1 files changed, 27 insertions, 15 deletions

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 8a60db6261f7..3fb2d757df88 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -51,8 +51,6 @@ static u32 l2cap_feat_mask = L2CAP_FEAT_FIXED_CHAN | L2CAP_FEAT_UCD;
 static LIST_HEAD(chan_list);
 static DEFINE_RWLOCK(chan_list_lock);
 
-static u16 le_max_credits = L2CAP_LE_MAX_CREDITS;
-
 static struct sk_buff *l2cap_build_cmd(struct l2cap_conn *conn,
 				       u8 code, u8 ident, u16 dlen, void *data);
 static void l2cap_send_cmd(struct l2cap_conn *conn, u8 ident, u8 code, u16 len,
@@ -518,9 +516,10 @@ static void l2cap_le_flowctl_init(struct l2cap_chan *chan)
 	chan->sdu_last_frag = NULL;
 	chan->sdu_len = 0;
 	chan->tx_credits = 0;
-	chan->rx_credits = le_max_credits;
 	/* Derive MPS from connection MTU to stop HCI fragmentation */
 	chan->mps = min_t(u16, chan->imtu, chan->conn->mtu - L2CAP_HDR_SIZE);
+	/* Give enough credits for a full packet */
+	chan->rx_credits = (chan->imtu / chan->mps) + 1;
 
 	skb_queue_head_init(&chan->tx_q);
 }
@@ -6702,13 +6701,10 @@ static void l2cap_chan_le_send_credits(struct l2cap_chan *chan)
 	struct l2cap_le_credits pkt;
 	u16 return_credits;
 
-	/* We return more credits to the sender only after the amount of
-	 * credits falls below half of the initial amount.
-	 */
-	if (chan->rx_credits >= (le_max_credits + 1) / 2)
-		return;
+	return_credits = ((chan->imtu / chan->mps) + 1) - chan->rx_credits;
 
-	return_credits = le_max_credits - chan->rx_credits;
+	if (!return_credits)
+		return;
 
 	BT_DBG("chan %p returning %u credits to sender", chan, return_credits);
 
@@ -6722,6 +6718,21 @@ static void l2cap_chan_le_send_credits(struct l2cap_chan *chan)
 	l2cap_send_cmd(conn, chan->ident, L2CAP_LE_CREDITS, sizeof(pkt), &pkt);
 }
 
+static int l2cap_le_recv(struct l2cap_chan *chan, struct sk_buff *skb)
+{
+	int err;
+
+	BT_DBG("SDU reassemble complete: chan %p skb->len %u", chan, skb->len);
+
+	/* Wait recv to confirm reception before updating the credits */
+	err = chan->ops->recv(chan, skb);
+
+	/* Update credits whenever an SDU is received */
+	l2cap_chan_le_send_credits(chan);
+
+	return err;
+}
+
 static int l2cap_le_data_rcv(struct l2cap_chan *chan, struct sk_buff *skb)
 {
 	int err;
@@ -6740,7 +6751,11 @@ static int l2cap_le_data_rcv(struct l2cap_chan *chan, struct sk_buff *skb)
 	chan->rx_credits--;
 	BT_DBG("rx_credits %u -> %u", chan->rx_credits + 1, chan->rx_credits);
 
-	l2cap_chan_le_send_credits(chan);
+	/* Update if remote had run out of credits, this should only happens
+	 * if the remote is not using the entire MPS.
+	 */
+	if (!chan->rx_credits)
+		l2cap_chan_le_send_credits(chan);
 
 	err = 0;
 
@@ -6766,7 +6781,7 @@ static int l2cap_le_data_rcv(struct l2cap_chan *chan, struct sk_buff *skb)
 		}
 
 		if (skb->len == sdu_len)
-			return chan->ops->recv(chan, skb);
+			return l2cap_le_recv(chan, skb);
 
 		chan->sdu = skb;
 		chan->sdu_len = sdu_len;
@@ -6788,7 +6803,7 @@ static int l2cap_le_data_rcv(struct l2cap_chan *chan, struct sk_buff *skb)
 	skb = NULL;
 
 	if (chan->sdu->len == chan->sdu_len) {
-		err = chan->ops->recv(chan, chan->sdu);
+		err = l2cap_le_recv(chan, chan->sdu);
 		if (!err) {
 			chan->sdu = NULL;
 			chan->sdu_last_frag = NULL;
@@ -7647,9 +7662,6 @@ int __init l2cap_init(void)
 	l2cap_debugfs = debugfs_create_file("l2cap", 0444, bt_debugfs,
 					    NULL, &l2cap_debugfs_fops);
 
-	debugfs_create_u16("l2cap_le_max_credits", 0644, bt_debugfs,
-			   &le_max_credits);
-
 	return 0;
 }