forked from Minki/linux
Bluetooth: Add the ERTM receive state machine
This adds a top-level state machine with handlers for two receive states defined in the ERTM spec, RECV and SREJ_SENT. The reqseq value of the incoming frame is also validated at the top level and a disconnection is forced if it is invalid. The actions for the RECV and SREJ_SENT states are implemented according to the state tables in the ERTM specification. Signed-off-by: Mat Martineau <mathewm@codeaurora.org> Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
This commit is contained in:
Mat Martineau
Johan Hedberg
parent
e31f763372
commit
d2a7ac5d5d
@ -1760,6 +1760,12 @@ static int l2cap_ertm_send(struct l2cap_chan *chan)
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return sent;
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}
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static void l2cap_retransmit_all(struct l2cap_chan *chan,
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struct l2cap_ctrl *control)
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{
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/* Placeholder */
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}
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static void l2cap_send_ack(struct l2cap_chan *chan)
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{
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struct l2cap_ctrl control;
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@ -2127,6 +2133,21 @@ int l2cap_chan_send(struct l2cap_chan *chan, struct msghdr *msg, size_t len,
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return err;
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}
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static void l2cap_send_srej(struct l2cap_chan *chan, u16 txseq)
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{
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/* Placeholder */
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}
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static void l2cap_send_srej_tail(struct l2cap_chan *chan)
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{
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/* Placeholder */
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}
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static void l2cap_send_srej_list(struct l2cap_chan *chan, u16 txseq)
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{
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/* Placeholder */
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}
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static void l2cap_process_reqseq(struct l2cap_chan *chan, u16 reqseq)
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{
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struct sk_buff *acked_skb;
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@ -4327,6 +4348,24 @@ void l2cap_chan_busy(struct l2cap_chan *chan, int busy)
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l2cap_tx(chan, 0, 0, event);
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}
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static int l2cap_rx_queued_iframes(struct l2cap_chan *chan)
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{
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/* Placeholder */
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return 0;
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}
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static void l2cap_handle_srej(struct l2cap_chan *chan,
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struct l2cap_ctrl *control)
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{
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/* Placeholder */
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}
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static void l2cap_handle_rej(struct l2cap_chan *chan,
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struct l2cap_ctrl *control)
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{
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/* Placeholder */
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}
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static u8 l2cap_classify_txseq(struct l2cap_chan *chan, u16 txseq)
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{
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BT_DBG("chan %p, txseq %d", chan, txseq);
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@ -4414,11 +4453,323 @@ static u8 l2cap_classify_txseq(struct l2cap_chan *chan, u16 txseq)
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}
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}
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static int l2cap_rx_state_recv(struct l2cap_chan *chan,
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struct l2cap_ctrl *control,
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struct sk_buff *skb, u8 event)
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{
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int err = 0;
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bool skb_in_use = 0;
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BT_DBG("chan %p, control %p, skb %p, event %d", chan, control, skb,
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event);
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switch (event) {
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case L2CAP_EV_RECV_IFRAME:
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switch (l2cap_classify_txseq(chan, control->txseq)) {
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case L2CAP_TXSEQ_EXPECTED:
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l2cap_pass_to_tx(chan, control);
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if (test_bit(CONN_LOCAL_BUSY, &chan->conn_state)) {
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BT_DBG("Busy, discarding expected seq %d",
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control->txseq);
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break;
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}
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chan->expected_tx_seq = __next_seq(chan,
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control->txseq);
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chan->buffer_seq = chan->expected_tx_seq;
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skb_in_use = 1;
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err = l2cap_reassemble_sdu(chan, skb, control);
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if (err)
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break;
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if (control->final) {
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if (!test_and_clear_bit(CONN_REJ_ACT,
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&chan->conn_state)) {
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control->final = 0;
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l2cap_retransmit_all(chan, control);
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l2cap_ertm_send(chan);
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}
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}
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if (!test_bit(CONN_LOCAL_BUSY, &chan->conn_state))
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l2cap_send_ack(chan);
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break;
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case L2CAP_TXSEQ_UNEXPECTED:
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l2cap_pass_to_tx(chan, control);
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/* Can't issue SREJ frames in the local busy state.
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* Drop this frame, it will be seen as missing
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* when local busy is exited.
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*/
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if (test_bit(CONN_LOCAL_BUSY, &chan->conn_state)) {
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BT_DBG("Busy, discarding unexpected seq %d",
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control->txseq);
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break;
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}
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/* There was a gap in the sequence, so an SREJ
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* must be sent for each missing frame. The
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* current frame is stored for later use.
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*/
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skb_queue_tail(&chan->srej_q, skb);
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skb_in_use = 1;
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BT_DBG("Queued %p (queue len %d)", skb,
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skb_queue_len(&chan->srej_q));
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clear_bit(CONN_SREJ_ACT, &chan->conn_state);
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l2cap_seq_list_clear(&chan->srej_list);
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l2cap_send_srej(chan, control->txseq);
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chan->rx_state = L2CAP_RX_STATE_SREJ_SENT;
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break;
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case L2CAP_TXSEQ_DUPLICATE:
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l2cap_pass_to_tx(chan, control);
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break;
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case L2CAP_TXSEQ_INVALID_IGNORE:
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break;
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case L2CAP_TXSEQ_INVALID:
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default:
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l2cap_send_disconn_req(chan->conn, chan,
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ECONNRESET);
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break;
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}
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break;
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case L2CAP_EV_RECV_RR:
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l2cap_pass_to_tx(chan, control);
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if (control->final) {
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clear_bit(CONN_REMOTE_BUSY, &chan->conn_state);
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if (!test_and_clear_bit(CONN_REJ_ACT,
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&chan->conn_state)) {
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control->final = 0;
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l2cap_retransmit_all(chan, control);
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}
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l2cap_ertm_send(chan);
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} else if (control->poll) {
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l2cap_send_i_or_rr_or_rnr(chan);
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} else {
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if (test_and_clear_bit(CONN_REMOTE_BUSY,
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&chan->conn_state) &&
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chan->unacked_frames)
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__set_retrans_timer(chan);
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l2cap_ertm_send(chan);
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}
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break;
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case L2CAP_EV_RECV_RNR:
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set_bit(CONN_REMOTE_BUSY, &chan->conn_state);
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l2cap_pass_to_tx(chan, control);
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if (control && control->poll) {
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set_bit(CONN_SEND_FBIT, &chan->conn_state);
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l2cap_send_rr_or_rnr(chan, 0);
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}
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__clear_retrans_timer(chan);
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l2cap_seq_list_clear(&chan->retrans_list);
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break;
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case L2CAP_EV_RECV_REJ:
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l2cap_handle_rej(chan, control);
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break;
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case L2CAP_EV_RECV_SREJ:
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l2cap_handle_srej(chan, control);
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break;
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default:
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break;
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}
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if (skb && !skb_in_use) {
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BT_DBG("Freeing %p", skb);
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kfree_skb(skb);
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}
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return err;
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}
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static int l2cap_rx_state_srej_sent(struct l2cap_chan *chan,
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struct l2cap_ctrl *control,
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struct sk_buff *skb, u8 event)
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{
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int err = 0;
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u16 txseq = control->txseq;
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bool skb_in_use = 0;
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BT_DBG("chan %p, control %p, skb %p, event %d", chan, control, skb,
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event);
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switch (event) {
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case L2CAP_EV_RECV_IFRAME:
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switch (l2cap_classify_txseq(chan, txseq)) {
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case L2CAP_TXSEQ_EXPECTED:
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/* Keep frame for reassembly later */
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l2cap_pass_to_tx(chan, control);
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skb_queue_tail(&chan->srej_q, skb);
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skb_in_use = 1;
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BT_DBG("Queued %p (queue len %d)", skb,
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skb_queue_len(&chan->srej_q));
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chan->expected_tx_seq = __next_seq(chan, txseq);
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break;
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case L2CAP_TXSEQ_EXPECTED_SREJ:
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l2cap_seq_list_pop(&chan->srej_list);
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l2cap_pass_to_tx(chan, control);
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skb_queue_tail(&chan->srej_q, skb);
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skb_in_use = 1;
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BT_DBG("Queued %p (queue len %d)", skb,
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skb_queue_len(&chan->srej_q));
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err = l2cap_rx_queued_iframes(chan);
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if (err)
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break;
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break;
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case L2CAP_TXSEQ_UNEXPECTED:
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/* Got a frame that can't be reassembled yet.
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* Save it for later, and send SREJs to cover
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* the missing frames.
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*/
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skb_queue_tail(&chan->srej_q, skb);
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skb_in_use = 1;
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BT_DBG("Queued %p (queue len %d)", skb,
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skb_queue_len(&chan->srej_q));
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l2cap_pass_to_tx(chan, control);
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l2cap_send_srej(chan, control->txseq);
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break;
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case L2CAP_TXSEQ_UNEXPECTED_SREJ:
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/* This frame was requested with an SREJ, but
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* some expected retransmitted frames are
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* missing. Request retransmission of missing
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* SREJ'd frames.
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*/
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skb_queue_tail(&chan->srej_q, skb);
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skb_in_use = 1;
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BT_DBG("Queued %p (queue len %d)", skb,
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skb_queue_len(&chan->srej_q));
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l2cap_pass_to_tx(chan, control);
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l2cap_send_srej_list(chan, control->txseq);
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break;
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case L2CAP_TXSEQ_DUPLICATE_SREJ:
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/* We've already queued this frame. Drop this copy. */
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l2cap_pass_to_tx(chan, control);
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break;
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case L2CAP_TXSEQ_DUPLICATE:
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/* Expecting a later sequence number, so this frame
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* was already received. Ignore it completely.
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*/
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break;
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case L2CAP_TXSEQ_INVALID_IGNORE:
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break;
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case L2CAP_TXSEQ_INVALID:
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default:
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l2cap_send_disconn_req(chan->conn, chan,
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ECONNRESET);
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break;
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}
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break;
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case L2CAP_EV_RECV_RR:
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l2cap_pass_to_tx(chan, control);
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if (control->final) {
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clear_bit(CONN_REMOTE_BUSY, &chan->conn_state);
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if (!test_and_clear_bit(CONN_REJ_ACT,
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&chan->conn_state)) {
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control->final = 0;
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l2cap_retransmit_all(chan, control);
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}
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l2cap_ertm_send(chan);
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} else if (control->poll) {
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if (test_and_clear_bit(CONN_REMOTE_BUSY,
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&chan->conn_state) &&
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chan->unacked_frames) {
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__set_retrans_timer(chan);
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}
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set_bit(CONN_SEND_FBIT, &chan->conn_state);
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l2cap_send_srej_tail(chan);
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} else {
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if (test_and_clear_bit(CONN_REMOTE_BUSY,
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&chan->conn_state) &&
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chan->unacked_frames)
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__set_retrans_timer(chan);
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l2cap_send_ack(chan);
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}
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break;
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case L2CAP_EV_RECV_RNR:
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set_bit(CONN_REMOTE_BUSY, &chan->conn_state);
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l2cap_pass_to_tx(chan, control);
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if (control->poll) {
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l2cap_send_srej_tail(chan);
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} else {
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struct l2cap_ctrl rr_control;
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memset(&rr_control, 0, sizeof(rr_control));
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rr_control.sframe = 1;
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rr_control.super = L2CAP_SUPER_RR;
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rr_control.reqseq = chan->buffer_seq;
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l2cap_send_sframe(chan, &rr_control);
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}
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break;
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case L2CAP_EV_RECV_REJ:
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l2cap_handle_rej(chan, control);
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break;
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case L2CAP_EV_RECV_SREJ:
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l2cap_handle_srej(chan, control);
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break;
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}
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if (skb && !skb_in_use) {
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BT_DBG("Freeing %p", skb);
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kfree_skb(skb);
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}
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return err;
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}
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static bool __valid_reqseq(struct l2cap_chan *chan, u16 reqseq)
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{
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/* Make sure reqseq is for a packet that has been sent but not acked */
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u16 unacked;
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unacked = __seq_offset(chan, chan->next_tx_seq, chan->expected_ack_seq);
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return __seq_offset(chan, chan->next_tx_seq, reqseq) <= unacked;
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}
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static int l2cap_rx(struct l2cap_chan *chan, struct l2cap_ctrl *control,
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struct sk_buff *skb, u8 event)
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{
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/* Placeholder */
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return -ENOTSUPP;
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int err = 0;
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BT_DBG("chan %p, control %p, skb %p, event %d, state %d", chan,
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control, skb, event, chan->rx_state);
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if (__valid_reqseq(chan, control->reqseq)) {
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switch (chan->rx_state) {
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case L2CAP_RX_STATE_RECV:
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err = l2cap_rx_state_recv(chan, control, skb, event);
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break;
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case L2CAP_RX_STATE_SREJ_SENT:
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err = l2cap_rx_state_srej_sent(chan, control, skb,
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event);
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break;
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default:
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/* shut it down */
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break;
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}
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} else {
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BT_DBG("Invalid reqseq %d (next_tx_seq %d, expected_ack_seq %d",
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control->reqseq, chan->next_tx_seq,
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chan->expected_ack_seq);
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l2cap_send_disconn_req(chan->conn, chan, ECONNRESET);
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}
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return err;
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}
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static int l2cap_stream_rx(struct l2cap_chan *chan, struct l2cap_ctrl *control,
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