Bluetooth: Make __l2cap_wait_ack more efficient

Use chan->state instead of chan->conn because waiting
for ACK's is only possible in the BT_CONNECTED state.
Also avoids reference to the conn structure so makes
locking easier.

Only call __l2cap_wait_ack() when the needed condition
of chan->unacked_frames > 0 && chan->state == BT_CONNECTED
is true and convert the while loop to a do while loop.

__l2cap_wait_ack() change the function prototype to
pass in the chan variable as chan is already available
in the calling function l2cap_sock_shutdown(). Avoids
locking issues.
Signed-off-by: Dean Jenkins <Dean_Jenkins@mentor.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/l2cap_sock.c

@@ -1054,16 +1054,15 @@ static void l2cap_sock_kill(struct sock *sk)
 	sock_put(sk);
 }
 
-static int __l2cap_wait_ack(struct sock *sk)
+static int __l2cap_wait_ack(struct sock *sk, struct l2cap_chan *chan)
 {
-	struct l2cap_chan *chan = l2cap_pi(sk)->chan;
 	DECLARE_WAITQUEUE(wait, current);
 	int err = 0;
 	int timeo = HZ/5;
 
 	add_wait_queue(sk_sleep(sk), &wait);
 	set_current_state(TASK_INTERRUPTIBLE);
-	while (chan->unacked_frames > 0 && chan->conn) {
+	do {
 		if (!timeo)
 			timeo = HZ/5;
 
@@ -1080,7 +1079,10 @@ static int __l2cap_wait_ack(struct sock *sk)
 		err = sock_error(sk);
 		if (err)
 			break;
-	}
+
+	} while (chan->unacked_frames > 0 &&
+		 chan->state == BT_CONNECTED);
+
 	set_current_state(TASK_RUNNING);
 	remove_wait_queue(sk_sleep(sk), &wait);
 	return err;
@@ -1115,8 +1117,10 @@ static int l2cap_sock_shutdown(struct socket *sock, int how)
 	lock_sock(sk);
 
 	if (!sk->sk_shutdown) {
-		if (chan->mode == L2CAP_MODE_ERTM)
-			err = __l2cap_wait_ack(sk);
+		if (chan->mode == L2CAP_MODE_ERTM &&
+		    chan->unacked_frames > 0 &&
+		    chan->state == BT_CONNECTED)
+			err = __l2cap_wait_ack(sk, chan);
 
 		sk->sk_shutdown = SHUTDOWN_MASK;