Bluetooth: l2cap: Fix lost wakeup waiting for ERTM acks

Fix race condition which can result in missing wakeup during
l2cap socket shutdown.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

net/bluetooth/l2cap_core.c

@@ -1159,9 +1159,8 @@ int __l2cap_wait_ack(struct sock *sk)
 	int timeo = HZ/5;
 
 	add_wait_queue(sk_sleep(sk), &wait);
-	while ((chan->unacked_frames > 0 && chan->conn)) {
 	set_current_state(TASK_INTERRUPTIBLE);
-
+	while (chan->unacked_frames > 0 && chan->conn) {
 		if (!timeo)
 			timeo = HZ/5;
 
@@ -1173,6 +1172,7 @@ int __l2cap_wait_ack(struct sock *sk)
 		release_sock(sk);
 		timeo = schedule_timeout(timeo);
 		lock_sock(sk);
+		set_current_state(TASK_INTERRUPTIBLE);
 
 		err = sock_error(sk);
 		if (err)