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Bluetooth: Consolidate common receive code for ERTM and streaming mode
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Creates a new l2cap_data_rcv function that combines previous code from
l2cap_ertm_data_rcv and l2cap_data_channel.  This reduces duplicate
code for streaming mode, and sets up a framework for the ERTM receive
state machine.

Signed-off-by: Mat Martineau <mathewm@codeaurora.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
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Mat Martineau authored and Johan Hedberg committed Jun 5, 2012
1 parent a67d7f6 commit cec8ab6
Showing 1 changed file with 62 additions and 64 deletions.
126 changes: 62 additions & 64 deletions net/bluetooth/l2cap_core.c
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Original file line number Diff line number Diff line change
Expand Up @@ -791,9 +791,11 @@ static inline void __unpack_control(struct l2cap_chan *chan,
if (test_bit(FLAG_EXT_CTRL, &chan->flags)) {
__unpack_extended_control(get_unaligned_le32(skb->data),
&bt_cb(skb)->control);
skb_pull(skb, L2CAP_EXT_CTRL_SIZE);
} else {
__unpack_enhanced_control(get_unaligned_le16(skb->data),
&bt_cb(skb)->control);
skb_pull(skb, L2CAP_ENH_CTRL_SIZE);
}
}

Expand Down Expand Up @@ -4820,27 +4822,39 @@ static inline int l2cap_data_channel_sframe(struct l2cap_chan *chan, u32 rx_cont
return 0;
}

static int l2cap_ertm_data_rcv(struct l2cap_chan *chan, struct sk_buff *skb)
static int l2cap_rx(struct l2cap_chan *chan, struct l2cap_ctrl *control,
struct sk_buff *skb, u8 event)
{
u32 control;
u16 req_seq;
int len, next_tx_seq_offset, req_seq_offset;
/* Placeholder */
return -ENOTSUPP;
}

static int l2cap_stream_rx(struct l2cap_chan *chan, struct l2cap_ctrl *control,
struct sk_buff *skb)
{
/* Placeholder */
return -ENOTSUPP;
}

static int l2cap_data_rcv(struct l2cap_chan *chan, struct sk_buff *skb)
{
struct l2cap_ctrl *control = &bt_cb(skb)->control;
u16 len;
u8 event;

__unpack_control(chan, skb);

control = __get_control(chan, skb->data);
skb_pull(skb, __ctrl_size(chan));
len = skb->len;

/*
* We can just drop the corrupted I-frame here.
* Receiver will miss it and start proper recovery
* procedures and ask retransmission.
* procedures and ask for retransmission.
*/
if (l2cap_check_fcs(chan, skb))
goto drop;

if (__is_sar_start(chan, control) && !__is_sframe(chan, control))
if (!control->sframe && control->sar == L2CAP_SAR_START)
len -= L2CAP_SDULEN_SIZE;

if (chan->fcs == L2CAP_FCS_CRC16)
Expand All @@ -4851,34 +4865,57 @@ static int l2cap_ertm_data_rcv(struct l2cap_chan *chan, struct sk_buff *skb)
goto drop;
}

req_seq = __get_reqseq(chan, control);

req_seq_offset = __seq_offset(chan, req_seq, chan->expected_ack_seq);

next_tx_seq_offset = __seq_offset(chan, chan->next_tx_seq,
chan->expected_ack_seq);
if (!control->sframe) {
int err;

/* check for invalid req-seq */
if (req_seq_offset > next_tx_seq_offset) {
l2cap_send_disconn_req(chan->conn, chan, ECONNRESET);
goto drop;
}
BT_DBG("iframe sar %d, reqseq %d, final %d, txseq %d",
control->sar, control->reqseq, control->final,
control->txseq);

if (!__is_sframe(chan, control)) {
if (len < 0) {
l2cap_send_disconn_req(chan->conn, chan, ECONNRESET);
/* Validate F-bit - F=0 always valid, F=1 only
* valid in TX WAIT_F
*/
if (control->final && chan->tx_state != L2CAP_TX_STATE_WAIT_F)
goto drop;

if (chan->mode != L2CAP_MODE_STREAMING) {
event = L2CAP_EV_RECV_IFRAME;
err = l2cap_rx(chan, control, skb, event);
} else {
err = l2cap_stream_rx(chan, control, skb);
}

l2cap_data_channel_iframe(chan, control, skb);
if (err)
l2cap_send_disconn_req(chan->conn, chan,
ECONNRESET);
} else {
const u8 rx_func_to_event[4] = {
L2CAP_EV_RECV_RR, L2CAP_EV_RECV_REJ,
L2CAP_EV_RECV_RNR, L2CAP_EV_RECV_SREJ
};

/* Only I-frames are expected in streaming mode */
if (chan->mode == L2CAP_MODE_STREAMING)
goto drop;

BT_DBG("sframe reqseq %d, final %d, poll %d, super %d",
control->reqseq, control->final, control->poll,
control->super);

if (len != 0) {
BT_ERR("%d", len);
l2cap_send_disconn_req(chan->conn, chan, ECONNRESET);
goto drop;
}

l2cap_data_channel_sframe(chan, control, skb);
/* Validate F and P bits */
if (control->final && (control->poll ||
chan->tx_state != L2CAP_TX_STATE_WAIT_F))
goto drop;

event = rx_func_to_event[control->super];
if (l2cap_rx(chan, control, skb, event))
l2cap_send_disconn_req(chan->conn, chan, ECONNRESET);
}

return 0;
Expand All @@ -4891,9 +4928,6 @@ static int l2cap_ertm_data_rcv(struct l2cap_chan *chan, struct sk_buff *skb)
static inline int l2cap_data_channel(struct l2cap_conn *conn, u16 cid, struct sk_buff *skb)
{
struct l2cap_chan *chan;
u32 control;
u16 tx_seq;
int len;

chan = l2cap_get_chan_by_scid(conn, cid);
if (!chan) {
Expand Down Expand Up @@ -4923,44 +4957,8 @@ static inline int l2cap_data_channel(struct l2cap_conn *conn, u16 cid, struct sk
break;

case L2CAP_MODE_ERTM:
l2cap_ertm_data_rcv(chan, skb);

goto done;

case L2CAP_MODE_STREAMING:
control = __get_control(chan, skb->data);
skb_pull(skb, __ctrl_size(chan));
len = skb->len;

if (l2cap_check_fcs(chan, skb))
goto drop;

if (__is_sar_start(chan, control))
len -= L2CAP_SDULEN_SIZE;

if (chan->fcs == L2CAP_FCS_CRC16)
len -= L2CAP_FCS_SIZE;

if (len > chan->mps || len < 0 || __is_sframe(chan, control))
goto drop;

tx_seq = __get_txseq(chan, control);

if (chan->expected_tx_seq != tx_seq) {
/* Frame(s) missing - must discard partial SDU */
kfree_skb(chan->sdu);
chan->sdu = NULL;
chan->sdu_last_frag = NULL;
chan->sdu_len = 0;

/* TODO: Notify userland of missing data */
}

chan->expected_tx_seq = __next_seq(chan, tx_seq);

if (l2cap_reassemble_sdu(chan, skb, control) == -EMSGSIZE)
l2cap_send_disconn_req(chan->conn, chan, ECONNRESET);

l2cap_data_rcv(chan, skb);
goto done;

default:
Expand Down

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