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>

1 files changed, 18 insertions, 23 deletions

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index cbad192d3b3d..f2fdd7a7cb16 100644
--- 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);