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authorHerbert Xu <herbert@gondor.apana.org.au>2015-03-24 00:50:21 +1100
committerDavid S. Miller <davem@davemloft.net>2015-03-23 22:07:51 -0400
commit31ccde2dacea8375c3a7d6fffbf0060ee0d40214 (patch)
tree82c65efdd9369d9793996e568ada542ab54bc3c7 /lib/rhashtable.c
parentde91b25c8011089f5dd99b9d24743db1f550ca4b (diff)
downloadlinux-31ccde2dacea8375c3a7d6fffbf0060ee0d40214.tar.gz
linux-31ccde2dacea8375c3a7d6fffbf0060ee0d40214.tar.xz
rhashtable: Allow hashfn to be unset
Since every current rhashtable user uses jhash as their hash function, the fact that jhash is an inline function causes each user to generate a copy of its code. This function provides a solution to this problem by allowing hashfn to be unset. In which case rhashtable will automatically set it to jhash. Furthermore, if the key length is a multiple of 4, we will switch over to jhash2. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'lib/rhashtable.c')
-rw-r--r--lib/rhashtable.c17
1 files changed, 16 insertions, 1 deletions
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 618a3f00d712..798f01d64ab0 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -532,6 +532,11 @@ static size_t rounded_hashtable_size(const struct rhashtable_params *params)
(unsigned long)params->min_size);
}
+static u32 rhashtable_jhash2(const void *key, u32 length, u32 seed)
+{
+ return jhash2(key, length, seed);
+}
+
/**
* rhashtable_init - initialize a new hash table
* @ht: hash table to be initialized
@@ -583,7 +588,7 @@ int rhashtable_init(struct rhashtable *ht,
size = HASH_DEFAULT_SIZE;
- if ((!(params->key_len && params->hashfn) && !params->obj_hashfn) ||
+ if ((!params->key_len && !params->obj_hashfn) ||
(params->obj_hashfn && !params->obj_cmpfn))
return -EINVAL;
@@ -610,6 +615,16 @@ int rhashtable_init(struct rhashtable *ht,
else
ht->p.locks_mul = BUCKET_LOCKS_PER_CPU;
+ ht->key_len = ht->p.key_len;
+ if (!params->hashfn) {
+ ht->p.hashfn = jhash;
+
+ if (!(ht->key_len & (sizeof(u32) - 1))) {
+ ht->key_len /= sizeof(u32);
+ ht->p.hashfn = rhashtable_jhash2;
+ }
+ }
+
tbl = bucket_table_alloc(ht, size);
if (tbl == NULL)
return -ENOMEM;