net/dccp/ccids/lib/packet_history.c

   1 /*
   2  *  net/dccp/packet_history.c
   3  *
   4  *  Copyright (c) 2005 The University of Waikato, Hamilton, New Zealand.
   5  *
   6  *  An implementation of the DCCP protocol
   7  *
   8  *  This code has been developed by the University of Waikato WAND
   9  *  research group. For further information please see http://www.wand.net.nz/
  10  *  or e-mail Ian McDonald - iam4@cs.waikato.ac.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  *  This program is free software; you can redistribute it and/or modify
  23  *  it under the terms of the GNU General Public License as published by
  24  *  the Free Software Foundation; either version 2 of the License, or
  25  *  (at your option) any later version.
  26  *
  27  *  This program is distributed in the hope that it will be useful,
  28  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  29  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  30  *  GNU General Public License for more details.
  31  *
  32  *  You should have received a copy of the GNU General Public License
  33  *  along with this program; if not, write to the Free Software
  34  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  35  */
  36
  37 #include <linux/module.h>
  38 #include <linux/string.h>
  39
  40 #include "packet_history.h"
  41
  42 struct dccp_rx_hist *dccp_rx_hist_new(const char *name)
  43 {
  44         struct dccp_rx_hist *hist = kmalloc(sizeof(*hist), GFP_ATOMIC);
  45         static const char dccp_rx_hist_mask[] = "rx_hist_%s";
  46         char *slab_name;
  47
  48         if (hist == NULL)
  49                 goto out;
  50
  51         slab_name = kmalloc(strlen(name) + sizeof(dccp_rx_hist_mask) - 1,
  52                             GFP_ATOMIC);
  53         if (slab_name == NULL)
  54                 goto out_free_hist;
  55
  56         sprintf(slab_name, dccp_rx_hist_mask, name);
  57         hist->dccprxh_slab = kmem_cache_create(slab_name,
  58                                              sizeof(struct dccp_rx_hist_entry),
  59                                                0, SLAB_HWCACHE_ALIGN,
  60                                                NULL, NULL);
  61         if (hist->dccprxh_slab == NULL)
  62                 goto out_free_slab_name;
  63 out:
  64         return hist;
  65 out_free_slab_name:
  66         kfree(slab_name);
  67 out_free_hist:
  68         kfree(hist);
  69         hist = NULL;
  70         goto out;
  71 }
  72
  73 EXPORT_SYMBOL_GPL(dccp_rx_hist_new);
  74
  75 void dccp_rx_hist_delete(struct dccp_rx_hist *hist)
  76 {
  77         const char* name = kmem_cache_name(hist->dccprxh_slab);
  78
  79         kmem_cache_destroy(hist->dccprxh_slab);
  80         kfree(name);
  81         kfree(hist);
  82 }
  83
  84 EXPORT_SYMBOL_GPL(dccp_rx_hist_delete);
  85
  86 void dccp_rx_hist_purge(struct dccp_rx_hist *hist, struct list_head *list)
  87 {
  88         struct dccp_rx_hist_entry *entry, *next;
  89
  90         list_for_each_entry_safe(entry, next, list, dccphrx_node) {
  91                 list_del_init(&entry->dccphrx_node);
  92                 kmem_cache_free(hist->dccprxh_slab, entry);
  93         }
  94 }
  95
  96 EXPORT_SYMBOL_GPL(dccp_rx_hist_purge);
  97
  98 struct dccp_rx_hist_entry *
  99                 dccp_rx_hist_find_data_packet(const struct list_head *list)
 100 {
 101         struct dccp_rx_hist_entry *entry, *packet = NULL;
 102
 103         list_for_each_entry(entry, list, dccphrx_node)
 104                 if (entry->dccphrx_type == DCCP_PKT_DATA ||
 105                     entry->dccphrx_type == DCCP_PKT_DATAACK) {
 106                         packet = entry;
 107                         break;
 108                 }
 109
 110         return packet;
 111 }
 112
 113 EXPORT_SYMBOL_GPL(dccp_rx_hist_find_data_packet);
 114
 115 int dccp_rx_hist_add_packet(struct dccp_rx_hist *hist,
 116                             struct list_head *rx_list,
 117                             struct list_head *li_list,
 118                             struct dccp_rx_hist_entry *packet)
 119 {
 120         struct dccp_rx_hist_entry *entry, *next, *iter;
 121         u8 num_later = 0;
 122
 123         iter = dccp_rx_hist_head(rx_list);
 124         if (iter == NULL)
 125                 dccp_rx_hist_add_entry(rx_list, packet);
 126         else {
 127                 const u64 seqno = packet->dccphrx_seqno;
 128
 129                 if (after48(seqno, iter->dccphrx_seqno))
 130                         dccp_rx_hist_add_entry(rx_list, packet);
 131                 else {
 132                         if (dccp_rx_hist_entry_data_packet(iter))
 133                                 num_later = 1;
 134
 135                         list_for_each_entry_continue(iter, rx_list,
 136                                                      dccphrx_node) {
 137                                 if (after48(seqno, iter->dccphrx_seqno)) {
 138                                         dccp_rx_hist_add_entry(&iter->dccphrx_node,
 139                                                                packet);
 140                                         goto trim_history;
 141                                 }
 142
 143                                 if (dccp_rx_hist_entry_data_packet(iter))
 144                                         num_later++;
 145
 146                                 if (num_later == TFRC_RECV_NUM_LATE_LOSS) {
 147                                         dccp_rx_hist_entry_delete(hist, packet);
 148                                         return 1;
 149                                 }
 150                         }
 151
 152                         if (num_later < TFRC_RECV_NUM_LATE_LOSS)
 153                                 dccp_rx_hist_add_entry(rx_list, packet);
 154                         /*
 155                          * FIXME: else what? should we destroy the packet
 156                          * like above?
 157                          */
 158                 }
 159         }
 160
 161 trim_history:
 162         /*
 163          * Trim history (remove all packets after the NUM_LATE_LOSS + 1
 164          * data packets)
 165          */
 166         num_later = TFRC_RECV_NUM_LATE_LOSS + 1;
 167
 168         if (!list_empty(li_list)) {
 169                 list_for_each_entry_safe(entry, next, rx_list, dccphrx_node) {
 170                         if (num_later == 0) {
 171                                 list_del_init(&entry->dccphrx_node);
 172                                 dccp_rx_hist_entry_delete(hist, entry);
 173                         } else if (dccp_rx_hist_entry_data_packet(entry))
 174                                 --num_later;
 175                 }
 176         } else {
 177                 int step = 0;
 178                 u8 win_count = 0; /* Not needed, but lets shut up gcc */
 179                 int tmp;
 180                 /*
 181                  * We have no loss interval history so we need at least one
 182                  * rtt:s of data packets to approximate rtt.
 183                  */
 184                 list_for_each_entry_safe(entry, next, rx_list, dccphrx_node) {
 185                         if (num_later == 0) {
 186                                 switch (step) {
 187                                 case 0:
 188                                         step = 1;
 189                                         /* OK, find next data packet */
 190                                         num_later = 1;
 191                                         break;
 192                                 case 1:
 193                                         step = 2;
 194                                         /* OK, find next data packet */
 195                                         num_later = 1;
 196                                         win_count = entry->dccphrx_ccval;
 197                                         break;
 198                                 case 2:
 199                                         tmp = win_count - entry->dccphrx_ccval;
 200                                         if (tmp < 0)
 201                                                 tmp += TFRC_WIN_COUNT_LIMIT;
 202                                         if (tmp > TFRC_WIN_COUNT_PER_RTT + 1) {
 203                                                 /*
 204                                                  * We have found a packet older
 205                                                  * than one rtt remove the rest
 206                                                  */
 207                                                 step = 3;
 208                                         } else /* OK, find next data packet */
 209                                                 num_later = 1;
 210                                         break;
 211                                 case 3:
 212                                         list_del_init(&entry->dccphrx_node);
 213                                         dccp_rx_hist_entry_delete(hist, entry);
 214                                         break;
 215                                 }
 216                         } else if (dccp_rx_hist_entry_data_packet(entry))
 217                                 --num_later;
 218                 }
 219         }
 220
 221         return 0;
 222 }
 223
 224 EXPORT_SYMBOL_GPL(dccp_rx_hist_add_packet);
 225
 226 u64 dccp_rx_hist_detect_loss(struct list_head *rx_list,
 227                              struct list_head *li_list, u8 *win_loss)
 228 {
 229         struct dccp_rx_hist_entry *entry, *next, *packet;
 230         struct dccp_rx_hist_entry *a_loss = NULL;
 231         struct dccp_rx_hist_entry *b_loss = NULL;
 232         u64 seq_loss = DCCP_MAX_SEQNO + 1;
 233         u8 num_later = TFRC_RECV_NUM_LATE_LOSS;
 234
 235         list_for_each_entry_safe(entry, next, rx_list, dccphrx_node) {
 236                 if (num_later == 0) {
 237                         b_loss = entry;
 238                         break;
 239                 } else if (dccp_rx_hist_entry_data_packet(entry))
 240                         --num_later;
 241         }
 242
 243         if (b_loss == NULL)
 244                 goto out;
 245
 246         num_later = 1;
 247         list_for_each_entry_safe_continue(entry, next, rx_list, dccphrx_node) {
 248                 if (num_later == 0) {
 249                         a_loss = entry;
 250                         break;
 251                 } else if (dccp_rx_hist_entry_data_packet(entry))
 252                         --num_later;
 253         }
 254
 255         if (a_loss == NULL) {
 256                 if (list_empty(li_list)) {
 257                         /* no loss event have occured yet */
 258                         LIMIT_NETDEBUG("%s: TODO: find a lost data packet by "
 259                                        "comparing to initial seqno\n",
 260                                        __FUNCTION__);
 261                         goto out;
 262                 } else {
 263                         LIMIT_NETDEBUG("%s: Less than 4 data pkts in history!",
 264                                        __FUNCTION__);
 265                         goto out;
 266                 }
 267         }
 268
 269         /* Locate a lost data packet */
 270         entry = packet = b_loss;
 271         list_for_each_entry_safe_continue(entry, next, rx_list, dccphrx_node) {
 272                 u64 delta = dccp_delta_seqno(entry->dccphrx_seqno,
 273                                              packet->dccphrx_seqno);
 274
 275                 if (delta != 0) {
 276                         if (dccp_rx_hist_entry_data_packet(packet))
 277                                 --delta;
 278                         /*
 279                          * FIXME: check this, probably this % usage is because
 280                          * in earlier drafts the ndp count was just 8 bits
 281                          * long, but now it cam be up to 24 bits long.
 282                          */
 283 #if 0
 284                         if (delta % DCCP_NDP_LIMIT !=
 285                             (packet->dccphrx_ndp -
 286                              entry->dccphrx_ndp) % DCCP_NDP_LIMIT)
 287 #endif
 288                         if (delta != packet->dccphrx_ndp - entry->dccphrx_ndp) {
 289                                 seq_loss = entry->dccphrx_seqno;
 290                                 dccp_inc_seqno(&seq_loss);
 291                         }
 292                 }
 293                 packet = entry;
 294                 if (packet == a_loss)
 295                         break;
 296         }
 297 out:
 298         if (seq_loss != DCCP_MAX_SEQNO + 1)
 299                 *win_loss = a_loss->dccphrx_ccval;
 300         else
 301                 *win_loss = 0; /* Paranoia */
 302
 303         return seq_loss;
 304 }
 305
 306 EXPORT_SYMBOL_GPL(dccp_rx_hist_detect_loss);
 307
 308 struct dccp_tx_hist *dccp_tx_hist_new(const char *name)
 309 {
 310         struct dccp_tx_hist *hist = kmalloc(sizeof(*hist), GFP_ATOMIC);
 311         static const char dccp_tx_hist_mask[] = "tx_hist_%s";
 312         char *slab_name;
 313
 314         if (hist == NULL)
 315                 goto out;
 316
 317         slab_name = kmalloc(strlen(name) + sizeof(dccp_tx_hist_mask) - 1,
 318                             GFP_ATOMIC);
 319         if (slab_name == NULL)
 320                 goto out_free_hist;
 321
 322         sprintf(slab_name, dccp_tx_hist_mask, name);
 323         hist->dccptxh_slab = kmem_cache_create(slab_name,
 324                                              sizeof(struct dccp_tx_hist_entry),
 325                                                0, SLAB_HWCACHE_ALIGN,
 326                                                NULL, NULL);
 327         if (hist->dccptxh_slab == NULL)
 328                 goto out_free_slab_name;
 329 out:
 330         return hist;
 331 out_free_slab_name:
 332         kfree(slab_name);
 333 out_free_hist:
 334         kfree(hist);
 335         hist = NULL;
 336         goto out;
 337 }
 338
 339 EXPORT_SYMBOL_GPL(dccp_tx_hist_new);
 340
 341 void dccp_tx_hist_delete(struct dccp_tx_hist *hist)
 342 {
 343         const char* name = kmem_cache_name(hist->dccptxh_slab);
 344
 345         kmem_cache_destroy(hist->dccptxh_slab);
 346         kfree(name);
 347         kfree(hist);
 348 }
 349
 350 EXPORT_SYMBOL_GPL(dccp_tx_hist_delete);
 351
 352 struct dccp_tx_hist_entry *
 353         dccp_tx_hist_find_entry(const struct list_head *list, const u64 seq)
 354 {
 355         struct dccp_tx_hist_entry *packet = NULL, *entry;
 356
 357         list_for_each_entry(entry, list, dccphtx_node)
 358                 if (entry->dccphtx_seqno == seq) {
 359                         packet = entry;
 360                         break;
 361                 }
 362
 363         return packet;
 364 }
 365
 366 EXPORT_SYMBOL_GPL(dccp_tx_hist_find_entry);
 367
 368 void dccp_tx_hist_purge_older(struct dccp_tx_hist *hist,
 369                               struct list_head *list,
 370                               struct dccp_tx_hist_entry *packet)
 371 {
 372         struct dccp_tx_hist_entry *next;
 373
 374         list_for_each_entry_safe_continue(packet, next, list, dccphtx_node) {
 375                 list_del_init(&packet->dccphtx_node);
 376                 dccp_tx_hist_entry_delete(hist, packet);
 377         }
 378 }
 379
 380 EXPORT_SYMBOL_GPL(dccp_tx_hist_purge_older);
 381
 382 void dccp_tx_hist_purge(struct dccp_tx_hist *hist, struct list_head *list)
 383 {
 384         struct dccp_tx_hist_entry *entry, *next;
 385
 386         list_for_each_entry_safe(entry, next, list, dccphtx_node) {
 387                 list_del_init(&entry->dccphtx_node);
 388                 dccp_tx_hist_entry_delete(hist, entry);
 389         }
 390 }
 391
 392 EXPORT_SYMBOL_GPL(dccp_tx_hist_purge);
 393
 394 MODULE_AUTHOR("Ian McDonald <iam4@cs.waikato.ac.nz>, "
 395               "Arnaldo Carvalho de Melo <acme@ghostprotocols.net>");
 396 MODULE_DESCRIPTION("DCCP TFRC library");
 397 MODULE_LICENSE("GPL");