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| author | Herbert Xu <herbert@gondor.apana.org.au> | 2015-03-24 00:50:21 +1100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-03-23 22:07:51 -0400 |
| commit | 31ccde2dacea8375c3a7d6fffbf0060ee0d40214 (patch) | |
| tree | 82c65efdd9369d9793996e568ada542ab54bc3c7 /lib | |
| parent | de91b25c8011089f5dd99b9d24743db1f550ca4b (diff) | |
| download | linux-31ccde2dacea8375c3a7d6fffbf0060ee0d40214.tar.gz linux-31ccde2dacea8375c3a7d6fffbf0060ee0d40214.tar.bz2 linux-31ccde2dacea8375c3a7d6fffbf0060ee0d40214.zip | |
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')
| -rw-r--r-- | lib/rhashtable.c | 17 |
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; |