Bluetooth: Implement RejActioned flag

RejActioned is used to prevent retransmission when a entity is on the
WAIT_F state, i.e., waiting for a frame with F-bit set due local busy
condition or a expired retransmission timer. (When these two events raise
they send a frame with the Poll bit set and enters in the WAIT_F state to
wait for a frame with the Final bit set.)
The local entity doesn't send I-frames(the data frames) until the receipt
of a frame with F-bit set. When that happens it also set RejActioned to false.
RejActioned is a mandatory feature of ERTM spec.

Signed-off-by: Gustavo F. Padovan <gustavo@las.ic.unicamp.br>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

2 files changed, 36 insertions, 3 deletions

diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index 327eb57dab51..17a689f27a6a 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -374,6 +374,7 @@ struct l2cap_pinfo {
 #define L2CAP_CONN_SEND_PBIT       0x10
 #define L2CAP_CONN_REMOTE_BUSY     0x20
 #define L2CAP_CONN_LOCAL_BUSY      0x40
+#define L2CAP_CONN_REJ_ACT         0x80
 
 #define __mod_retrans_timer() mod_timer(&l2cap_pi(sk)->retrans_timer, \
                 jiffies +  msecs_to_jiffies(L2CAP_DEFAULT_RETRANS_TO));
diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c
index 78ab8811e5ef..73bda0ae41d6 100644
--- a/net/bluetooth/l2cap.c
+++ b/net/bluetooth/l2cap.c
@@ -3362,6 +3362,16 @@ expected:
                 return 0;
         }
 
+        if (rx_control & L2CAP_CTRL_FINAL) {
+                if (pi->conn_state & L2CAP_CONN_REJ_ACT)
+                        pi->conn_state &= ~L2CAP_CONN_REJ_ACT;
+                else {
+                        sk->sk_send_head = TX_QUEUE(sk)->next;
+                        pi->next_tx_seq = pi->expected_ack_seq;
+                        l2cap_ertm_send(sk);
+                }
+        }
+
         pi->buffer_seq = (pi->buffer_seq + 1) % 64;
 
         err = l2cap_sar_reassembly_sdu(sk, skb, rx_control);
@@ -3398,6 +3408,14 @@ static inline int l2cap_data_channel_sframe(struct sock *sk, u16 rx_control, str
                         pi->expected_ack_seq = tx_seq;
                         l2cap_drop_acked_frames(sk);
 
+                        if (pi->conn_state & L2CAP_CONN_REJ_ACT)
+                                pi->conn_state &= ~L2CAP_CONN_REJ_ACT;
+                        else {
+                                sk->sk_send_head = TX_QUEUE(sk)->next;
+                                pi->next_tx_seq = pi->expected_ack_seq;
+                                l2cap_ertm_send(sk);
+                        }
+
                         if (!(pi->conn_state & L2CAP_CONN_WAIT_F))
                                 break;
 
@@ -3425,10 +3443,24 @@ static inline int l2cap_data_channel_sframe(struct sock *sk, u16 rx_control, str
                 pi->expected_ack_seq = __get_reqseq(rx_control);
                 l2cap_drop_acked_frames(sk);
 
-                sk->sk_send_head = TX_QUEUE(sk)->next;
-                pi->next_tx_seq = pi->expected_ack_seq;
+                if (rx_control & L2CAP_CTRL_FINAL) {
+                        if (pi->conn_state & L2CAP_CONN_REJ_ACT)
+                                pi->conn_state &= ~L2CAP_CONN_REJ_ACT;
+                        else {
+                                sk->sk_send_head = TX_QUEUE(sk)->next;
+                                pi->next_tx_seq = pi->expected_ack_seq;
+                                l2cap_ertm_send(sk);
+                        }
+                } else {
+                        sk->sk_send_head = TX_QUEUE(sk)->next;
+                        pi->next_tx_seq = pi->expected_ack_seq;
+                        l2cap_ertm_send(sk);
 
-                l2cap_ertm_send(sk);
+                        if (pi->conn_state & L2CAP_CONN_WAIT_F) {
+                                pi->srej_save_reqseq = tx_seq;
+                                pi->conn_state |= L2CAP_CONN_REJ_ACT;
+                        }
+                }
 
                 break;