Re: [PATCH 02/25] Bluetooth: Add a new L2CAP ERTM transmit state machine.

[Gustavo Padovan <gustavo@padovan.org>]

Hi Mat,

* Mat Martineau <mathewm@codeaurora.org> [2012-05-17 20:53:32 -0700]:

> This implements a top-level transmit state machine with handlers for
> the two ERTM states defined in the specification: XMIT and WAIT_F.
> 
> The state machine accepts an event and, optionally, a list of skbs to
> transmit.  In addition to data transmission, the local busy state can
> be modified, acks are processed, and monitor and retransmit timeouts
> are handled.  This mirrors the structure of the state tables in the
> spec.
> 
> Signed-off-by: Mat Martineau <mathewm@codeaurora.org>
> ---
>  net/bluetooth/l2cap_core.c |  254 ++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 246 insertions(+), 8 deletions(-)
> 
> diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> index 6557367..a131403 100644
> --- a/net/bluetooth/l2cap_core.c
> +++ b/net/bluetooth/l2cap_core.c
> @@ -73,6 +73,9 @@ static int l2cap_build_conf_req(struct l2cap_chan *chan, void *data);
>  static void l2cap_send_disconn_req(struct l2cap_conn *conn,
>  				   struct l2cap_chan *chan, int err);
>  
> +static int l2cap_tx(struct l2cap_chan *chan, struct l2cap_ctrl *control,
> +		    struct sk_buff_head *skbs, u8 event);
> +
>  /* ---- L2CAP channels ---- */
>  
>  static struct l2cap_chan *__l2cap_get_chan_by_dcid(struct l2cap_conn *conn, u16 cid)
> @@ -224,6 +227,19 @@ static inline void l2cap_chan_set_err(struct l2cap_chan *chan, int err)
>  	release_sock(sk);
>  }
>  
> +static struct sk_buff *l2cap_ertm_seq_in_queue(struct sk_buff_head *head,
> +					       u16 seq)
> +{
> +	struct sk_buff *skb;
> +
> +	skb_queue_walk(head, skb) {
> +		if (bt_cb(skb)->control.txseq == seq)
> +			return skb;
> +	}
> +
> +	return NULL;
> +}
> +
>  /* ---- L2CAP sequence number lists ---- */
>  
>  /* For ERTM, ordered lists of sequence numbers must be tracked for
> @@ -2117,16 +2133,15 @@ int l2cap_chan_send(struct l2cap_chan *chan, struct msghdr *msg, size_t len,
>  		if (err)
>  			break;
>  
> -		if (chan->mode == L2CAP_MODE_ERTM && chan->tx_send_head == NULL)
> -			chan->tx_send_head = seg_queue.next;
> -		skb_queue_splice_tail_init(&seg_queue, &chan->tx_q);
> -
> -		if (chan->mode == L2CAP_MODE_ERTM)
> -			err = l2cap_ertm_send(chan);
> -		else
> +		if (chan->mode == L2CAP_MODE_ERTM) {
> +			err = l2cap_tx(chan, 0, &seg_queue,
> +				       L2CAP_EV_DATA_REQUEST);
> +		} else {
> +			skb_queue_splice_tail_init(&seg_queue, &chan->tx_q);
>  			l2cap_streaming_send(chan);
> +		}
>  
> -		if (err >= 0)
> +		if (!err)
>  			err = len;
>  
>  		/* If the skbs were not queued for sending, they'll still be in
> @@ -2143,6 +2158,229 @@ int l2cap_chan_send(struct l2cap_chan *chan, struct msghdr *msg, size_t len,
>  	return err;
>  }
>  
> +static void l2cap_process_reqseq(struct l2cap_chan *chan, u16 reqseq)
> +{
> +	struct sk_buff *acked_skb;
> +	u16 ackseq;
> +
> +	BT_DBG("chan %p, reqseq %d", chan, reqseq);
> +
> +	if (chan->unacked_frames == 0 || reqseq == chan->expected_ack_seq)
> +		return;
> +
> +	BT_DBG("expected_ack_seq %d, unacked_frames %d",
> +	       chan->expected_ack_seq, chan->unacked_frames);
> +
> +	for (ackseq = chan->expected_ack_seq; ackseq != reqseq;
> +	     ackseq = __next_seq(chan, ackseq)) {
> +
> +		acked_skb = l2cap_ertm_seq_in_queue(&chan->tx_q, ackseq);
> +		if (acked_skb) {
> +			skb_unlink(acked_skb, &chan->tx_q);
> +			kfree_skb(acked_skb);
> +			chan->unacked_frames--;
> +		}
> +	}
> +
> +	chan->expected_ack_seq = reqseq;
> +
> +	if (chan->unacked_frames == 0)
> +		__clear_retrans_timer(chan);
> +
> +	BT_DBG("unacked_frames %d", (int) chan->unacked_frames);
> +}
> +
> +static void l2cap_abort_rx_srej_sent(struct l2cap_chan *chan)
> +{
> +	BT_DBG("chan %p", chan);
> +
> +	chan->expected_tx_seq = chan->buffer_seq;
> +	l2cap_seq_list_clear(&chan->srej_list);
> +	skb_queue_purge(&chan->srej_q);
> +	chan->rx_state = L2CAP_RX_STATE_RECV;
> +}
> +
> +static int l2cap_tx_state_xmit(struct l2cap_chan *chan,
> +			       struct l2cap_ctrl *control,
> +			       struct sk_buff_head *skbs, u8 event)
> +{
> +	int err = 0;
> +
> +	BT_DBG("chan %p, control %p, skbs %p, event %d", chan, control, skbs,
> +	       event);
> +
> +	switch (event) {
> +	case L2CAP_EV_DATA_REQUEST:
> +		if (chan->tx_send_head == NULL)
> +			chan->tx_send_head = skb_peek(skbs);
> +
> +		skb_queue_splice_tail_init(skbs, &chan->tx_q);
> +		l2cap_ertm_send(chan);
> +		break;
> +	case L2CAP_EV_LOCAL_BUSY_DETECTED:
> +		BT_DBG("Enter LOCAL_BUSY");
> +		set_bit(CONN_LOCAL_BUSY, &chan->conn_state);
> +
> +		if (chan->rx_state == L2CAP_RX_STATE_SREJ_SENT) {
> +			/* The SREJ_SENT state must be aborted if we are to
> +			 * enter the LOCAL_BUSY state.
> +			 */
> +			l2cap_abort_rx_srej_sent(chan);
> +		}
> +
> +		l2cap_send_ack(chan);
> +
> +		break;
> +	case L2CAP_EV_LOCAL_BUSY_CLEAR:
> +		BT_DBG("Exit LOCAL_BUSY");
> +		clear_bit(CONN_LOCAL_BUSY, &chan->conn_state);
> +
> +		if (test_bit(CONN_RNR_SENT, &chan->conn_state)) {
> +			struct l2cap_ctrl local_control;
> +
> +			memset(&local_control, 0, sizeof(local_control));
> +			local_control.sframe = 1;
> +			local_control.super = L2CAP_SUPER_RR;
> +			local_control.poll = 1;
> +			local_control.reqseq = chan->buffer_seq;

You are not using local_control anywhere? Should it be removed, or other patch
in this patchset uses it?

	Gustavo