Bluetooth: L2CAP: Detect if remote is not able to use the whole MPS

If the remote is not able to fully utilize the MPS choosen recalculate
the credits based on the actual amount it is sending that way it can
still send packets of MTU size without credits dropping to 0.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 3fb2d757df88e126a2efd7cca1f297ebb2bd2edb..514899f7f0d4bfa12b8dcc7424a0379b9a87891c 100644 (file)
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -6787,6 +6787,16 @@ static int l2cap_le_data_rcv(struct l2cap_chan *chan, struct sk_buff *skb)
                chan->sdu_len = sdu_len;
                chan->sdu_last_frag = skb;
 
+               /* Detect if remote is not able to use the selected MPS */
+               if (skb->len + L2CAP_SDULEN_SIZE < chan->mps) {
+                       u16 mps_len = skb->len + L2CAP_SDULEN_SIZE;
+
+                       /* Adjust the number of credits */
+                       BT_DBG("chan->mps %u -> %u", chan->mps, mps_len);
+                       chan->mps = mps_len;
+                       l2cap_chan_le_send_credits(chan);
+               }
+
                return 0;
        }