rhashtable: optimize rhashtable_lookup routine

Define an internal compare function and relevant compare argument,
and then make use of rhashtable_lookup_compare() to lookup key in
hash table, reducing duplicated code between rhashtable_lookup()
and rhashtable_lookup_compare().

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Cc: Thomas Graf <tgraf@suug.ch>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index cbad192..f2fdd7a 100644 (file)
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -612,6 +612,19 @@ restart:
 }
 EXPORT_SYMBOL_GPL(rhashtable_remove);
 
+struct rhashtable_compare_arg {
+       struct rhashtable *ht;
+       const void *key;
+};
+
+static bool rhashtable_compare(void *ptr, void *arg)
+{
+       struct rhashtable_compare_arg *x = arg;
+       struct rhashtable *ht = x->ht;
+
+       return !memcmp(ptr + ht->p.key_offset, x->key, ht->p.key_len);
+}
+
 /**
  * rhashtable_lookup - lookup key in hash table
  * @ht:                hash table
@@ -627,32 +640,14 @@ EXPORT_SYMBOL_GPL(rhashtable_remove);
  */
 void *rhashtable_lookup(struct rhashtable *ht, const void *key)
 {
-       const struct bucket_table *tbl, *old_tbl;
-       struct rhash_head *he;
-       u32 hash;
+       struct rhashtable_compare_arg arg = {
+               .ht = ht,
+               .key = key,
+       };
 
        BUG_ON(!ht->p.key_len);
 
-       rcu_read_lock();
-       old_tbl = rht_dereference_rcu(ht->tbl, ht);
-       tbl = rht_dereference_rcu(ht->future_tbl, ht);
-       hash = key_hashfn(ht, key, ht->p.key_len);
-restart:
-       rht_for_each_rcu(he, tbl, rht_bucket_index(tbl, hash)) {
-               if (memcmp(rht_obj(ht, he) + ht->p.key_offset, key,
-                          ht->p.key_len))
-                       continue;
-               rcu_read_unlock();
-               return rht_obj(ht, he);
-       }
-
-       if (unlikely(tbl != old_tbl)) {
-               tbl = old_tbl;
-               goto restart;
-       }
-
-       rcu_read_unlock();
-       return NULL;
+       return rhashtable_lookup_compare(ht, key, &rhashtable_compare, &arg);
 }
 EXPORT_SYMBOL_GPL(rhashtable_lookup);