1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3 * Packet RX/TX history data structures and routines for TFRC-based protocols.
4 *
5 * Copyright (c) 2007 The University of Aberdeen, Scotland, UK
6 * Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
7 *
8 * This code has been developed by the University of Waikato WAND
9 * research group. For further information please see https://www.wand.net.nz/
10 * or e-mail Ian McDonald - ian.mcdonald@jandi.co.nz
11 *
12 * This code also uses code from Lulea University, rereleased as GPL by its
13 * authors:
14 * Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
15 *
16 * Changes to meet Linux coding standards, to make it meet latest ccid3 draft
17 * and to make it work as a loadable module in the DCCP stack written by
18 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
19 *
20 * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
21 */
22
23 #ifndef _DCCP_PKT_HIST_
24 #define _DCCP_PKT_HIST_
25
26 #include <linux/list.h>
27 #include <linux/slab.h>
28 #include "tfrc.h"
29
30 /**
31 * tfrc_tx_hist_entry - Simple singly-linked TX history list
32 * @next: next oldest entry (LIFO order)
33 * @seqno: sequence number of this entry
34 * @stamp: send time of packet with sequence number @seqno
35 */
36 struct tfrc_tx_hist_entry {
37 struct tfrc_tx_hist_entry *next;
38 u64 seqno;
39 ktime_t stamp;
40 };
41
42 static inline struct tfrc_tx_hist_entry *
43 tfrc_tx_hist_find_entry(struct tfrc_tx_hist_entry *head, u64 seqno)
44 {
45 while (head != NULL && head->seqno != seqno)
46 head = head->next;
47 return head;
48 }
49
50 int tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno);
51 void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp);
52
53 /* Subtraction a-b modulo-16, respects circular wrap-around */
54 #define SUB16(a, b) (((a) + 16 - (b)) & 0xF)
55
56 /* Number of packets to wait after a missing packet (RFC 4342, 6.1) */
57 #define TFRC_NDUPACK 3
58
59 /**
60 * tfrc_rx_hist_entry - Store information about a single received packet
61 * @tfrchrx_seqno: DCCP packet sequence number
62 * @tfrchrx_ccval: window counter value of packet (RFC 4342, 8.1)
63 * @tfrchrx_ndp: the NDP count (if any) of the packet
64 * @tfrchrx_tstamp: actual receive time of packet
65 */
66 struct tfrc_rx_hist_entry {
67 u64 tfrchrx_seqno:48,
68 tfrchrx_ccval:4,
69 tfrchrx_type:4;
70 u64 tfrchrx_ndp:48;
71 ktime_t tfrchrx_tstamp;
72 };
73
74 /**
75 * tfrc_rx_hist - RX history structure for TFRC-based protocols
76 * @ring: Packet history for RTT sampling and loss detection
77 * @loss_count: Number of entries in circular history
78 * @loss_start: Movable index (for loss detection)
79 * @rtt_sample_prev: Used during RTT sampling, points to candidate entry
80 */
81 struct tfrc_rx_hist {
82 struct tfrc_rx_hist_entry *ring[TFRC_NDUPACK + 1];
83 u8 loss_count:2,
84 loss_start:2;
85 #define rtt_sample_prev loss_start
86 };
87
88 /**
89 * tfrc_rx_hist_index - index to reach n-th entry after loss_start
90 */
91 static inline u8 tfrc_rx_hist_index(const struct tfrc_rx_hist *h, const u8 n)
92 {
93 return (h->loss_start + n) & TFRC_NDUPACK;
94 }
95
96 /**
97 * tfrc_rx_hist_last_rcv - entry with highest-received-seqno so far
98 */
99 static inline struct tfrc_rx_hist_entry *
100 tfrc_rx_hist_last_rcv(const struct tfrc_rx_hist *h)
101 {
102 return h->ring[tfrc_rx_hist_index(h, h->loss_count)];
103 }
104
105 /**
106 * tfrc_rx_hist_entry - return the n-th history entry after loss_start
107 */
108 static inline struct tfrc_rx_hist_entry *
109 tfrc_rx_hist_entry(const struct tfrc_rx_hist *h, const u8 n)
110 {
111 return h->ring[tfrc_rx_hist_index(h, n)];
112 }
113
114 /**
115 * tfrc_rx_hist_loss_prev - entry with highest-received-seqno before loss was detected
116 */
117 static inline struct tfrc_rx_hist_entry *
118 tfrc_rx_hist_loss_prev(const struct tfrc_rx_hist *h)
119 {
120 return h->ring[h->loss_start];
121 }
122
123 /* indicate whether previously a packet was detected missing */
124 static inline bool tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h)
125 {
126 return h->loss_count > 0;
127 }
128
129 void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h, const struct sk_buff *skb,
130 const u64 ndp);
131
132 int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb);
133
134 struct tfrc_loss_hist;
135 int tfrc_rx_handle_loss(struct tfrc_rx_hist *h, struct tfrc_loss_hist *lh,
136 struct sk_buff *skb, const u64 ndp,
137 u32 (*first_li)(struct sock *sk), struct sock *sk);
138 u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h, const struct sk_buff *skb);
139 int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h);
140 void tfrc_rx_hist_purge(struct tfrc_rx_hist *h);
141
142 #endif /* _DCCP_PKT_HIST_ */
143
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