diff options
| -rw-r--r-- | include/linux/rhashtable.h | 33 | ||||
| -rw-r--r-- | lib/rhashtable.c | 17 |
2 files changed, 43 insertions, 7 deletions
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h index 3851952781d7..bc2488b98321 100644 --- a/include/linux/rhashtable.h +++ b/include/linux/rhashtable.h @@ -19,6 +19,7 @@ #include <linux/compiler.h> #include <linux/errno.h> +#include <linux/jhash.h> #include <linux/list_nulls.h> #include <linux/workqueue.h> #include <linux/mutex.h> @@ -103,7 +104,7 @@ struct rhashtable; * @min_size: Minimum size while shrinking * @nulls_base: Base value to generate nulls marker * @locks_mul: Number of bucket locks to allocate per cpu (default: 128) - * @hashfn: Function to hash key + * @hashfn: Hash function (default: jhash2 if !(key_len % 4), or jhash) * @obj_hashfn: Function to hash object * @obj_cmpfn: Function to compare key with object */ @@ -125,6 +126,7 @@ struct rhashtable_params { * struct rhashtable - Hash table handle * @tbl: Bucket table * @nelems: Number of elements in table + * @key_len: Key length for hashfn * @p: Configuration parameters * @run_work: Deferred worker to expand/shrink asynchronously * @mutex: Mutex to protect current/future table swapping @@ -134,6 +136,7 @@ struct rhashtable { struct bucket_table __rcu *tbl; atomic_t nelems; bool being_destroyed; + unsigned int key_len; struct rhashtable_params p; struct work_struct run_work; struct mutex mutex; @@ -199,13 +202,31 @@ static inline unsigned int rht_key_hashfn( struct rhashtable *ht, const struct bucket_table *tbl, const void *key, const struct rhashtable_params params) { + unsigned hash; + /* params must be equal to ht->p if it isn't constant. */ - unsigned key_len = __builtin_constant_p(params.key_len) ? - (params.key_len ?: ht->p.key_len) : - params.key_len; + if (!__builtin_constant_p(params.key_len)) + hash = ht->p.hashfn(key, ht->key_len, tbl->hash_rnd); + else if (params.key_len) { + unsigned key_len = params.key_len; + + if (params.hashfn) + hash = params.hashfn(key, key_len, tbl->hash_rnd); + else if (key_len & (sizeof(u32) - 1)) + hash = jhash(key, key_len, tbl->hash_rnd); + else + hash = jhash2(key, key_len / sizeof(u32), + tbl->hash_rnd); + } else { + unsigned key_len = ht->p.key_len; + + if (params.hashfn) + hash = params.hashfn(key, key_len, tbl->hash_rnd); + else + hash = jhash(key, key_len, tbl->hash_rnd); + } - return rht_bucket_index(tbl, params.hashfn(key, key_len, - tbl->hash_rnd)); + return rht_bucket_index(tbl, hash); } static inline unsigned int rht_head_hashfn( 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; |