Bluetooth: Dispatch internal callbacks using RX thread

This is safer now that bt_conn_create_pdu can return NULL when using
syswq which can prevent things like signalling of L2CAP and ATT layers.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

subsys/bluetooth/host/att.c

@@ -150,7 +150,7 @@ static int att_send(struct bt_conn *conn, struct net_buf *buf,
 	return 0;
 }
 
-static void att_pdu_sent(struct bt_conn *conn, void *user_data)
+void att_pdu_sent(struct bt_conn *conn, void *user_data)
 {
 	struct bt_att *att = att_get(conn);
 	struct net_buf *buf;
@@ -175,7 +175,7 @@ static void att_pdu_sent(struct bt_conn *conn, void *user_data)
 	k_sem_give(&att->tx_sem);
 }
 
-static void att_cfm_sent(struct bt_conn *conn, void *user_data)
+void att_cfm_sent(struct bt_conn *conn, void *user_data)
 {
 	struct bt_att *att = att_get(conn);
 
@@ -188,7 +188,7 @@ static void att_cfm_sent(struct bt_conn *conn, void *user_data)
 	att_pdu_sent(conn, user_data);
 }
 
-static void att_rsp_sent(struct bt_conn *conn, void *user_data)
+void att_rsp_sent(struct bt_conn *conn, void *user_data)
 {
 	struct bt_att *att = att_get(conn);
 
@@ -201,7 +201,7 @@ static void att_rsp_sent(struct bt_conn *conn, void *user_data)
 	att_pdu_sent(conn, user_data);
 }
 
-static void att_req_sent(struct bt_conn *conn, void *user_data)
+void att_req_sent(struct bt_conn *conn, void *user_data)
 {
 	struct bt_att *att = att_get(conn);
 
@@ -2048,6 +2048,9 @@ struct net_buf *bt_att_create_pdu(struct bt_conn *conn, u8_t op, size_t len)
 	}
 
 	buf = bt_l2cap_create_pdu(NULL, 0);
+	if (!buf) {
+		return NULL;
+	}
 
 	hdr = net_buf_add(buf, sizeof(*hdr));
 	hdr->code = op;

subsys/bluetooth/host/att_internal.h

@@ -236,6 +236,14 @@ struct bt_att_signed_write_cmd {
 	u8_t  value[0];
 } __packed;
 
+void att_pdu_sent(struct bt_conn *conn, void *user_data);
+
+void att_cfm_sent(struct bt_conn *conn, void *user_data);
+
+void att_rsp_sent(struct bt_conn *conn, void *user_data);
+
+void att_req_sent(struct bt_conn *conn, void *user_data);
+
 void bt_att_init(void);
 u16_t bt_att_get_mtu(struct bt_conn *conn);
 struct net_buf *bt_att_create_pdu(struct bt_conn *conn, u8_t op,

subsys/bluetooth/host/conn.c

@@ -1178,6 +1178,19 @@ int bt_conn_send_cb(struct bt_conn *conn, struct net_buf *buf,
 	return 0;
 }
 
+static bool conn_tx_internal(bt_conn_tx_cb_t cb)
+{
+	if (cb == att_pdu_sent || cb == att_cfm_sent || cb == att_rsp_sent ||
+#if defined(CONFIG_BT_L2CAP_DYNAMIC_CHANNEL)
+	    cb == l2cap_chan_sdu_sent ||
+#endif /* CONFIG_BT_L2CAP_DYNAMIC_CHANNEL */
+	    cb == att_req_sent) {
+		return true;
+	}
+
+	return false;
+}
+
 void bt_conn_notify_tx(struct bt_conn *conn)
 {
 	struct bt_conn_tx *tx;
@@ -1189,7 +1202,12 @@ void bt_conn_notify_tx(struct bt_conn *conn)
 
 		/* Only submit if there is a callback set */
 		if (tx->data.cb) {
-			k_work_submit(&tx->work);
+			/* Submit using RX thread if internal callback */
+			if (conn_tx_internal(tx->data.cb)) {
+				tx_notify_cb(&tx->work);
+			} else {
+				k_work_submit(&tx->work);
+			}
 		} else {
 			tx_free(tx);
 		}

subsys/bluetooth/host/l2cap.c

@@ -1128,7 +1128,7 @@ segment:
 	return seg;
 }
 
-static void l2cap_chan_sdu_sent(struct bt_conn *conn, void *user_data)
+void l2cap_chan_sdu_sent(struct bt_conn *conn, void *user_data)
 {
 	struct bt_l2cap_chan *chan = user_data;
 

subsys/bluetooth/host/l2cap_internal.h

@@ -222,6 +222,8 @@ struct bt_l2cap_br_fixed_chan {
 				.accept = _accept,		\
 			}
 
+void l2cap_chan_sdu_sent(struct bt_conn *conn, void *user_data);
+
 /* Notify L2CAP channels of a new connection */
 void bt_l2cap_connected(struct bt_conn *conn);