netdev - [PATCH net-next] net: use proper lockdep annotation in __sk_dst

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Message-ID: <1488828235.9415.390.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Mon, 06 Mar 2017 11:23:55 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     David Miller <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>
Subject: [PATCH net-next] net: use proper lockdep annotation in
 __sk_dst_set()

From: Eric Dumazet <edumazet@...gle.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 <edumazet@...gle.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);
 }