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* Packet RX/TX history data structures and routines for TFRC-based protocols.
* Copyright (c) 2007 The University of Aberdeen, Scotland, UK
* Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
* This code has been developed by the University of Waikato WAND
* research group. For further information please see
* or e-mail Ian McDonald -
* This code also uses code from Lulea University, rereleased as GPL by its
* authors:
* Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
* Changes to meet Linux coding standards, to make it meet latest ccid3 draft
* and to make it work as a loadable module in the DCCP stack written by
* Arnaldo Carvalho de Melo <>.
* Copyright (c) 2005 Arnaldo Carvalho de Melo <>
* 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.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
#ifndef _DCCP_PKT_HIST_
#define _DCCP_PKT_HIST_
#include <linux/list.h>
#include <linux/slab.h>
#include "tfrc.h"
struct tfrc_tx_hist_entry;
extern int tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno);
extern void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp);
extern u32 tfrc_tx_hist_rtt(struct tfrc_tx_hist_entry *head,
const u64 seqno, const ktime_t now);
/* Subtraction a-b modulo-16, respects circular wrap-around */
#define SUB16(a, b) (((a) + 16 - (b)) & 0xF)
/* Number of packets to wait after a missing packet (RFC 4342, 6.1) */
#define TFRC_NDUPACK 3
* tfrc_rx_hist_entry - Store information about a single received packet
* @tfrchrx_seqno: DCCP packet sequence number
* @tfrchrx_ccval: window counter value of packet (RFC 4342, 8.1)
* @tfrchrx_ndp: the NDP count (if any) of the packet
* @tfrchrx_tstamp: actual receive time of packet
struct tfrc_rx_hist_entry {
u64 tfrchrx_seqno:48,
u64 tfrchrx_ndp:48;
ktime_t tfrchrx_tstamp;
* tfrc_rx_hist - RX history structure for TFRC-based protocols
* @ring: Packet history for RTT sampling and loss detection
* @loss_count: Number of entries in circular history
* @loss_start: Movable index (for loss detection)
* @rtt_sample_prev: Used during RTT sampling, points to candidate entry
struct tfrc_rx_hist {
struct tfrc_rx_hist_entry *ring[TFRC_NDUPACK + 1];
u8 loss_count:2,
#define rtt_sample_prev loss_start
* tfrc_rx_hist_index - index to reach n-th entry after loss_start
static inline u8 tfrc_rx_hist_index(const struct tfrc_rx_hist *h, const u8 n)
return (h->loss_start + n) & TFRC_NDUPACK;
* tfrc_rx_hist_last_rcv - entry with highest-received-seqno so far
static inline struct tfrc_rx_hist_entry *
tfrc_rx_hist_last_rcv(const struct tfrc_rx_hist *h)
return h->ring[tfrc_rx_hist_index(h, h->loss_count)];
* tfrc_rx_hist_entry - return the n-th history entry after loss_start
static inline struct tfrc_rx_hist_entry *
tfrc_rx_hist_entry(const struct tfrc_rx_hist *h, const u8 n)
return h->ring[tfrc_rx_hist_index(h, n)];
* tfrc_rx_hist_loss_prev - entry with highest-received-seqno before loss was detected
static inline struct tfrc_rx_hist_entry *
tfrc_rx_hist_loss_prev(const struct tfrc_rx_hist *h)
return h->ring[h->loss_start];
/* indicate whether previously a packet was detected missing */
static inline bool tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h)
return h->loss_count > 0;
extern void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h,
const struct sk_buff *skb, const u64 ndp);
extern int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb);
struct tfrc_loss_hist;
extern int tfrc_rx_handle_loss(struct tfrc_rx_hist *h,
struct tfrc_loss_hist *lh,
struct sk_buff *skb, const u64 ndp,
u32 (*first_li)(struct sock *sk),
struct sock *sk);
extern u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h,
const struct sk_buff *skb);
extern int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h);
extern void tfrc_rx_hist_purge(struct tfrc_rx_hist *h);
#endif /* _DCCP_PKT_HIST_ */