[PATCH 4.9 16/28] lib/rhashtable: consider param->min_size when setting initial table size

From: Greg Kroah-Hartman
Date: Mon Jul 23 2018 - 08:32:01 EST


4.9-stable review patch. If anyone has any objections, please let me know.

------------------

From: Davidlohr Bueso <dave@xxxxxxxxxxxx>

[ Upstream commit 107d01f5ba10f4162c38109496607eb197059064 ]

rhashtable_init() currently does not take into account the user-passed
min_size parameter unless param->nelem_hint is set as well. As such,
the default size (number of buckets) will always be HASH_DEFAULT_SIZE
even if the smallest allowed size is larger than that. Remediate this
by unconditionally calling into rounded_hashtable_size() and handling
things accordingly.

Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
Acked-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
lib/rhashtable.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)

--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -783,8 +783,16 @@ EXPORT_SYMBOL_GPL(rhashtable_walk_stop);

static size_t rounded_hashtable_size(const struct rhashtable_params *params)
{
- return max(roundup_pow_of_two(params->nelem_hint * 4 / 3),
- (unsigned long)params->min_size);
+ 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)
@@ -841,8 +849,6 @@ int rhashtable_init(struct rhashtable *h
struct bucket_table *tbl;
size_t size;

- size = HASH_DEFAULT_SIZE;
-
if ((!params->key_len && !params->obj_hashfn) ||
(params->obj_hashfn && !params->obj_cmpfn))
return -EINVAL;
@@ -869,8 +875,7 @@ int rhashtable_init(struct rhashtable *h

ht->p.min_size = max(ht->p.min_size, HASH_MIN_SIZE);

- if (params->nelem_hint)
- size = rounded_hashtable_size(&ht->p);
+ size = rounded_hashtable_size(&ht->p);

/* The maximum (not average) chain length grows with the
* size of the hash table, at a rate of (log N)/(log log N).