tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Packet RX/TX history data structures and routines for TFRC-based protocols.
3 *
4 * Copyright (c) 2007 The University of Aberdeen, Scotland, UK
5 * Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
6 *
7 * This code has been developed by the University of Waikato WAND
8 * research group. For further information please see http://www.wand.net.nz/
9 * or e-mail Ian McDonald - ian.mcdonald@jandi.co.nz
10 *
11 * This code also uses code from Lulea University, rereleased as GPL by its
12 * authors:
13 * Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
14 *
15 * Changes to meet Linux coding standards, to make it meet latest ccid3 draft
16 * and to make it work as a loadable module in the DCCP stack written by
17 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
18 *
19 * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
20 *
21 * This program is free software; you can redistribute it and/or modify
22 * it under the terms of the GNU General Public License as published by
23 * the Free Software Foundation; either version 2 of the License, or
24 * (at your option) any later version.
25 *
26 * This program is distributed in the hope that it will be useful,
27 * but WITHOUT ANY WARRANTY; without even the implied warranty of
28 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
29 * GNU General Public License for more details.
30 *
31 * You should have received a copy of the GNU General Public License
32 * along with this program; if not, write to the Free Software
33 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
34 */
35
36#ifndef _DCCP_PKT_HIST_
37#define _DCCP_PKT_HIST_
38
39#include <linux/list.h>
40#include <linux/slab.h>
41#include "tfrc.h"
42
43struct tfrc_tx_hist_entry;
44
45extern int tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno);
46extern void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp);
47extern u32 tfrc_tx_hist_rtt(struct tfrc_tx_hist_entry *head,
48 const u64 seqno, const ktime_t now);
49
50/* Subtraction a-b modulo-16, respects circular wrap-around */
51#define SUB16(a, b) (((a) + 16 - (b)) & 0xF)
52
53/* Number of packets to wait after a missing packet (RFC 4342, 6.1) */
54#define TFRC_NDUPACK 3
55
56/**
57 * tfrc_rx_hist_entry - Store information about a single received packet
58 * @tfrchrx_seqno: DCCP packet sequence number
59 * @tfrchrx_ccval: window counter value of packet (RFC 4342, 8.1)
60 * @tfrchrx_ndp: the NDP count (if any) of the packet
61 * @tfrchrx_tstamp: actual receive time of packet
62 */
63struct tfrc_rx_hist_entry {
64 u64 tfrchrx_seqno:48,
65 tfrchrx_ccval:4,
66 tfrchrx_type:4;
67 u64 tfrchrx_ndp:48;
68 ktime_t tfrchrx_tstamp;
69};
70
71/**
72 * tfrc_rx_hist - RX history structure for TFRC-based protocols
73 *
74 * @ring: Packet history for RTT sampling and loss detection
75 * @loss_count: Number of entries in circular history
76 * @loss_start: Movable index (for loss detection)
77 * @rtt_sample_prev: Used during RTT sampling, points to candidate entry
78 */
79struct tfrc_rx_hist {
80 struct tfrc_rx_hist_entry *ring[TFRC_NDUPACK + 1];
81 u8 loss_count:2,
82 loss_start:2;
83#define rtt_sample_prev loss_start
84};
85
86/**
87 * tfrc_rx_hist_index - index to reach n-th entry after loss_start
88 */
89static inline u8 tfrc_rx_hist_index(const struct tfrc_rx_hist *h, const u8 n)
90{
91 return (h->loss_start + n) & TFRC_NDUPACK;
92}
93
94/**
95 * tfrc_rx_hist_last_rcv - entry with highest-received-seqno so far
96 */
97static inline struct tfrc_rx_hist_entry *
98 tfrc_rx_hist_last_rcv(const struct tfrc_rx_hist *h)
99{
100 return h->ring[tfrc_rx_hist_index(h, h->loss_count)];
101}
102
103/**
104 * tfrc_rx_hist_entry - return the n-th history entry after loss_start
105 */
106static inline struct tfrc_rx_hist_entry *
107 tfrc_rx_hist_entry(const struct tfrc_rx_hist *h, const u8 n)
108{
109 return h->ring[tfrc_rx_hist_index(h, n)];
110}
111
112/**
113 * tfrc_rx_hist_loss_prev - entry with highest-received-seqno before loss was detected
114 */
115static inline struct tfrc_rx_hist_entry *
116 tfrc_rx_hist_loss_prev(const struct tfrc_rx_hist *h)
117{
118 return h->ring[h->loss_start];
119}
120
121/* indicate whether previously a packet was detected missing */
122static inline bool tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h)
123{
124 return h->loss_count > 0;
125}
126
127extern void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h,
128 const struct sk_buff *skb, const u64 ndp);
129
130extern int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb);
131
132struct tfrc_loss_hist;
133extern int tfrc_rx_handle_loss(struct tfrc_rx_hist *h,
134 struct tfrc_loss_hist *lh,
135 struct sk_buff *skb, const u64 ndp,
136 u32 (*first_li)(struct sock *sk),
137 struct sock *sk);
138extern u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h,
139 const struct sk_buff *skb);
140extern int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h);
141extern void tfrc_rx_hist_purge(struct tfrc_rx_hist *h);
142
143#endif /* _DCCP_PKT_HIST_ */