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/slab.h>
  46 #include <linux/types.h>
  47 #include <linux/bitmap.h>
  48 #include <net/sctp/sctp.h>
  49 #include <net/sctp/sm.h>
  50
  51 static void sctp_tsnmap_update(struct sctp_tsnmap *map);
  52 static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off,
  53                                      __u16 len, __u16 *start, __u16 *end);
  54 static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 gap);
  55
  56 /* Initialize a block of memory as a tsnmap.  */
  57 struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *map, __u16 len,
  58                                      __u32 initial_tsn, gfp_t gfp)
  59 {
  60         if (!map->tsn_map) {
  61                 map->tsn_map = kzalloc(len>>3, gfp);
  62                 if (map->tsn_map == NULL)
  63                         return NULL;
  64
  65                 map->len = len;
  66         } else {
  67                 bitmap_zero(map->tsn_map, map->len);
  68         }
  69
  70         /* Keep track of TSNs represented by tsn_map.  */
  71         map->base_tsn = initial_tsn;
  72         map->cumulative_tsn_ack_point = initial_tsn - 1;
  73         map->max_tsn_seen = map->cumulative_tsn_ack_point;
  74         map->num_dup_tsns = 0;
  75
  76         return map;
  77 }
  78
  79 void sctp_tsnmap_free(struct sctp_tsnmap *map)
  80 {
  81         map->len = 0;
  82         kfree(map->tsn_map);
  83 }
  84
  85 /* Test the tracking state of this TSN.
  86  * Returns:
  87  *   0 if the TSN has not yet been seen
  88  *  >0 if the TSN has been seen (duplicate)
  89  *  <0 if the TSN is invalid (too large to track)
  90  */
  91 int sctp_tsnmap_check(const struct sctp_tsnmap *map, __u32 tsn)
  92 {
  93         u32 gap;
  94
  95         /* Check to see if this is an old TSN */
  96         if (TSN_lte(tsn, map->cumulative_tsn_ack_point))
  97                 return 1;
  98
  99         /* Verify that we can hold this TSN and that it will not
 100          * overlfow our map
 101          */
 102         if (!TSN_lt(tsn, map->base_tsn + SCTP_TSN_MAP_SIZE))
 103                 return -1;
 104
 105         /* Calculate the index into the mapping arrays.  */
 106         gap = tsn - map->base_tsn;
 107
 108         /* Check to see if TSN has already been recorded.  */
 109         if (gap < map->len && test_bit(gap, map->tsn_map))
 110                 return 1;
 111         else
 112                 return 0;
 113 }
 114
 115
 116 /* Mark this TSN as seen.  */
 117 int sctp_tsnmap_mark(struct sctp_tsnmap *map, __u32 tsn)
 118 {
 119         u16 gap;
 120
 121         if (TSN_lt(tsn, map->base_tsn))
 122                 return 0;
 123
 124         gap = tsn - map->base_tsn;
 125
 126         if (gap >= map->len && !sctp_tsnmap_grow(map, gap))
 127                 return -ENOMEM;
 128
 129         if (!sctp_tsnmap_has_gap(map) && gap == 0) {
 130                 /* In this case the map has no gaps and the tsn we are
 131                  * recording is the next expected tsn.  We don't touch
 132                  * the map but simply bump the values.
 133                  */
 134                 map->max_tsn_seen++;
 135                 map->cumulative_tsn_ack_point++;
 136                 map->base_tsn++;
 137         } else {
 138                 /* Either we already have a gap, or about to record a gap, so
 139                  * have work to do.
 140                  *
 141                  * Bump the max.
 142                  */
 143                 if (TSN_lt(map->max_tsn_seen, tsn))
 144                         map->max_tsn_seen = tsn;
 145
 146                 /* Mark the TSN as received.  */
 147                 set_bit(gap, map->tsn_map);
 148
 149                 /* Go fixup any internal TSN mapping variables including
 150                  * cumulative_tsn_ack_point.
 151                  */
 152                 sctp_tsnmap_update(map);
 153         }
 154
 155         return 0;
 156 }
 157
 158
 159 /* Initialize a Gap Ack Block iterator from memory being provided.  */
 160 SCTP_STATIC void sctp_tsnmap_iter_init(const struct sctp_tsnmap *map,
 161                                        struct sctp_tsnmap_iter *iter)
 162 {
 163         /* Only start looking one past the Cumulative TSN Ack Point.  */
 164         iter->start = map->cumulative_tsn_ack_point + 1;
 165 }
 166
 167 /* Get the next Gap Ack Blocks. Returns 0 if there was not another block
 168  * to get.
 169  */
 170 SCTP_STATIC int sctp_tsnmap_next_gap_ack(const struct sctp_tsnmap *map,
 171                                          struct sctp_tsnmap_iter *iter,
 172                                          __u16 *start, __u16 *end)
 173 {
 174         int ended = 0;
 175         __u16 start_ = 0, end_ = 0, offset;
 176
 177         /* If there are no more gap acks possible, get out fast.  */
 178         if (TSN_lte(map->max_tsn_seen, iter->start))
 179                 return 0;
 180
 181         offset = iter->start - map->base_tsn;
 182         sctp_tsnmap_find_gap_ack(map->tsn_map, offset, map->len,
 183                                  &start_, &end_);
 184
 185         /* The Gap Ack Block happens to end at the end of the map. */
 186         if (start_ && !end_)
 187                 end_ = map->len - 1;
 188
 189         /* If we found a Gap Ack Block, return the start and end and
 190          * bump the iterator forward.
 191          */
 192         if (end_) {
 193                 /* Fix up the start and end based on the
 194                  * Cumulative TSN Ack which is always 1 behind base.
 195                  */
 196                 *start = start_ + 1;
 197                 *end = end_ + 1;
 198
 199                 /* Move the iterator forward.  */
 200                 iter->start = map->cumulative_tsn_ack_point + *end + 1;
 201                 ended = 1;
 202         }
 203
 204         return ended;
 205 }
 206
 207 /* Mark this and any lower TSN as seen.  */
 208 void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn)
 209 {
 210         u32 gap;
 211
 212         if (TSN_lt(tsn, map->base_tsn))
 213                 return;
 214         if (!TSN_lt(tsn, map->base_tsn + SCTP_TSN_MAP_SIZE))
 215                 return;
 216
 217         /* Bump the max.  */
 218         if (TSN_lt(map->max_tsn_seen, tsn))
 219                 map->max_tsn_seen = tsn;
 220
 221         gap = tsn - map->base_tsn + 1;
 222
 223         map->base_tsn += gap;
 224         map->cumulative_tsn_ack_point += gap;
 225         if (gap >= map->len) {
 226                 /* If our gap is larger then the map size, just
 227                  * zero out the map.
 228                  */
 229                 bitmap_zero(map->tsn_map, map->len);
 230         } else {
 231                 /* If the gap is smaller than the map size,
 232                  * shift the map by 'gap' bits and update further.
 233                  */
 234                 bitmap_shift_right(map->tsn_map, map->tsn_map, gap, map->len);
 235                 sctp_tsnmap_update(map);
 236         }
 237 }
 238
 239 /********************************************************************
 240  * 2nd Level Abstractions
 241  ********************************************************************/
 242
 243 /* This private helper function updates the tsnmap buffers and
 244  * the Cumulative TSN Ack Point.
 245  */
 246 static void sctp_tsnmap_update(struct sctp_tsnmap *map)
 247 {
 248         u16 len;
 249         unsigned long zero_bit;
 250
 251
 252         len = map->max_tsn_seen - map->cumulative_tsn_ack_point;
 253         zero_bit = find_first_zero_bit(map->tsn_map, len);
 254         if (!zero_bit)
 255                 return;         /* The first 0-bit is bit 0.  nothing to do */
 256
 257         map->base_tsn += zero_bit;
 258         map->cumulative_tsn_ack_point += zero_bit;
 259
 260         bitmap_shift_right(map->tsn_map, map->tsn_map, zero_bit, map->len);
 261 }
 262
 263 /* How many data chunks  are we missing from our peer?
 264  */
 265 __u16 sctp_tsnmap_pending(struct sctp_tsnmap *map)
 266 {
 267         __u32 cum_tsn = map->cumulative_tsn_ack_point;
 268         __u32 max_tsn = map->max_tsn_seen;
 269         __u32 base_tsn = map->base_tsn;
 270         __u16 pending_data;
 271         u32 gap, i;
 272
 273         pending_data = max_tsn - cum_tsn;
 274         gap = max_tsn - base_tsn;
 275
 276         if (gap == 0 || gap >= map->len)
 277                 goto out;
 278
 279         for (i = 0; i < gap+1; i++) {
 280                 if (test_bit(i, map->tsn_map))
 281                         pending_data--;
 282         }
 283
 284 out:
 285         return pending_data;
 286 }
 287
 288 /* This is a private helper for finding Gap Ack Blocks.  It searches a
 289  * single array for the start and end of a Gap Ack Block.
 290  *
 291  * The flags "started" and "ended" tell is if we found the beginning
 292  * or (respectively) the end of a Gap Ack Block.
 293  */
 294 static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off,
 295                                      __u16 len, __u16 *start, __u16 *end)
 296 {
 297         int i = off;
 298
 299         /* Look through the entire array, but break out
 300          * early if we have found the end of the Gap Ack Block.
 301          */
 302
 303         /* Also, stop looking past the maximum TSN seen. */
 304
 305         /* Look for the start. */
 306         i = find_next_bit(map, len, off);
 307         if (i < len)
 308                 *start = i;
 309
 310         /* Look for the end.  */
 311         if (*start) {
 312                 /* We have found the start, let's find the
 313                  * end.  If we find the end, break out.
 314                  */
 315                 i = find_next_zero_bit(map, len, i);
 316                 if (i < len)
 317                         *end = i - 1;
 318         }
 319 }
 320
 321 /* Renege that we have seen a TSN.  */
 322 void sctp_tsnmap_renege(struct sctp_tsnmap *map, __u32 tsn)
 323 {
 324         u32 gap;
 325
 326         if (TSN_lt(tsn, map->base_tsn))
 327                 return;
 328         /* Assert: TSN is in range.  */
 329         if (!TSN_lt(tsn, map->base_tsn + map->len))
 330                 return;
 331
 332         gap = tsn - map->base_tsn;
 333
 334         /* Pretend we never saw the TSN.  */
 335         clear_bit(gap, map->tsn_map);
 336 }
 337
 338 /* How many gap ack blocks do we have recorded? */
 339 __u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map,
 340                            struct sctp_gap_ack_block *gabs)
 341 {
 342         struct sctp_tsnmap_iter iter;
 343         int ngaps = 0;
 344
 345         /* Refresh the gap ack information. */
 346         if (sctp_tsnmap_has_gap(map)) {
 347                 __u16 start, end;
 348                 sctp_tsnmap_iter_init(map, &iter);
 349                 while (sctp_tsnmap_next_gap_ack(map, &iter,
 350                                                 &start,
 351                                                 &end)) {
 352
 353                         gabs[ngaps].start = htons(start);
 354                         gabs[ngaps].end = htons(end);
 355                         ngaps++;
 356                         if (ngaps >= SCTP_MAX_GABS)
 357                                 break;
 358                 }
 359         }
 360         return ngaps;
 361 }
 362
 363 static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 gap)
 364 {
 365         unsigned long *new;
 366         unsigned long inc;
 367         u16  len;
 368
 369         if (gap >= SCTP_TSN_MAP_SIZE)
 370                 return 0;
 371
 372         inc = ALIGN((gap - map->len),BITS_PER_LONG) + SCTP_TSN_MAP_INCREMENT;
 373         len = min_t(u16, map->len + inc, SCTP_TSN_MAP_SIZE);
 374
 375         new = kzalloc(len>>3, GFP_ATOMIC);
 376         if (!new)
 377                 return 0;
 378
 379         bitmap_copy(new, map->tsn_map, map->max_tsn_seen - map->base_tsn);
 380         kfree(map->tsn_map);
 381         map->tsn_map = new;
 382         map->len = len;
 383
 384         return 1;
 385 }