Bluetooth: Consolidate common receive code for ERTM and streaming mode

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>

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index c7bf613..a84d337 100644 (file)
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -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);
        }
 }
 
@@ -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)
@@ -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;
@@ -4891,9 +4928,6 @@ drop:
 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) {
@@ -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: