Commit e90bac06 authored by Gustavo F. Padovan's avatar Gustavo F. Padovan Committed by Marcel Holtmann
Browse files

Bluetooth: Add support for Retransmission and Monitor Timers 



L2CAP uses retransmission and monitor timers to inquiry the other side
about unacked I-frames. After sending each I-frame we (re)start the
retransmission timer. If it expires, we start a monitor timer that send a
S-frame with P bit set and wait for S-frame with F bit set. If monitor
timer expires, try again, at a maximum of L2CAP_DEFAULT_MAX_TX.

Signed-off-by: default avatarGustavo F. Padovan <gustavo@las.ic.unicamp.br>
Signed-off-by: default avatarMarcel Holtmann <marcel@holtmann.org>
parent 30afb5b2

include/net/bluetooth/bluetooth.h

+1 −0
Original line number Diff line number Diff line
@@ -139,6 +139,7 @@ struct bt_skb_cb { 
	__u8 pkt_type;

	__u8 incoming;

	__u8 tx_seq;

	__u8 retries;

};

#define bt_cb(skb) ((struct bt_skb_cb *)((skb)->cb))

include/net/bluetooth/l2cap.h

+12 −3
Original line number Diff line number Diff line
@@ -31,9 +31,9 @@ 
#define L2CAP_DEFAULT_FLUSH_TO		0xffff

#define L2CAP_DEFAULT_TX_WINDOW		63

#define L2CAP_DEFAULT_NUM_TO_ACK        (L2CAP_DEFAULT_TX_WINDOW/5)

#define L2CAP_DEFAULT_MAX_RECEIVE	1

#define L2CAP_DEFAULT_RETRANS_TO	300    /* 300 milliseconds */

#define L2CAP_DEFAULT_MONITOR_TO	1000   /* 1 second */

#define L2CAP_DEFAULT_MAX_TX		3

#define L2CAP_DEFAULT_RETRANS_TO	1000    /* 1 second */

#define L2CAP_DEFAULT_MONITOR_TO	12000   /* 12 seconds */

#define L2CAP_DEFAULT_MAX_PDU_SIZE	672



#define L2CAP_CONN_TIMEOUT	(40000) /* 40 seconds */
@@ -318,6 +318,7 @@ struct l2cap_pinfo { 
	__u8		req_seq;

	__u8		expected_tx_seq;

	__u8		unacked_frames;

	__u8		retry_count;

	__u8		num_to_ack;

	__u16		sdu_len;

	__u16		partial_sdu_len;
@@ -333,6 +334,8 @@ struct l2cap_pinfo { 


	__le16		sport;



	struct timer_list	retrans_timer;

	struct timer_list	monitor_timer;

	struct sk_buff_head	tx_queue;

	struct l2cap_conn	*conn;

	struct sock		*next_c;
@@ -352,6 +355,12 @@ struct l2cap_pinfo { 


#define L2CAP_CONN_SAR_SDU         0x01

#define L2CAP_CONN_UNDER_REJ       0x02

#define L2CAP_CONN_WAIT_F          0x04



#define __mod_retrans_timer() mod_timer(&l2cap_pi(sk)->retrans_timer, \

		jiffies +  msecs_to_jiffies(L2CAP_DEFAULT_RETRANS_TO));

#define __mod_monitor_timer() mod_timer(&l2cap_pi(sk)->monitor_timer, \

		jiffies + msecs_to_jiffies(L2CAP_DEFAULT_MONITOR_TO));



static inline int l2cap_tx_window_full(struct sock *sk)

{

net/bluetooth/l2cap.c

+82 −4
Original line number Diff line number Diff line
@@ -1178,6 +1178,39 @@ static int l2cap_sock_getname(struct socket *sock, struct sockaddr *addr, int *l 
	return 0;

}



static void l2cap_monitor_timeout(unsigned long arg)

{

	struct sock *sk = (void *) arg;

	u16 control;



	if (l2cap_pi(sk)->retry_count >= l2cap_pi(sk)->remote_max_tx) {

		l2cap_send_disconn_req(l2cap_pi(sk)->conn, sk);

		return;

	}



	l2cap_pi(sk)->retry_count++;

	__mod_monitor_timer();



	control = L2CAP_CTRL_POLL;

	control |= L2CAP_SUPER_RCV_READY;

	l2cap_send_sframe(l2cap_pi(sk), control);

}



static void l2cap_retrans_timeout(unsigned long arg)

{

	struct sock *sk = (void *) arg;

	u16 control;



	l2cap_pi(sk)->retry_count = 1;

	__mod_monitor_timer();



	l2cap_pi(sk)->conn_state |= L2CAP_CONN_WAIT_F;



	control = L2CAP_CTRL_POLL;

	control |= L2CAP_SUPER_RCV_READY;

	l2cap_send_sframe(l2cap_pi(sk), control);

}



static void l2cap_drop_acked_frames(struct sock *sk)

{

	struct sk_buff *skb;
@@ -1192,6 +1225,9 @@ static void l2cap_drop_acked_frames(struct sock *sk) 
		l2cap_pi(sk)->unacked_frames--;

	}



	if (!l2cap_pi(sk)->unacked_frames)

		del_timer(&l2cap_pi(sk)->retrans_timer);



	return;

}
@@ -1216,19 +1252,32 @@ static int l2cap_ertm_send(struct sock *sk) 
	u16 control;

	int err;



	if (pi->conn_state & L2CAP_CONN_WAIT_F)

		return 0;



	while ((skb = sk->sk_send_head) && (!l2cap_tx_window_full(sk))) {

		tx_skb = skb_clone(skb, GFP_ATOMIC);



		if (pi->remote_max_tx &&

				bt_cb(skb)->retries == pi->remote_max_tx) {

			l2cap_send_disconn_req(pi->conn, sk);

			break;

		}



		bt_cb(skb)->retries++;



		control = get_unaligned_le16(tx_skb->data + L2CAP_HDR_SIZE);

		control |= (pi->req_seq << L2CAP_CTRL_REQSEQ_SHIFT)

				| (pi->next_tx_seq << L2CAP_CTRL_TXSEQ_SHIFT);

		put_unaligned_le16(control, tx_skb->data + L2CAP_HDR_SIZE);





		err = l2cap_do_send(sk, tx_skb);

		if (err < 0) {

			l2cap_send_disconn_req(pi->conn, sk);

			return err;

		}

		__mod_retrans_timer();



		bt_cb(skb)->tx_seq = pi->next_tx_seq;

		pi->next_tx_seq = (pi->next_tx_seq + 1) % 64;
@@ -1365,6 +1414,8 @@ static struct sk_buff *l2cap_create_ertm_pdu(struct sock *sk, struct msghdr *msg 
		kfree_skb(skb);

		return ERR_PTR(err);

	}



	bt_cb(skb)->retries = 0;

	return skb;

}
@@ -2058,7 +2109,7 @@ done: 
	case L2CAP_MODE_ERTM:

		rfc.mode            = L2CAP_MODE_ERTM;

		rfc.txwin_size      = L2CAP_DEFAULT_TX_WINDOW;

		rfc.max_transmit    = L2CAP_DEFAULT_MAX_RECEIVE;

		rfc.max_transmit    = L2CAP_DEFAULT_MAX_TX;

		rfc.retrans_timeout = 0;

		rfc.monitor_timeout = 0;

		rfc.max_pdu_size    = cpu_to_le16(L2CAP_DEFAULT_MAX_PDU_SIZE);
@@ -2553,6 +2604,12 @@ static inline int l2cap_config_req(struct l2cap_conn *conn, struct l2cap_cmd_hdr 
		l2cap_pi(sk)->next_tx_seq = 0;

		l2cap_pi(sk)->expected_ack_seq = 0;

		l2cap_pi(sk)->unacked_frames = 0;



		setup_timer(&l2cap_pi(sk)->retrans_timer,

				l2cap_retrans_timeout, (unsigned long) sk);

		setup_timer(&l2cap_pi(sk)->monitor_timer,

				l2cap_monitor_timeout, (unsigned long) sk);



		__skb_queue_head_init(TX_QUEUE(sk));

		l2cap_chan_ready(sk);

		goto unlock;
@@ -2662,6 +2719,8 @@ static inline int l2cap_disconnect_req(struct l2cap_conn *conn, struct l2cap_cmd 
	sk->sk_shutdown = SHUTDOWN_MASK;



	skb_queue_purge(TX_QUEUE(sk));

	del_timer(&l2cap_pi(sk)->retrans_timer);

	del_timer(&l2cap_pi(sk)->monitor_timer);



	l2cap_chan_del(sk, ECONNRESET);

	bh_unlock_sock(sk);
@@ -2686,6 +2745,8 @@ static inline int l2cap_disconnect_rsp(struct l2cap_conn *conn, struct l2cap_cmd 
		return 0;



	skb_queue_purge(TX_QUEUE(sk));

	del_timer(&l2cap_pi(sk)->retrans_timer);

	del_timer(&l2cap_pi(sk)->monitor_timer);



	l2cap_chan_del(sk, 0);

	bh_unlock_sock(sk);
@@ -2991,9 +3052,26 @@ static inline int l2cap_data_channel_sframe(struct sock *sk, u16 rx_control, str 


	switch (rx_control & L2CAP_CTRL_SUPERVISE) {

	case L2CAP_SUPER_RCV_READY:

		if (rx_control & L2CAP_CTRL_POLL) {

			u16 control = L2CAP_CTRL_FINAL;

			control |= L2CAP_SUPER_RCV_READY;

			l2cap_send_sframe(l2cap_pi(sk), control);

		} else if (rx_control & L2CAP_CTRL_FINAL) {

			if (!(pi->conn_state & L2CAP_CONN_WAIT_F))

				break;



			pi->conn_state &= ~L2CAP_CONN_WAIT_F;

			del_timer(&pi->monitor_timer);



			if (pi->unacked_frames > 0)

				__mod_retrans_timer();

		} else {

			pi->expected_ack_seq = __get_reqseq(rx_control);

			l2cap_drop_acked_frames(sk);

			if (pi->unacked_frames > 0)

				__mod_retrans_timer();

			l2cap_ertm_send(sk);

		}

		break;



	case L2CAP_SUPER_REJECT:

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