release/src-rt-6.x.4708/linux/linux-2.6.36/net/dccp/ccids/lib/packet_history.h

   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 struct tfrc_tx_hist_entry;
  44
  45 extern int  tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno);
  46 extern void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp);
  47 extern 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  */
  63 struct 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  * @ring:               Packet history for RTT sampling and loss detection
  74  * @loss_count:         Number of entries in circular history
  75  * @loss_start:         Movable index (for loss detection)
  76  * @rtt_sample_prev:    Used during RTT sampling, points to candidate entry
  77  */
  78 struct tfrc_rx_hist {
  79         struct tfrc_rx_hist_entry *ring[TFRC_NDUPACK + 1];
  80         u8                        loss_count:2,
  81                                   loss_start:2;
  82 #define rtt_sample_prev           loss_start
  83 };
  84
  85 /**
  86  * tfrc_rx_hist_index - index to reach n-th entry after loss_start
  87  */
  88 static inline u8 tfrc_rx_hist_index(const struct tfrc_rx_hist *h, const u8 n)
  89 {
  90         return (h->loss_start + n) & TFRC_NDUPACK;
  91 }
  92
  93 /**
  94  * tfrc_rx_hist_last_rcv - entry with highest-received-seqno so far
  95  */
  96 static inline struct tfrc_rx_hist_entry *
  97                         tfrc_rx_hist_last_rcv(const struct tfrc_rx_hist *h)
  98 {
  99         return h->ring[tfrc_rx_hist_index(h, h->loss_count)];
 100 }
 101
 102 /**
 103  * tfrc_rx_hist_entry - return the n-th history entry after loss_start
 104  */
 105 static inline struct tfrc_rx_hist_entry *
 106                         tfrc_rx_hist_entry(const struct tfrc_rx_hist *h, const u8 n)
 107 {
 108         return h->ring[tfrc_rx_hist_index(h, n)];
 109 }
 110
 111 /**
 112  * tfrc_rx_hist_loss_prev - entry with highest-received-seqno before loss was detected
 113  */
 114 static inline struct tfrc_rx_hist_entry *
 115                         tfrc_rx_hist_loss_prev(const struct tfrc_rx_hist *h)
 116 {
 117         return h->ring[h->loss_start];
 118 }
 119
 120 /* indicate whether previously a packet was detected missing */
 121 static inline bool tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h)
 122 {
 123         return h->loss_count > 0;
 124 }
 125
 126 extern void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h,
 127                                     const struct sk_buff *skb, const u64 ndp);
 128
 129 extern int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb);
 130
 131 struct tfrc_loss_hist;
 132 extern int  tfrc_rx_handle_loss(struct tfrc_rx_hist *h,
 133                                 struct tfrc_loss_hist *lh,
 134                                 struct sk_buff *skb, const u64 ndp,
 135                                 u32 (*first_li)(struct sock *sk),
 136                                 struct sock *sk);
 137 extern u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h,
 138                                    const struct sk_buff *skb);
 139 extern int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h);
 140 extern void tfrc_rx_hist_purge(struct tfrc_rx_hist *h);
 141
 142 #endif /* _DCCP_PKT_HIST_ */