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/lib/rhashtable.c b/lib/rhashtable.c
index bcf119b..090641d 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -247,26 +247,24 @@
* @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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
{
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));