decision(ht, tbl->size))
-               schedule_work(&ht->run_work);
-}
-
 static void __rhashtable_insert(struct rhashtable *ht, struct rhash_head *obj,
-                               struct bucket_table *tbl, u32 hash)
+                               struct bucket_table *tbl,
+                               const struct bucket_table *old_tbl, u32 hash)
 {
+       bool no_resize_running = tbl == old_tbl;
        struct rhash_head *head;
 
        hash = rht_bucket_index(tbl, hash);
@@ -577,8 +554,8 @@ static void __rhashtable_insert(struct rhashtable *ht, struct rhash_head *obj,
        rcu_assign_pointer(tbl->buckets[hash], obj);
 
        atomic_inc(&ht->nelems);
-
-       rhashtable_probe_expand(ht);
+       if (no_resize_running && rht_grow_above_75(ht, tbl->size))
+               schedule_work(&ht->run_work);
 }
 
 /**
@@ -608,7 +585,7 @@ void rhashtable_insert(struct rhashtable *ht, struct rhash_head *obj)
        hash = obj_raw_hashfn(ht, rht_obj(ht, obj));
 
        lock_buckets(tbl, old_tbl, hash);
-       __rhashtable_insert(ht, obj, tbl, hash);
+       __rhashtable_insert(ht, obj, tbl, old_tbl, hash);
        unlock_buckets(tbl, old_tbl, hash);
 
        rcu_read_unlock();
@@ -690,8 +667,11 @@ found:
        unlock_buckets(new_tbl, old_tbl, new_hash);
 
        if (ret) {
+               bool no_resize_running = new_tbl == old_tbl;
+
                atomic_dec(&ht->nelems);
-               rhashtable_probe_shrink(ht);
+               if (no_resize_running && rht_shrink_below_30(ht, new_tbl->size))
+                       schedule_work(&ht->run_work);
        }
 
        rcu_read_unlock();
@@ -861,7 +841,7 @@ bool rhashtable_lookup_compare_insert(struct rhashtable *ht,
                goto exit;
        }
 
-       __rhashtable_insert(ht, obj, new_tbl, new_hash);
+       __rhashtable_insert(ht, obj, new_tbl, old_tbl, new_hash);
 
 exit:
        unlock_buckets(new_tbl, old_tbl, new_hash);
@@ -1123,8 +1103,7 @@ int rhashtable_init(struct rhashtable *ht, struct rhashtable_params *params)
        if (!ht->p.hash_rnd)
                get_random_bytes(&ht->p.hash_rnd, sizeof(ht->p.hash_rnd));
 
-       if (ht->p.grow_decision || ht->p.shrink_decision)
-               INIT_WORK(&ht->run_work, rht_deferred_worker);
+       INIT_WORK(&ht->run_work, rht_deferred_worker);
 
        return 0;
 }
@@ -1142,8 +1121,7 @@ void rhashtable_destroy(struct rhashtable *ht)
 {
        ht->being_destroyed = true;
 
-       if (ht->p.grow_decision || ht->p.shrink_decision)
-               cancel_work_sync(&ht->run_work);
+       cancel_work_sync(&ht->run_work);
 
        mutex_lock(&ht->mutex);
        bucket_table_free(rht_dereference(ht->tbl, ht));

diff --git a/lib/test_rhashtable.c b/lib/test_rhashtable.c
index f9e9d734446ab31eaa6f70249a2f99fad30c1352..67c7593d1dd69c91f646e21e47b589c40c808837 100644 (file)
--- a/lib/test_rhashtable.c
+++ b/lib/test_rhashtable.c
@@ -201,6 +201,7 @@ static int __init test_rht_init(void)
                .key_offset = offsetof(struct test_obj, value),
                .key_len = sizeof(int),
                .hashfn = jhash,
+               .max_shift = 1, /* we expand/shrink manually here */
                .nulls_base = (3U << RHT_BASE_SHIFT),
        };
        int err;

diff --git a/net/netfilter/nft_hash.c b/net/netfilter/nft_hash.c
index 61e6c407476a618df386c2f14839033398aae14b..c82df0a48fcd8a649921b3fcb6b5d1edd39c6295 100644 (file)
--- a/net/netfilter/nft_hash.c
+++ b/net/netfilter/nft_hash.c
@@ -192,8 +192,6 @@ static int nft_hash_init(const struct nft_set *set,
                .key_offset = offsetof(struct nft_hash_elem, key),
                .key_len = set->klen,
                .hashfn = jhash,
-               .grow_decision = rht_grow_above_75,
-               .shrink_decision = rht_shrink_below_30,
        };
 
        return rhashtable_init(priv, &params);

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 2702673f0f237d7fa43e4649ccc0672f67c895bc..05919bf3f670ed1267e01f14c1de61e78e4d80c4 100644 (file)
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -3126,8 +3126,6 @@ static int __init netlink_proto_init(void)
                .key_len = sizeof(u32), /* portid */
                .hashfn = jhash,
                .max_shift = 16, /* 64K */
-               .grow_decision = rht_grow_above_75,
-               .shrink_decision = rht_shrink_below_30,
        };
 
        if (err != 0)

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index f73e975af80b622c48d5ba92ec1e9504af4755e2..b4d4467d0bb051b09243c62aae2b3b2dca6d90a6 100644 (file)
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -2364,8 +2364,6 @@ int tipc_sk_rht_init(struct net *net)
                .hashfn = jhash,
                .max_shift = 20, /* 1M */
                .min_shift = 8,  /* 256 */
-               .grow_decision = rht_grow_above_75,
-               .shrink_decision = rht_shrink_below_30,
        };
 
        return rhashtable_init(&tn->sk_rht, &rht_params);