Bluetooth: Refactor l2cap_send_ack

The function now encapsulates more of the logic to either immediately
send an ack if the transmit window is over 75% full, or wait for the
ack timer to expire if the transmit window is not full enough.  It is
also able to push out waiting iframes that can carry an
acknowledgement.

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 d795d15..f4d4eaf 100644 (file)
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -1772,28 +1772,54 @@ static int l2cap_retransmit_frames(struct l2cap_chan *chan)
        return ret;
 }
 
-static void __l2cap_send_ack(struct l2cap_chan *chan)
+static void l2cap_send_ack(struct l2cap_chan *chan)
 {
-       u32 control = 0;
+       struct l2cap_ctrl control;
+       u16 frames_to_ack = __seq_offset(chan, chan->buffer_seq,
+                                        chan->last_acked_seq);
+       int threshold;
 
-       control |= __set_reqseq(chan, chan->buffer_seq);
+       BT_DBG("chan %p last_acked_seq %d buffer_seq %d",
+              chan, chan->last_acked_seq, chan->buffer_seq);
 
-       if (test_bit(CONN_LOCAL_BUSY, &chan->conn_state)) {
-               control |= __set_ctrl_super(chan, L2CAP_SUPER_RNR);
-               set_bit(CONN_RNR_SENT, &chan->conn_state);
-               return;
-       }
+       memset(&control, 0, sizeof(control));
+       control.sframe = 1;
 
-       if (l2cap_ertm_send(chan) > 0)
-               return;
+       if (test_bit(CONN_LOCAL_BUSY, &chan->conn_state) &&
+           chan->rx_state == L2CAP_RX_STATE_RECV) {
+               __clear_ack_timer(chan);
+               control.super = L2CAP_SUPER_RNR;
+               control.reqseq = chan->buffer_seq;
+               l2cap_send_sframe(chan, &control);
+       } else {
+               if (!test_bit(CONN_REMOTE_BUSY, &chan->conn_state)) {
+                       l2cap_ertm_send(chan);
+                       /* If any i-frames were sent, they included an ack */
+                       if (chan->buffer_seq == chan->last_acked_seq)
+                               frames_to_ack = 0;
+               }
 
-       control |= __set_ctrl_super(chan, L2CAP_SUPER_RR);
-}
+               /* Ack now if the tx window is 3/4ths full.
+                * Calculate without mul or div
+                */
+               threshold = chan->tx_win;
+               threshold += threshold << 1;
+               threshold >>= 2;
+
+               BT_DBG("frames_to_ack %d, threshold %d", (int)frames_to_ack,
+                      threshold);
+
+               if (frames_to_ack >= threshold) {
+                       __clear_ack_timer(chan);
+                       control.super = L2CAP_SUPER_RR;
+                       control.reqseq = chan->buffer_seq;
+                       l2cap_send_sframe(chan, &control);
+                       frames_to_ack = 0;
+               }
 
-static void l2cap_send_ack(struct l2cap_chan *chan)
-{
-       __clear_ack_timer(chan);
-       __l2cap_send_ack(chan);
+               if (frames_to_ack)
+                       __set_ack_timer(chan);
+       }
 }
 
 static inline int l2cap_skbuff_fromiovec(struct l2cap_chan *chan,
@@ -2539,7 +2565,7 @@ static void l2cap_ack_timeout(struct work_struct *work)
 
        l2cap_chan_lock(chan);
 
-       __l2cap_send_ack(chan);
+       l2cap_send_ack(chan);
 
        l2cap_chan_unlock(chan);