Bluetooth: Check earlier for L2CAP ERTM frames to drop

Even when the received tx_seq is expected, the frame still needs to be
dropped if the TX window is exceeded or the receiver is in the local
busy state.
Signed-off-by: Mat Martineau <mathewm@codeaurora.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

net/bluetooth/l2cap_core.c

@@ -3522,9 +3522,6 @@ static inline int l2cap_data_channel_iframe(struct l2cap_chan *chan, u16 rx_cont
 	chan->expected_ack_seq = req_seq;
 	l2cap_drop_acked_frames(chan);
 
-	if (tx_seq == chan->expected_tx_seq)
-		goto expected;
-
 	tx_seq_offset = (tx_seq - chan->buffer_seq) % 64;
 	if (tx_seq_offset < 0)
 		tx_seq_offset += 64;
@@ -3538,6 +3535,9 @@ static inline int l2cap_data_channel_iframe(struct l2cap_chan *chan, u16 rx_cont
 	if (test_bit(CONN_LOCAL_BUSY, &chan->conn_state))
 		goto drop;
 
+	if (tx_seq == chan->expected_tx_seq)
+		goto expected;
+
 	if (test_bit(CONN_SREJ_SENT, &chan->conn_state)) {
 		struct srej_list *first;