[PATCH net-next] net: use proper lockdep annotation in __sk_dst_set()

[Eric Dumazet]

From: Eric Dumazet <eduma...@google.com>

__sk_dst_set() must be called while we own the socket.

We can get proper lockdep coverage using lockdep_sock_is_held()
and rcu_dereference_protected()

Signed-off-by: Eric Dumazet <eduma...@google.com>
---
 include/net/sock.h |    7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 
5e5997654db6454f82179cc35c4bc22e89d0c06f..6db7693b9e61854abaa461706f2678c6d429b73f
 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1780,11 +1780,8 @@ __sk_dst_set(struct sock *sk, struct dst_entry *dst)
 
        sk_tx_queue_clear(sk);
        sk->sk_dst_pending_confirm = 0;
-       /*
-        * This can be called while sk is owned by the caller only,
-        * with no state that can be checked in a rcu_dereference_check() cond
-        */
-       old_dst = rcu_dereference_raw(sk->sk_dst_cache);
+       old_dst = rcu_dereference_protected(sk->sk_dst_cache,
+                                           lockdep_sock_is_held(sk));
        rcu_assign_pointer(sk->sk_dst_cache, dst);
        dst_release(old_dst);
 }