net/sctp/tsnmap.c

   1 /* SCTP kernel implementation
   2  * (C) Copyright IBM Corp. 2001, 2004
   3  * Copyright (c) 1999-2000 Cisco, Inc.
   4  * Copyright (c) 1999-2001 Motorola, Inc.
   5  * Copyright (c) 2001 Intel Corp.
   6  *
   7  * This file is part of the SCTP kernel implementation
   8  *
   9  * These functions manipulate sctp tsn mapping array.
  10  *
  11  * This SCTP implementation is free software;
  12  * you can redistribute it and/or modify it under the terms of
  13  * the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2, or (at your option)
  15  * any later version.
  16  *
  17  * This SCTP implementation is distributed in the hope that it
  18  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  19  *                 ************************
  20  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  21  * See the GNU General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU General Public License
  24  * along with GNU CC; see the file COPYING.  If not, write to
  25  * the Free Software Foundation, 59 Temple Place - Suite 330,
  26  * Boston, MA 02111-1307, USA.
  27  *
  28  * Please send any bug reports or fixes you make to the
  29  * email address(es):
  30  *    lksctp developers <lksctp-developers@lists.sourceforge.net>
  31  *
  32  * Or submit a bug report through the following website:
  33  *    http://www.sf.net/projects/lksctp
  34  *
  35  * Written or modified by:
  36  *    La Monte H.P. Yarroll <piggy@acm.org>
  37  *    Jon Grimm             <jgrimm@us.ibm.com>
  38  *    Karl Knutson          <karl@athena.chicago.il.us>
  39  *    Sridhar Samudrala     <sri@us.ibm.com>
  40  *
  41  * Any bugs reported given to us we will try to fix... any fixes shared will
  42  * be incorporated into the next SCTP release.
  43  */
  44
  45 #include <linux/types.h>
  46 #include <linux/bitmap.h>
  47 #include <net/sctp/sctp.h>
  48 #include <net/sctp/sm.h>
  49
  50 static void sctp_tsnmap_update(struct sctp_tsnmap *map);
  51 static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off,
  52                                      __u16 len, __u16 *start, __u16 *end);
  53 static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 gap);
  54
  55 /* Initialize a block of memory as a tsnmap.  */
  56 struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *map, __u16 len,
  57                                      __u32 initial_tsn, gfp_t gfp)
  58 {
  59         if (!map->tsn_map) {
  60                 map->tsn_map = kzalloc(len>>3, gfp);
  61                 if (map->tsn_map == NULL)
  62                         return NULL;
  63
  64                 map->len = len;
  65         } else {
  66                 bitmap_zero(map->tsn_map, map->len);
  67         }
  68
  69         /* Keep track of TSNs represented by tsn_map.  */
  70         map->base_tsn = initial_tsn;
  71         map->cumulative_tsn_ack_point = initial_tsn - 1;
  72         map->max_tsn_seen = map->cumulative_tsn_ack_point;
  73         map->num_dup_tsns = 0;
  74
  75         return map;
  76 }
  77
  78 void sctp_tsnmap_free(struct sctp_tsnmap *map)
  79 {
  80         map->len = 0;
  81         kfree(map->tsn_map);
  82 }
  83
  84 /* Test the tracking state of this TSN.
  85  * Returns:
  86  *   0 if the TSN has not yet been seen
  87  *  >0 if the TSN has been seen (duplicate)
  88  *  <0 if the TSN is invalid (too large to track)
  89  */
  90 int sctp_tsnmap_check(const struct sctp_tsnmap *map, __u32 tsn)
  91 {
  92         u32 gap;
  93
  94         /* Check to see if this is an old TSN */
  95         if (TSN_lte(tsn, map->cumulative_tsn_ack_point))
  96                 return 1;
  97
  98         /* Verify that we can hold this TSN and that it will not
  99          * overlfow our map
 100          */
 101         if (!TSN_lt(tsn, map->base_tsn + SCTP_TSN_MAP_SIZE))
 102                 return -1;
 103
 104         /* Calculate the index into the mapping arrays.  */
 105         gap = tsn - map->base_tsn;
 106
 107         /* Check to see if TSN has already been recorded.  */
 108         if (gap < map->len && test_bit(gap, map->tsn_map))
 109                 return 1;
 110         else
 111                 return 0;
 112 }
 113
 114
 115 /* Mark this TSN as seen.  */
 116 int sctp_tsnmap_mark(struct sctp_tsnmap *map, __u32 tsn)
 117 {
 118         u16 gap;
 119
 120         if (TSN_lt(tsn, map->base_tsn))
 121                 return 0;
 122
 123         gap = tsn - map->base_tsn;
 124
 125         if (gap >= map->len && !sctp_tsnmap_grow(map, gap))
 126                 return -ENOMEM;
 127
 128         if (!sctp_tsnmap_has_gap(map) && gap == 0) {
 129                 /* In this case the map has no gaps and the tsn we are
 130                  * recording is the next expected tsn.  We don't touch
 131                  * the map but simply bump the values.
 132                  */
 133                 map->max_tsn_seen++;
 134                 map->cumulative_tsn_ack_point++;
 135                 map->base_tsn++;
 136         } else {
 137                 /* Either we already have a gap, or about to record a gap, so
 138                  * have work to do.
 139                  *
 140                  * Bump the max.
 141                  */
 142                 if (TSN_lt(map->max_tsn_seen, tsn))
 143                         map->max_tsn_seen = tsn;
 144
 145                 /* Mark the TSN as received.  */
 146                 set_bit(gap, map->tsn_map);
 147
 148                 /* Go fixup any internal TSN mapping variables including
 149                  * cumulative_tsn_ack_point.
 150                  */
 151                 sctp_tsnmap_update(map);
 152         }
 153
 154         return 0;
 155 }
 156
 157
 158 /* Initialize a Gap Ack Block iterator from memory being provided.  */
 159 SCTP_STATIC void sctp_tsnmap_iter_init(const struct sctp_tsnmap *map,
 160                                        struct sctp_tsnmap_iter *iter)
 161 {
 162         /* Only start looking one past the Cumulative TSN Ack Point.  */
 163         iter->start = map->cumulative_tsn_ack_point + 1;
 164 }
 165
 166 /* Get the next Gap Ack Blocks. Returns 0 if there was not another block
 167  * to get.
 168  */
 169 SCTP_STATIC int sctp_tsnmap_next_gap_ack(const struct sctp_tsnmap *map,
 170                                          struct sctp_tsnmap_iter *iter,
 171                                          __u16 *start, __u16 *end)
 172 {
 173         int ended = 0;
 174         __u16 start_ = 0, end_ = 0, offset;
 175
 176         /* If there are no more gap acks possible, get out fast.  */
 177         if (TSN_lte(map->max_tsn_seen, iter->start))
 178                 return 0;
 179
 180         offset = iter->start - map->base_tsn;
 181         sctp_tsnmap_find_gap_ack(map->tsn_map, offset, map->len,
 182                                  &start_, &end_);
 183
 184         /* The Gap Ack Block happens to end at the end of the map. */
 185         if (start_ && !end_)
 186                 end_ = map->len - 1;
 187
 188         /* If we found a Gap Ack Block, return the start and end and
 189          * bump the iterator forward.
 190          */
 191         if (end_) {
 192                 /* Fix up the start and end based on the
 193                  * Cumulative TSN Ack which is always 1 behind base.
 194                  */
 195                 *start = start_ + 1;
 196                 *end = end_ + 1;
 197
 198                 /* Move the iterator forward.  */
 199                 iter->start = map->cumulative_tsn_ack_point + *end + 1;
 200                 ended = 1;
 201         }
 202
 203         return ended;
 204 }
 205
 206 /* Mark this and any lower TSN as seen.  */
 207 void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn)
 208 {
 209         u32 gap;
 210
 211         if (TSN_lt(tsn, map->base_tsn))
 212                 return;
 213         if (!TSN_lt(tsn, map->base_tsn + SCTP_TSN_MAP_SIZE))
 214                 return;
 215
 216         /* Bump the max.  */
 217         if (TSN_lt(map->max_tsn_seen, tsn))
 218                 map->max_tsn_seen = tsn;
 219
 220         gap = tsn - map->base_tsn + 1;
 221
 222         map->base_tsn += gap;
 223         map->cumulative_tsn_ack_point += gap;
 224         if (gap >= map->len) {
 225                 /* If our gap is larger then the map size, just
 226                  * zero out the map.
 227                  */
 228                 bitmap_zero(map->tsn_map, map->len);
 229         } else {
 230                 /* If the gap is smaller than the map size,
 231                  * shift the map by 'gap' bits and update further.
 232                  */
 233                 bitmap_shift_right(map->tsn_map, map->tsn_map, gap, map->len);
 234                 sctp_tsnmap_update(map);
 235         }
 236 }
 237
 238 /********************************************************************
 239  * 2nd Level Abstractions
 240  ********************************************************************/
 241
 242 /* This private helper function updates the tsnmap buffers and
 243  * the Cumulative TSN Ack Point.
 244  */
 245 static void sctp_tsnmap_update(struct sctp_tsnmap *map)
 246 {
 247         u16 len;
 248         unsigned long zero_bit;
 249
 250
 251         len = map->max_tsn_seen - map->cumulative_tsn_ack_point;
 252         zero_bit = find_first_zero_bit(map->tsn_map, len);
 253         if (!zero_bit)
 254                 return;         /* The first 0-bit is bit 0.  nothing to do */
 255
 256         map->base_tsn += zero_bit;
 257         map->cumulative_tsn_ack_point += zero_bit;
 258
 259         bitmap_shift_right(map->tsn_map, map->tsn_map, zero_bit, map->len);
 260 }
 261
 262 /* How many data chunks  are we missing from our peer?
 263  */
 264 __u16 sctp_tsnmap_pending(struct sctp_tsnmap *map)
 265 {
 266         __u32 cum_tsn = map->cumulative_tsn_ack_point;
 267         __u32 max_tsn = map->max_tsn_seen;
 268         __u32 base_tsn = map->base_tsn;
 269         __u16 pending_data;
 270         u32 gap, i;
 271
 272         pending_data = max_tsn - cum_tsn;
 273         gap = max_tsn - base_tsn;
 274
 275         if (gap == 0 || gap >= map->len)
 276                 goto out;
 277
 278         for (i = 0; i < gap+1; i++) {
 279                 if (test_bit(i, map->tsn_map))
 280                         pending_data--;
 281         }
 282
 283 out:
 284         return pending_data;
 285 }
 286
 287 /* This is a private helper for finding Gap Ack Blocks.  It searches a
 288  * single array for the start and end of a Gap Ack Block.
 289  *
 290  * The flags "started" and "ended" tell is if we found the beginning
 291  * or (respectively) the end of a Gap Ack Block.
 292  */
 293 static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off,
 294                                      __u16 len, __u16 *start, __u16 *end)
 295 {
 296         int i = off;
 297
 298         /* Look through the entire array, but break out
 299          * early if we have found the end of the Gap Ack Block.
 300          */
 301
 302         /* Also, stop looking past the maximum TSN seen. */
 303
 304         /* Look for the start. */
 305         i = find_next_bit(map, len, off);
 306         if (i < len)
 307                 *start = i;
 308
 309         /* Look for the end.  */
 310         if (*start) {
 311                 /* We have found the start, let's find the
 312                  * end.  If we find the end, break out.
 313                  */
 314                 i = find_next_zero_bit(map, len, i);
 315                 if (i < len)
 316                         *end = i - 1;
 317         }
 318 }
 319
 320 /* Renege that we have seen a TSN.  */
 321 void sctp_tsnmap_renege(struct sctp_tsnmap *map, __u32 tsn)
 322 {
 323         u32 gap;
 324
 325         if (TSN_lt(tsn, map->base_tsn))
 326                 return;
 327         /* Assert: TSN is in range.  */
 328         if (!TSN_lt(tsn, map->base_tsn + map->len))
 329                 return;
 330
 331         gap = tsn - map->base_tsn;
 332
 333         /* Pretend we never saw the TSN.  */
 334         clear_bit(gap, map->tsn_map);
 335 }
 336
 337 /* How many gap ack blocks do we have recorded? */
 338 __u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map,
 339                            struct sctp_gap_ack_block *gabs)
 340 {
 341         struct sctp_tsnmap_iter iter;
 342         int ngaps = 0;
 343
 344         /* Refresh the gap ack information. */
 345         if (sctp_tsnmap_has_gap(map)) {
 346                 __u16 start, end;
 347                 sctp_tsnmap_iter_init(map, &iter);
 348                 while (sctp_tsnmap_next_gap_ack(map, &iter,
 349                                                 &start,
 350                                                 &end)) {
 351
 352                         gabs[ngaps].start = htons(start);
 353                         gabs[ngaps].end = htons(end);
 354                         ngaps++;
 355                         if (ngaps >= SCTP_MAX_GABS)
 356                                 break;
 357                 }
 358         }
 359         return ngaps;
 360 }
 361
 362 static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 gap)
 363 {
 364         unsigned long *new;
 365         unsigned long inc;
 366         u16  len;
 367
 368         if (gap >= SCTP_TSN_MAP_SIZE)
 369                 return 0;
 370
 371         inc = ALIGN((gap - map->len),BITS_PER_LONG) + SCTP_TSN_MAP_INCREMENT;
 372         len = min_t(u16, map->len + inc, SCTP_TSN_MAP_SIZE);
 373
 374         new = kzalloc(len>>3, GFP_ATOMIC);
 375         if (!new)
 376                 return 0;
 377
 378         bitmap_copy(new, map->tsn_map, map->max_tsn_seen - map->base_tsn);
 379         kfree(map->tsn_map);
 380         map->tsn_map = new;
 381         map->len = len;
 382
 383         return 1;
 384 }