sock: fix lockdep annotation in release_sock

During release_sock we use callbacks to finish the processing
of outstanding skbs on the socket. We actually are still locked,
sk_locked.owned == 1, but we already told lockdep that the mutex
is released. This could lead to false positives in lockdep for
lockdep_sock_is_held (we don't hold the slock spinlock during processing
the outstanding skbs).

I took over this patch from Eric Dumazet and tested it.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 6 insertions, 6 deletions

diff --git a/include/net/sock.h b/include/net/sock.h
index 1decb7a22261..91cee51086dc 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1333,7 +1333,12 @@ static inline void sk_wmem_free_skb(struct sock *sk, struct sk_buff *skb)
 
 static inline void sock_release_ownership(struct sock *sk)
 {
-        sk->sk_lock.owned = 0;
+        if (sk->sk_lock.owned) {
+                sk->sk_lock.owned = 0;
+
+                /* The sk_lock has mutex_unlock() semantics: */
+                mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_);
+        }
 }
 
 /*
diff --git a/net/core/sock.c b/net/core/sock.c
index 2ce76e82857f..152274d188ef 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2483,11 +2483,6 @@ EXPORT_SYMBOL(lock_sock_nested);
 
 void release_sock(struct sock *sk)
 {
-        /*
-         * The sk_lock has mutex_unlock() semantics:
-         */
-        mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_);
-
         spin_lock_bh(&sk->sk_lock.slock);
         if (sk->sk_backlog.tail)
                 __release_sock(sk);