net: suppress lockdep-RCU false positive in FIB trie.

Allow fib_find_node() to be called either under rcu_read_lock()
protection or with RTNL held.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 1 deletions

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index af5d89792860..01ef8ba9025c 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -961,7 +961,9 @@ fib_find_node(struct trie *t, u32 key)
         struct node *n;
 
         pos = 0;
-        n = rcu_dereference(t->trie);
+        n = rcu_dereference_check(t->trie,
+                                  rcu_read_lock_held() ||
+                                  lockdep_rtnl_is_held());
 
         while (n != NULL &&  NODE_TYPE(n) == T_TNODE) {
                 tn = (struct tnode *) n;