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Commit 30afb5b2 authored by Gustavo Padovan's avatar Gustavo Padovan Committed by Marcel Holtmann
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Bluetooth: Initial support for retransmission of packets with REJ frames 



When receiving an I-frame with unexpected txSeq, receiver side start the
recovery procedure by sending a REJ S-frame to the transmitter side. So
the transmitter can re-send the lost I-frame.

This patch just adds a basic support for retransmission, it doesn't
mean that ERTM now has full support for packet retransmission.

Signed-off-by: default avatarGustavo F. Padovan <gustavo@las.ic.unicamp.br>
Signed-off-by: default avatarMarcel Holtmann <marcel@holtmann.org>
parent c74e560c

include/net/bluetooth/l2cap.h

+1 −0
Original line number Diff line number Diff line
@@ -351,6 +351,7 @@ struct l2cap_pinfo { 
#define L2CAP_CONF_MAX_CONF_RSP 2



#define L2CAP_CONN_SAR_SDU         0x01

#define L2CAP_CONN_UNDER_REJ       0x02



static inline int l2cap_tx_window_full(struct sock *sk)

{

net/bluetooth/l2cap.c

+43 −14
Original line number Diff line number Diff line
@@ -2951,8 +2951,9 @@ static inline int l2cap_data_channel_iframe(struct sock *sk, u16 rx_control, str 


	BT_DBG("sk %p rx_control 0x%4.4x len %d", sk, rx_control, skb->len);



	if (tx_seq != pi->expected_tx_seq)

		return -EINVAL;

	if (tx_seq == pi->expected_tx_seq) {

		if (pi->conn_state & L2CAP_CONN_UNDER_REJ)

			pi->conn_state &= ~L2CAP_CONN_UNDER_REJ;



		err = l2cap_sar_reassembly_sdu(sk, skb, rx_control);

		if (err < 0)
@@ -2961,12 +2962,25 @@ static inline int l2cap_data_channel_iframe(struct sock *sk, u16 rx_control, str 
		pi->expected_tx_seq = (pi->expected_tx_seq + 1) % 64;

		pi->num_to_ack = (pi->num_to_ack + 1) % L2CAP_DEFAULT_NUM_TO_ACK;

		if (pi->num_to_ack == L2CAP_DEFAULT_NUM_TO_ACK - 1) {

		tx_control |= L2CAP_CTRL_FRAME_TYPE;

			tx_control |= L2CAP_SUPER_RCV_READY;

			tx_control |= pi->expected_tx_seq << L2CAP_CTRL_REQSEQ_SHIFT;

		err = l2cap_send_sframe(pi, tx_control);

			goto send;

		}

	return err;

	} else {

		/* Unexpected txSeq. Send a REJ S-frame */

		kfree_skb(skb);

		if (!(pi->conn_state & L2CAP_CONN_UNDER_REJ)) {

			tx_control |= L2CAP_SUPER_REJECT;

			tx_control |= pi->expected_tx_seq << L2CAP_CTRL_REQSEQ_SHIFT;

			pi->conn_state |= L2CAP_CONN_UNDER_REJ;



			goto send;

		}

	}

	return 0;



send:

	return l2cap_send_sframe(pi, tx_control);

}



static inline int l2cap_data_channel_sframe(struct sock *sk, u16 rx_control, struct sk_buff *skb)
@@ -2982,8 +2996,18 @@ static inline int l2cap_data_channel_sframe(struct sock *sk, u16 rx_control, str 
		l2cap_ertm_send(sk);

		break;



	case L2CAP_SUPER_RCV_NOT_READY:

	case L2CAP_SUPER_REJECT:

		pi->expected_ack_seq = __get_reqseq(rx_control);

		l2cap_drop_acked_frames(sk);



		sk->sk_send_head = TX_QUEUE(sk)->next;

		pi->next_tx_seq = pi->expected_ack_seq;



		l2cap_ertm_send(sk);



		break;



	case L2CAP_SUPER_RCV_NOT_READY:

	case L2CAP_SUPER_SELECT_REJECT:

		break;

	}
@@ -3030,6 +3054,11 @@ static inline int l2cap_data_channel(struct l2cap_conn *conn, u16 cid, struct sk 
		if (__is_sar_start(control))

			len -= 2;



		/*

		 * We can just drop the corrupted I-frame here.

		 * Receiver will miss it and start proper recovery

		 * procedures and ask retransmission.

		 */

		if (len > L2CAP_DEFAULT_MAX_PDU_SIZE)

			goto drop;