[PATCH RFC 4/6] rhashtable: abstract out function to get hash

[Tom Herbert]

Split out most of rht_key_hashfn which is calculating the hash into
its own function. This way the hash function can be called separately to
get the hash value.

Signed-off-by: Tom Herbert <t...@herbertland.com>
---
 include/linux/rhashtable.h | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index fd82584..e398a62 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -208,34 +208,42 @@ static inline unsigned int rht_bucket_index(const struct 
bucket_table *tbl,
        return (hash >> RHT_HASH_RESERVED_SPACE) & (tbl->size - 1);
 }
 
-static inline unsigned int rht_key_hashfn(
-       struct rhashtable *ht, const struct bucket_table *tbl,
-       const void *key, const struct rhashtable_params params)
+static inline unsigned int rht_key_get_hash(struct rhashtable *ht,
+       const void *key, const struct rhashtable_params params,
+       unsigned int hash_rnd)
 {
        unsigned int hash;
 
        /* params must be equal to ht->p if it isn't constant. */
        if (!__builtin_constant_p(params.key_len))
-               hash = ht->p.hashfn(key, ht->key_len, tbl->hash_rnd);
+               hash = ht->p.hashfn(key, ht->key_len, hash_rnd);
        else if (params.key_len) {
                unsigned int key_len = params.key_len;
 
                if (params.hashfn)
-                       hash = params.hashfn(key, key_len, tbl->hash_rnd);
+                       hash = params.hashfn(key, key_len, hash_rnd);
                else if (key_len & (sizeof(u32) - 1))
-                       hash = jhash(key, key_len, tbl->hash_rnd);
+                       hash = jhash(key, key_len, hash_rnd);
                else
-                       hash = jhash2(key, key_len / sizeof(u32),
-                                     tbl->hash_rnd);
+                       hash = jhash2(key, key_len / sizeof(u32), hash_rnd);
        } else {
                unsigned int key_len = ht->p.key_len;
 
                if (params.hashfn)
-                       hash = params.hashfn(key, key_len, tbl->hash_rnd);
+                       hash = params.hashfn(key, key_len, hash_rnd);
                else
-                       hash = jhash(key, key_len, tbl->hash_rnd);
+                       hash = jhash(key, key_len, hash_rnd);
        }
 
+       return hash;
+}
+
+static inline unsigned int rht_key_hashfn(
+       struct rhashtable *ht, const struct bucket_table *tbl,
+       const void *key, const struct rhashtable_params params)
+{
+       unsigned int hash = rht_key_get_hash(ht, key, params, tbl->hash_rnd);
+
        return rht_bucket_index(tbl, hash);
 }
 
-- 
2.8.0.rc2