1 files changed, 25 insertions, 4 deletions

diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index 31f106e61ca2..b0efb7202957 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -285,6 +285,12 @@ static int l2cap_sock_listen(struct socket *sock, int backlog)
 	sk->sk_max_ack_backlog = backlog;
 	sk->sk_ack_backlog = 0;
 
+	/* Listening channels need to use nested locking in order not to
+	 * cause lockdep warnings when the created child channels end up
+	 * being locked in the same thread as the parent channel.
+	 */
+	atomic_set(&chan->nesting, L2CAP_NESTING_PARENT);
+
 	chan->state = BT_LISTEN;
 	sk->sk_state = BT_LISTEN;
 
@@ -301,7 +307,7 @@ static int l2cap_sock_accept(struct socket *sock, struct socket *newsock,
 	long timeo;
 	int err = 0;
 
-	lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
+	lock_sock_nested(sk, L2CAP_NESTING_PARENT);
 
 	timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
 
@@ -333,7 +339,7 @@ static int l2cap_sock_accept(struct socket *sock, struct socket *newsock,
 
 		release_sock(sk);
 		timeo = schedule_timeout(timeo);
-		lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
+		lock_sock_nested(sk, L2CAP_NESTING_PARENT);
 	}
 	__set_current_state(TASK_RUNNING);
 	remove_wait_queue(sk_sleep(sk), &wait);
@@ -1096,6 +1102,8 @@ static int l2cap_sock_shutdown(struct socket *sock, int how)
 	chan = l2cap_pi(sk)->chan;
 	conn = chan->conn;
 
+	BT_DBG("chan %p state %s", chan, state_to_string(chan->state));
+
 	if (conn)
 		mutex_lock(&conn->chan_lock);
 
@@ -1153,12 +1161,16 @@ static void l2cap_sock_cleanup_listen(struct sock *parent)
 {
 	struct sock *sk;
 
-	BT_DBG("parent %p", parent);
+	BT_DBG("parent %p state %s", parent,
+	       state_to_string(parent->sk_state));
 
 	/* Close not yet accepted channels */
 	while ((sk = bt_accept_dequeue(parent, NULL))) {
 		struct l2cap_chan *chan = l2cap_pi(sk)->chan;
 
+		BT_DBG("child chan %p state %s", chan,
+		       state_to_string(chan->state));
+
 		l2cap_chan_lock(chan);
 		__clear_chan_timer(chan);
 		l2cap_chan_close(chan, ECONNRESET);
@@ -1246,7 +1258,16 @@ static void l2cap_sock_teardown_cb(struct l2cap_chan *chan, int err)
 	struct sock *sk = chan->data;
 	struct sock *parent;
 
-	lock_sock(sk);
+	BT_DBG("chan %p state %s", chan, state_to_string(chan->state));
+
+	/* This callback can be called both for server (BT_LISTEN)
+	 * sockets as well as "normal" ones. To avoid lockdep warnings
+	 * with child socket locking (through l2cap_sock_cleanup_listen)
+	 * we need separation into separate nesting levels. The simplest
+	 * way to accomplish this is to inherit the nesting level used
+	 * for the channel.
+	 */
+	lock_sock_nested(sk, atomic_read(&chan->nesting));
 
 	parent = bt_sk(sk)->parent;