rhashtable: Avoid calculating hash again to unlock

Caching the lock pointer avoids having to hash on the object
again to unlock the bucket locks.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 6 deletions

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index eae26a67bd18..09a7ada89ade 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -384,14 +384,16 @@ static bool __rhashtable_insert(struct rhashtable *ht, struct rhash_head *obj,
         struct rhash_head *head;
         bool no_resize_running;
         unsigned hash;
+        spinlock_t *old_lock;
         bool success = true;
 
         rcu_read_lock();
 
         old_tbl = rht_dereference_rcu(ht->tbl, ht);
         hash = head_hashfn(ht, old_tbl, obj);
+        old_lock = bucket_lock(old_tbl, hash);
 
-        spin_lock_bh(bucket_lock(old_tbl, hash));
+        spin_lock_bh(old_lock);
 
         /* Because we have already taken the bucket lock in old_tbl,
          * if we find that future_tbl is not yet visible then that
@@ -428,13 +430,10 @@ static bool __rhashtable_insert(struct rhashtable *ht, struct rhash_head *obj,
                 schedule_work(&ht->run_work);
 
 exit:
-        if (tbl != old_tbl) {
-                hash = head_hashfn(ht, tbl, obj);
+        if (tbl != old_tbl)
                 spin_unlock(bucket_lock(tbl, hash));
-        }
 
-        hash = head_hashfn(ht, old_tbl, obj);
-        spin_unlock_bh(bucket_lock(old_tbl, hash));
+        spin_unlock_bh(old_lock);
 
         rcu_read_unlock();