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 43 /** 44 * tfrc_tx_hist_entry - Simple singly-linked TX history list 45 * @next: next oldest entry (LIFO order) 46 * @seqno: sequence number of this entry 47 * @stamp: send time of packet with sequence number @seqno 48 */ 49 struct tfrc_tx_hist_entry { 50 struct tfrc_tx_hist_entry *next; 51 u64 seqno; 52 ktime_t stamp; 53 }; 54 55 static inline struct tfrc_tx_hist_entry * 56 tfrc_tx_hist_find_entry(struct tfrc_tx_hist_entry *head, u64 seqno) 57 { 58 while (head != NULL && head->seqno != seqno) 59 head = head->next; 60 return head; 61 } 62 63 int tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno); 64 void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp); 65 66 /* Subtraction a-b modulo-16, respects circular wrap-around */ 67 #define SUB16(a, b) (((a) + 16 - (b)) & 0xF) 68 69 /* Number of packets to wait after a missing packet (RFC 4342, 6.1) */ 70 #define TFRC_NDUPACK 3 71 72 /** 73 * tfrc_rx_hist_entry - Store information about a single received packet 74 * @tfrchrx_seqno: DCCP packet sequence number 75 * @tfrchrx_ccval: window counter value of packet (RFC 4342, 8.1) 76 * @tfrchrx_ndp: the NDP count (if any) of the packet 77 * @tfrchrx_tstamp: actual receive time of packet 78 */ 79 struct tfrc_rx_hist_entry { 80 u64 tfrchrx_seqno:48, 81 tfrchrx_ccval:4, 82 tfrchrx_type:4; 83 u64 tfrchrx_ndp:48; 84 ktime_t tfrchrx_tstamp; 85 }; 86 87 /** 88 * tfrc_rx_hist - RX history structure for TFRC-based protocols 89 * @ring: Packet history for RTT sampling and loss detection 90 * @loss_count: Number of entries in circular history 91 * @loss_start: Movable index (for loss detection) 92 * @rtt_sample_prev: Used during RTT sampling, points to candidate entry 93 */ 94 struct tfrc_rx_hist { 95 struct tfrc_rx_hist_entry *ring[TFRC_NDUPACK + 1]; 96 u8 loss_count:2, 97 loss_start:2; 98 #define rtt_sample_prev loss_start 99 }; 100 101 /** 102 * tfrc_rx_hist_index - index to reach n-th entry after loss_start 103 */ 104 static inline u8 tfrc_rx_hist_index(const struct tfrc_rx_hist *h, const u8 n) 105 { 106 return (h->loss_start + n) & TFRC_NDUPACK; 107 } 108 109 /** 110 * tfrc_rx_hist_last_rcv - entry with highest-received-seqno so far 111 */ 112 static inline struct tfrc_rx_hist_entry * 113 tfrc_rx_hist_last_rcv(const struct tfrc_rx_hist *h) 114 { 115 return h->ring[tfrc_rx_hist_index(h, h->loss_count)]; 116 } 117 118 /** 119 * tfrc_rx_hist_entry - return the n-th history entry after loss_start 120 */ 121 static inline struct tfrc_rx_hist_entry * 122 tfrc_rx_hist_entry(const struct tfrc_rx_hist *h, const u8 n) 123 { 124 return h->ring[tfrc_rx_hist_index(h, n)]; 125 } 126 127 /** 128 * tfrc_rx_hist_loss_prev - entry with highest-received-seqno before loss was detected 129 */ 130 static inline struct tfrc_rx_hist_entry * 131 tfrc_rx_hist_loss_prev(const struct tfrc_rx_hist *h) 132 { 133 return h->ring[h->loss_start]; 134 } 135 136 /* indicate whether previously a packet was detected missing */ 137 static inline bool tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h) 138 { 139 return h->loss_count > 0; 140 } 141 142 void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h, const struct sk_buff *skb, 143 const u64 ndp); 144 145 int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb); 146 147 struct tfrc_loss_hist; 148 int tfrc_rx_handle_loss(struct tfrc_rx_hist *h, struct tfrc_loss_hist *lh, 149 struct sk_buff *skb, const u64 ndp, 150 u32 (*first_li)(struct sock *sk), struct sock *sk); 151 u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h, const struct sk_buff *skb); 152 int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h); 153 void tfrc_rx_hist_purge(struct tfrc_rx_hist *h); 154 155 #endif /* _DCCP_PKT_HIST_ */ 156