v4.19.13 snapshot.
diff --git a/include/linux/tfrc.h b/include/linux/tfrc.h
new file mode 100644
index 0000000..8a8462b
--- /dev/null
+++ b/include/linux/tfrc.h
@@ -0,0 +1,55 @@
+#ifndef _LINUX_TFRC_H_
+#define _LINUX_TFRC_H_
+/*
+ * TFRC - Data Structures for the TCP-Friendly Rate Control congestion
+ * control mechanism as specified in RFC 3448.
+ *
+ * Copyright (c) 2005 The University of Waikato, Hamilton, New Zealand.
+ * Copyright (c) 2005 Ian McDonald <iam4@cs.waikato.ac.nz>
+ * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ * Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+#include <linux/types.h>
+
+/** tfrc_rx_info - TFRC Receiver Data Structure
+ *
+ * @tfrcrx_x_recv: receiver estimate of sending rate (3.2.2)
+ * @tfrcrx_rtt: round-trip-time (communicated by sender)
+ * @tfrcrx_p: current estimate of loss event rate (3.2.2)
+ */
+struct tfrc_rx_info {
+ __u32 tfrcrx_x_recv;
+ __u32 tfrcrx_rtt;
+ __u32 tfrcrx_p;
+};
+
+/** tfrc_tx_info - TFRC Sender Data Structure
+ *
+ * @tfrctx_x: computed transmit rate (4.3 (4))
+ * @tfrctx_x_recv: receiver estimate of send rate (4.3)
+ * @tfrctx_x_calc: return value of throughput equation (3.1)
+ * @tfrctx_rtt: (moving average) estimate of RTT (4.3)
+ * @tfrctx_p: current loss event rate (5.4)
+ * @tfrctx_rto: estimate of RTO, equals 4*RTT (4.3)
+ * @tfrctx_ipi: inter-packet interval (4.6)
+ *
+ * Note: X and X_recv are both maintained in units of 64 * bytes/second. This
+ * enables a finer resolution of sending rates and avoids problems with
+ * integer arithmetic; u32 is not sufficient as scaling consumes 6 bits.
+ */
+struct tfrc_tx_info {
+ __u64 tfrctx_x;
+ __u64 tfrctx_x_recv;
+ __u32 tfrctx_x_calc;
+ __u32 tfrctx_rtt;
+ __u32 tfrctx_p;
+ __u32 tfrctx_rto;
+ __u32 tfrctx_ipi;
+};
+
+#endif /* _LINUX_TFRC_H_ */