[PATCH 05/19] Bluetooth: Channel move request handling

[Mat Martineau <mathewm@codeaurora.org>]

On receipt of a channel move request, the request must be validated
based on the L2CAP mode, connection state, and controller
capabilities.  ERTM channels must have their state machines cleared
and transmission paused while the channel move takes place.

If the channel is being moved to an AMP controller then
an AMP physical link must be prepared.  Moving the channel back to
BR/EDR proceeds immediately.

Signed-off-by: Mat Martineau <mathewm@codeaurora.org>
---
 net/bluetooth/l2cap_core.c | 98 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 97 insertions(+), 1 deletion(-)

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index a55644f..649c06b 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -995,6 +995,41 @@ void l2cap_send_conn_req(struct l2cap_chan *chan)
 	l2cap_send_cmd(conn, chan->ident, L2CAP_CONN_REQ, sizeof(req), &req);
 }
 
+static void l2cap_move_setup(struct l2cap_chan *chan)
+{
+	struct sk_buff *skb;
+
+	BT_DBG("chan %p", chan);
+
+	if (chan->mode != L2CAP_MODE_ERTM)
+		return;
+
+	__clear_retrans_timer(chan);
+	__clear_monitor_timer(chan);
+	__clear_ack_timer(chan);
+
+	chan->retry_count = 0;
+	skb_queue_walk(&chan->tx_q, skb) {
+		if (bt_cb(skb)->control.retries)
+			bt_cb(skb)->control.retries = 1;
+		else
+			break;
+	}
+
+	chan->expected_tx_seq = chan->buffer_seq;
+
+	clear_bit(CONN_REJ_ACT, &chan->conn_state);
+	clear_bit(CONN_SREJ_ACT, &chan->conn_state);
+	l2cap_seq_list_clear(&chan->retrans_list);
+	l2cap_seq_list_clear(&chan->srej_list);
+	skb_queue_purge(&chan->srej_q);
+
+	chan->tx_state = L2CAP_TX_STATE_XMIT;
+	chan->rx_state = L2CAP_RX_STATE_MOVE;
+
+	set_bit(CONN_REMOTE_BUSY, &chan->conn_state);
+}
+
 static void l2cap_chan_ready(struct l2cap_chan *chan)
 {
 	/* This clears all conf flags, including CONF_NOT_COMPLETE */
@@ -4171,7 +4206,68 @@ static inline int l2cap_move_channel_req(struct l2cap_conn *conn,
 
 	chan = l2cap_get_chan_by_dcid(conn, icid);
 
-	/* Placeholder: Always refuse */
+	if (!chan || chan->scid < L2CAP_CID_DYN_START ||
+	    (chan->mode != L2CAP_MODE_ERTM &&
+	     chan->mode != L2CAP_MODE_STREAMING)) {
+		result = L2CAP_MR_NOT_ALLOWED;
+		goto send_move_response;
+	}
+
+	if (chan->local_amp_id == req->dest_amp_id) {
+		result = L2CAP_MR_SAME_ID;
+		goto send_move_response;
+	}
+
+	if (req->dest_amp_id) {
+		struct hci_dev *hdev;
+		hdev = hci_dev_get(req->dest_amp_id);
+		if (!hdev || hdev->dev_type != HCI_AMP ||
+		    !test_bit(HCI_UP, &hdev->flags)) {
+			if (hdev)
+				hci_dev_put(hdev);
+
+			result = L2CAP_MR_BAD_ID;
+			goto send_move_response;
+		}
+		hci_dev_put(hdev);
+	}
+
+	if (((chan->move_state != L2CAP_MOVE_STABLE &&
+	    chan->move_state != L2CAP_MOVE_WAIT_PREPARE) ||
+	    chan->move_role != L2CAP_MOVE_ROLE_NONE) &&
+	    bacmp(conn->src, conn->dst) > 0) {
+		result = L2CAP_MR_COLLISION;
+		goto send_move_response;
+	}
+
+	if (chan->chan_policy == BT_CHANNEL_POLICY_BREDR_ONLY) {
+		result = L2CAP_MR_NOT_ALLOWED;
+		goto send_move_response;
+	}
+
+	chan->ident = cmd->ident;
+	chan->move_role = L2CAP_MOVE_ROLE_RESPONDER;
+	l2cap_move_setup(chan);
+	chan->move_id = req->dest_amp_id;
+	icid = chan->dcid;
+
+	if (req->dest_amp_id == 0) {
+		/* Moving to BR/EDR */
+		if (test_bit(CONN_LOCAL_BUSY, &chan->conn_state)) {
+			chan->move_state = L2CAP_MOVE_WAIT_LOCAL_BUSY;
+			result = L2CAP_MR_PEND;
+		} else {
+			chan->move_state = L2CAP_MOVE_WAIT_CONFIRM;
+			result = L2CAP_MR_SUCCESS;
+		}
+	} else {
+		chan->move_state = L2CAP_MOVE_WAIT_PREPARE;
+		/* Placeholder - uncomment when amp functions are available */
+		/*amp_accept_physical(chan, req->dest_amp_id);*/
+		result = L2CAP_MR_PEND;
+	}
+
+send_move_response:
 	l2cap_send_move_chan_rsp(conn, cmd->ident, icid, result);
 
 	if (chan)
-- 
1.7.12.3

--
Mat Martineau

Employee of Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation