Re: [PATCH v3 03/15] lockdep: Refactor lookup_chain_cache()

@@ -2215,6 +2178,75 @@ cache_hit:
        return 1;
 }

+/*
+ * Look up a dependency chain.
+ */
+static inline struct lock_chain *lookup_chain_cache(u64 chain_key)
+{
+       struct hlist_head *hash_head = chainhashentry(chain_key);
+       struct lock_chain *chain;
+
+       /*
+        * We can walk it lock-free, because entries only get added
+        * to the hash:
+        */
+       hlist_for_each_entry_rcu(chain, hash_head, entry) {
+               if (chain->chain_key == chain_key) {
+                       debug_atomic_inc(chain_lookup_hits);
+                       return chain;
+               }
+       }
+       return NULL;
+}