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[/] [openrisc/] [trunk/] [rtos/] [freertos-6.1.1/] [Demo/] [Common/] [ethernet/] [lwIP/] [core/] [pbuf.c] - Blame information for rev 867

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Line No. Rev Author Line
1 606 jeremybenn
/**
2
 * @file
3
 * Packet buffer management
4
 *
5
 * Packets are built from the pbuf data structure. It supports dynamic
6
 * memory allocation for packet contents or can reference externally
7
 * managed packet contents both in RAM and ROM. Quick allocation for
8
 * incoming packets is provided through pools with fixed sized pbufs.
9
 *
10
 * A packet may span over multiple pbufs, chained as a singly linked
11
 * list. This is called a "pbuf chain".
12
 *
13
 * Multiple packets may be queued, also using this singly linked list.
14
 * This is called a "packet queue".
15
 *
16
 * So, a packet queue consists of one or more pbuf chains, each of
17
 * which consist of one or more pbufs. Currently, queues are only
18
 * supported in a limited section of lwIP, this is the etharp queueing
19
 * code. Outside of this section no packet queues are supported yet.
20
 *
21
 * The differences between a pbuf chain and a packet queue are very
22
 * precise but subtle.
23
 *
24
 * The last pbuf of a packet has a ->tot_len field that equals the
25
 * ->len field. It can be found by traversing the list. If the last
26
 * pbuf of a packet has a ->next field other than NULL, more packets
27
 * are on the queue.
28
 *
29
 * Therefore, looping through a pbuf of a single packet, has an
30
 * loop end condition (tot_len == p->len), NOT (next == NULL).
31
 */
32
 
33
/*
34
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
35
 * All rights reserved.
36
 *
37
 * Redistribution and use in source and binary forms, with or without modification,
38
 * are permitted provided that the following conditions are met:
39
 *
40
 * 1. Redistributions of source code must retain the above copyright notice,
41
 *    this list of conditions and the following disclaimer.
42
 * 2. Redistributions in binary form must reproduce the above copyright notice,
43
 *    this list of conditions and the following disclaimer in the documentation
44
 *    and/or other materials provided with the distribution.
45
 * 3. The name of the author may not be used to endorse or promote products
46
 *    derived from this software without specific prior written permission.
47
 *
48
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
49
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
50
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
51
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
52
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
53
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
54
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
55
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
56
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
57
 * OF SUCH DAMAGE.
58
 *
59
 * This file is part of the lwIP TCP/IP stack.
60
 *
61
 * Author: Adam Dunkels <adam@sics.se>
62
 *
63
 */
64
 
65
#include <string.h>
66
 
67
#include "lwip/opt.h"
68
#include "lwip/stats.h"
69
#include "lwip/def.h"
70
#include "lwip/mem.h"
71
#include "lwip/memp.h"
72
#include "lwip/pbuf.h"
73
#include "lwip/sys.h"
74
#include "arch/perf.h"
75
 
76
static u8_t pbuf_pool_memory[MEM_ALIGNMENT - 1 + PBUF_POOL_SIZE * MEM_ALIGN_SIZE(PBUF_POOL_BUFSIZE + sizeof(struct pbuf))];
77
 
78
#if !SYS_LIGHTWEIGHT_PROT
79
static volatile u8_t pbuf_pool_free_lock, pbuf_pool_alloc_lock;
80
static sys_sem_t pbuf_pool_free_sem;
81
#endif
82
 
83
static struct pbuf *pbuf_pool = NULL;
84
 
85
/**
86
 * Initializes the pbuf module.
87
 *
88
 * A large part of memory is allocated for holding the pool of pbufs.
89
 * The size of the individual pbufs in the pool is given by the size
90
 * parameter, and the number of pbufs in the pool by the num parameter.
91
 *
92
 * After the memory has been allocated, the pbufs are set up. The
93
 * ->next pointer in each pbuf is set up to point to the next pbuf in
94
 * the pool.
95
 *
96
 */
97
void
98
pbuf_init(void)
99
{
100
  struct pbuf *p, *q = NULL;
101
  u16_t i;
102
 
103
  pbuf_pool = (struct pbuf *)MEM_ALIGN(pbuf_pool_memory);
104
 
105
#if PBUF_STATS
106
  lwip_stats.pbuf.avail = PBUF_POOL_SIZE;
107
#endif /* PBUF_STATS */
108
 
109
  /* Set up ->next pointers to link the pbufs of the pool together */
110
  p = pbuf_pool;
111
 
112
  for(i = 0; i < PBUF_POOL_SIZE; ++i) {
113
    p->next = (struct pbuf *)((u8_t *)p + PBUF_POOL_BUFSIZE + sizeof(struct pbuf));
114
    p->len = p->tot_len = PBUF_POOL_BUFSIZE;
115
    p->payload = MEM_ALIGN((void *)((u8_t *)p + sizeof(struct pbuf)));
116
    p->flags = PBUF_FLAG_POOL;
117
    q = p;
118
    p = p->next;
119
  }
120
 
121
  /* The ->next pointer of last pbuf is NULL to indicate that there
122
     are no more pbufs in the pool */
123
  q->next = NULL;
124
 
125
#if !SYS_LIGHTWEIGHT_PROT
126
  pbuf_pool_alloc_lock = 0;
127
  pbuf_pool_free_lock = 0;
128
  pbuf_pool_free_sem = sys_sem_new(1);
129
#endif
130
}
131
 
132
/**
133
 * @internal only called from pbuf_alloc()
134
 */
135
static struct pbuf *
136
pbuf_pool_alloc(void)
137
{
138
  struct pbuf *p = NULL;
139
 
140
  SYS_ARCH_DECL_PROTECT(old_level);
141
  SYS_ARCH_PROTECT(old_level);
142
 
143
#if !SYS_LIGHTWEIGHT_PROT
144
  /* Next, check the actual pbuf pool, but if the pool is locked, we
145
     pretend to be out of buffers and return NULL. */
146
  if (pbuf_pool_free_lock) {
147
#if PBUF_STATS
148
    ++lwip_stats.pbuf.alloc_locked;
149
#endif /* PBUF_STATS */
150
    return NULL;
151
  }
152
  pbuf_pool_alloc_lock = 1;
153
  if (!pbuf_pool_free_lock) {
154
#endif /* SYS_LIGHTWEIGHT_PROT */
155
    p = pbuf_pool;
156
    if (p) {
157
      pbuf_pool = p->next;
158
    }
159
#if !SYS_LIGHTWEIGHT_PROT
160
#if PBUF_STATS
161
  } else {
162
    ++lwip_stats.pbuf.alloc_locked;
163
#endif /* PBUF_STATS */
164
  }
165
  pbuf_pool_alloc_lock = 0;
166
#endif /* SYS_LIGHTWEIGHT_PROT */
167
 
168
#if PBUF_STATS
169
  if (p != NULL) {
170
    ++lwip_stats.pbuf.used;
171
    if (lwip_stats.pbuf.used > lwip_stats.pbuf.max) {
172
      lwip_stats.pbuf.max = lwip_stats.pbuf.used;
173
    }
174
  }
175
#endif /* PBUF_STATS */
176
 
177
  SYS_ARCH_UNPROTECT(old_level);
178
  return p;
179
}
180
 
181
 
182
/**
183
 * Allocates a pbuf of the given type (possibly a chain for PBUF_POOL type).
184
 *
185
 * The actual memory allocated for the pbuf is determined by the
186
 * layer at which the pbuf is allocated and the requested size
187
 * (from the size parameter).
188
 *
189
 * @param flag this parameter decides how and where the pbuf
190
 * should be allocated as follows:
191
 *
192
 * - PBUF_RAM: buffer memory for pbuf is allocated as one large
193
 *             chunk. This includes protocol headers as well.
194
 * - PBUF_ROM: no buffer memory is allocated for the pbuf, even for
195
 *             protocol headers. Additional headers must be prepended
196
 *             by allocating another pbuf and chain in to the front of
197
 *             the ROM pbuf. It is assumed that the memory used is really
198
 *             similar to ROM in that it is immutable and will not be
199
 *             changed. Memory which is dynamic should generally not
200
 *             be attached to PBUF_ROM pbufs. Use PBUF_REF instead.
201
 * - PBUF_REF: no buffer memory is allocated for the pbuf, even for
202
 *             protocol headers. It is assumed that the pbuf is only
203
 *             being used in a single thread. If the pbuf gets queued,
204
 *             then pbuf_take should be called to copy the buffer.
205
 * - PBUF_POOL: the pbuf is allocated as a pbuf chain, with pbufs from
206
 *              the pbuf pool that is allocated during pbuf_init().
207
 *
208
 * @return the allocated pbuf. If multiple pbufs where allocated, this
209
 * is the first pbuf of a pbuf chain.
210
 */
211
struct pbuf *
212
pbuf_alloc(pbuf_layer l, u16_t length, pbuf_flag flag)
213
{
214
  struct pbuf *p, *q, *r;
215
  u16_t offset;
216
  s32_t rem_len; /* remaining length */
217
  LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 3, ("pbuf_alloc(length=%"U16_F")\n", length));
218
 
219
  /* determine header offset */
220
  offset = 0;
221
  switch (l) {
222
  case PBUF_TRANSPORT:
223
    /* add room for transport (often TCP) layer header */
224
    offset += PBUF_TRANSPORT_HLEN;
225
    /* FALLTHROUGH */
226
  case PBUF_IP:
227
    /* add room for IP layer header */
228
    offset += PBUF_IP_HLEN;
229
    /* FALLTHROUGH */
230
  case PBUF_LINK:
231
    /* add room for link layer header */
232
    offset += PBUF_LINK_HLEN;
233
    break;
234
  case PBUF_RAW:
235
    break;
236
  default:
237
    LWIP_ASSERT("pbuf_alloc: bad pbuf layer", 0);
238
    return NULL;
239
  }
240
 
241
  switch (flag) {
242
  case PBUF_POOL:
243
    /* allocate head of pbuf chain into p */
244
    p = pbuf_pool_alloc();
245
    LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 3, ("pbuf_alloc: allocated pbuf %p\n", (void *)p));
246
    if (p == NULL) {
247
#if PBUF_STATS
248
      ++lwip_stats.pbuf.err;
249
#endif /* PBUF_STATS */
250
      return NULL;
251
    }
252
    p->next = NULL;
253
 
254
    /* make the payload pointer point 'offset' bytes into pbuf data memory */
255
    p->payload = MEM_ALIGN((void *)((u8_t *)p + (sizeof(struct pbuf) + offset)));
256
    LWIP_ASSERT("pbuf_alloc: pbuf p->payload properly aligned",
257
            ((mem_ptr_t)p->payload % MEM_ALIGNMENT) == 0);
258
    /* the total length of the pbuf chain is the requested size */
259
    p->tot_len = length;
260
    /* set the length of the first pbuf in the chain */
261
    p->len = length > PBUF_POOL_BUFSIZE - offset? PBUF_POOL_BUFSIZE - offset: length;
262
    /* set reference count (needed here in case we fail) */
263
    p->ref = 1;
264
 
265
    /* now allocate the tail of the pbuf chain */
266
 
267
    /* remember first pbuf for linkage in next iteration */
268
    r = p;
269
    /* remaining length to be allocated */
270
    rem_len = length - p->len;
271
    /* any remaining pbufs to be allocated? */
272
    while (rem_len > 0) {
273
      q = pbuf_pool_alloc();
274
      if (q == NULL) {
275
       LWIP_DEBUGF(PBUF_DEBUG | 2, ("pbuf_alloc: Out of pbufs in pool.\n"));
276
#if PBUF_STATS
277
        ++lwip_stats.pbuf.err;
278
#endif /* PBUF_STATS */
279
        /* free chain so far allocated */
280
        pbuf_free(p);
281
        /* bail out unsuccesfully */
282
        return NULL;
283
      }
284
      q->next = NULL;
285
      /* make previous pbuf point to this pbuf */
286
      r->next = q;
287
      /* set total length of this pbuf and next in chain */
288
      q->tot_len = rem_len;
289
      /* this pbuf length is pool size, unless smaller sized tail */
290
      q->len = rem_len > PBUF_POOL_BUFSIZE? PBUF_POOL_BUFSIZE: rem_len;
291
      q->payload = (void *)((u8_t *)q + sizeof(struct pbuf));
292
      LWIP_ASSERT("pbuf_alloc: pbuf q->payload properly aligned",
293
              ((mem_ptr_t)q->payload % MEM_ALIGNMENT) == 0);
294
      q->ref = 1;
295
      /* calculate remaining length to be allocated */
296
      rem_len -= q->len;
297
      /* remember this pbuf for linkage in next iteration */
298
      r = q;
299
    }
300
    /* end of chain */
301
    /*r->next = NULL;*/
302
 
303
    break;
304
  case PBUF_RAM:
305
    /* If pbuf is to be allocated in RAM, allocate memory for it. */
306
    p = mem_malloc(MEM_ALIGN_SIZE(sizeof(struct pbuf) + offset) + MEM_ALIGN_SIZE(length));
307
    if (p == NULL) {
308
      return NULL;
309
    }
310
    /* Set up internal structure of the pbuf. */
311
    p->payload = MEM_ALIGN((void *)((u8_t *)p + sizeof(struct pbuf) + offset));
312
    p->len = p->tot_len = length;
313
    p->next = NULL;
314
    p->flags = PBUF_FLAG_RAM;
315
 
316
    LWIP_ASSERT("pbuf_alloc: pbuf->payload properly aligned",
317
           ((mem_ptr_t)p->payload % MEM_ALIGNMENT) == 0);
318
    break;
319
  /* pbuf references existing (non-volatile static constant) ROM payload? */
320
  case PBUF_ROM:
321
  /* pbuf references existing (externally allocated) RAM payload? */
322
  case PBUF_REF:
323
    /* only allocate memory for the pbuf structure */
324
    p = memp_malloc(MEMP_PBUF);
325
    if (p == NULL) {
326
      LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_alloc: Could not allocate MEMP_PBUF for PBUF_%s.\n", flag == PBUF_ROM?"ROM":"REF"));
327
 
328
      return NULL;
329
    }
330
    /* caller must set this field properly, afterwards */
331
    p->payload = NULL;
332
    p->len = p->tot_len = length;
333
    p->next = NULL;
334
    p->flags = (flag == PBUF_ROM? PBUF_FLAG_ROM: PBUF_FLAG_REF);
335
    break;
336
  default:
337
    LWIP_ASSERT("pbuf_alloc: erroneous flag", 0);
338
    return NULL;
339
  }
340
  /* set reference count */
341
  p->ref = 1;
342
  LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 3, ("pbuf_alloc(length=%"U16_F") == %p\n", length, (void *)p));
343
  return p;
344
}
345
 
346
 
347
#if PBUF_STATS
348
#define DEC_PBUF_STATS do { --lwip_stats.pbuf.used; } while (0)
349
#else /* PBUF_STATS */
350
#define DEC_PBUF_STATS
351
#endif /* PBUF_STATS */
352
 
353
#define PBUF_POOL_FAST_FREE(p)  do {                                    \
354
                                  p->next = pbuf_pool;                  \
355
                                  pbuf_pool = p;                        \
356
                                  DEC_PBUF_STATS;                       \
357
                                } while (0)
358
 
359
#if SYS_LIGHTWEIGHT_PROT
360
#define PBUF_POOL_FREE(p)  do {                                         \
361
                                SYS_ARCH_DECL_PROTECT(old_level);       \
362
                                SYS_ARCH_PROTECT(old_level);            \
363
                                PBUF_POOL_FAST_FREE(p);                 \
364
                                SYS_ARCH_UNPROTECT(old_level);          \
365
                               } while (0)
366
#else /* SYS_LIGHTWEIGHT_PROT */
367
#define PBUF_POOL_FREE(p)  do {                                         \
368
                             sys_sem_wait(pbuf_pool_free_sem);          \
369
                             PBUF_POOL_FAST_FREE(p);                    \
370
                             sys_sem_signal(pbuf_pool_free_sem);        \
371
                           } while (0)
372
#endif /* SYS_LIGHTWEIGHT_PROT */
373
 
374
/**
375
 * Shrink a pbuf chain to a desired length.
376
 *
377
 * @param p pbuf to shrink.
378
 * @param new_len desired new length of pbuf chain
379
 *
380
 * Depending on the desired length, the first few pbufs in a chain might
381
 * be skipped and left unchanged. The new last pbuf in the chain will be
382
 * resized, and any remaining pbufs will be freed.
383
 *
384
 * @note If the pbuf is ROM/REF, only the ->tot_len and ->len fields are adjusted.
385
 * @note May not be called on a packet queue.
386
 *
387
 * @bug Cannot grow the size of a pbuf (chain) (yet).
388
 */
389
void
390
pbuf_realloc(struct pbuf *p, u16_t new_len)
391
{
392
  struct pbuf *q;
393
  u16_t rem_len; /* remaining length */
394
  s16_t grow;
395
 
396
  LWIP_ASSERT("pbuf_realloc: sane p->flags", p->flags == PBUF_FLAG_POOL ||
397
              p->flags == PBUF_FLAG_ROM ||
398
              p->flags == PBUF_FLAG_RAM ||
399
              p->flags == PBUF_FLAG_REF);
400
 
401
  /* desired length larger than current length? */
402
  if (new_len >= p->tot_len) {
403
    /* enlarging not yet supported */
404
    return;
405
  }
406
 
407
  /* the pbuf chain grows by (new_len - p->tot_len) bytes
408
   * (which may be negative in case of shrinking) */
409
  grow = new_len - p->tot_len;
410
 
411
  /* first, step over any pbufs that should remain in the chain */
412
  rem_len = new_len;
413
  q = p;
414
  /* should this pbuf be kept? */
415
  while (rem_len > q->len) {
416
    /* decrease remaining length by pbuf length */
417
    rem_len -= q->len;
418
    /* decrease total length indicator */
419
    q->tot_len += grow;
420
    /* proceed to next pbuf in chain */
421
    q = q->next;
422
  }
423
  /* we have now reached the new last pbuf (in q) */
424
  /* rem_len == desired length for pbuf q */
425
 
426
  /* shrink allocated memory for PBUF_RAM */
427
  /* (other types merely adjust their length fields */
428
  if ((q->flags == PBUF_FLAG_RAM) && (rem_len != q->len)) {
429
    /* reallocate and adjust the length of the pbuf that will be split */
430
    mem_realloc(q, (u8_t *)q->payload - (u8_t *)q + rem_len);
431
  }
432
  /* adjust length fields for new last pbuf */
433
  q->len = rem_len;
434
  q->tot_len = q->len;
435
 
436
  /* any remaining pbufs in chain? */
437
  if (q->next != NULL) {
438
    /* free remaining pbufs in chain */
439
    pbuf_free(q->next);
440
  }
441
  /* q is last packet in chain */
442
  q->next = NULL;
443
 
444
}
445
 
446
/**
447
 * Adjusts the payload pointer to hide or reveal headers in the payload.
448
 *
449
 * Adjusts the ->payload pointer so that space for a header
450
 * (dis)appears in the pbuf payload.
451
 *
452
 * The ->payload, ->tot_len and ->len fields are adjusted.
453
 *
454
 * @param hdr_size_inc Number of bytes to increment header size which
455
 * increases the size of the pbuf. New space is on the front.
456
 * (Using a negative value decreases the header size.)
457
 * If hdr_size_inc is 0, this function does nothing and returns succesful.
458
 *
459
 * PBUF_ROM and PBUF_REF type buffers cannot have their sizes increased, so
460
 * the call will fail. A check is made that the increase in header size does
461
 * not move the payload pointer in front of the start of the buffer.
462
 * @return non-zero on failure, zero on success.
463
 *
464
 */
465
u8_t
466
pbuf_header(struct pbuf *p, s16_t header_size_increment)
467
{
468
  u16_t flags;
469
  void *payload;
470
 
471
  LWIP_ASSERT("p != NULL", p != NULL);
472
  if ((header_size_increment == 0) || (p == NULL)) return 0;
473
 
474
  flags = p->flags;
475
  /* remember current payload pointer */
476
  payload = p->payload;
477
 
478
  /* pbuf types containing payloads? */
479
  if (flags == PBUF_FLAG_RAM || flags == PBUF_FLAG_POOL) {
480
    /* set new payload pointer */
481
    p->payload = (u8_t *)p->payload - header_size_increment;
482
    /* boundary check fails? */
483
    if ((u8_t *)p->payload < (u8_t *)p + sizeof(struct pbuf)) {
484
      LWIP_DEBUGF( PBUF_DEBUG | 2, ("pbuf_header: failed as %p < %p (not enough space for new header size)\n",
485
        (void *)p->payload,
486
        (void *)(p + 1)));\
487
      /* restore old payload pointer */
488
      p->payload = payload;
489
      /* bail out unsuccesfully */
490
      return 1;
491
    }
492
  /* pbuf types refering to external payloads? */
493
  } else if (flags == PBUF_FLAG_REF || flags == PBUF_FLAG_ROM) {
494
    /* hide a header in the payload? */
495
    if ((header_size_increment < 0) && (header_size_increment - p->len <= 0)) {
496
      /* increase payload pointer */
497
      p->payload = (u8_t *)p->payload - header_size_increment;
498
    } else {
499
      /* cannot expand payload to front (yet!)
500
       * bail out unsuccesfully */
501
      return 1;
502
    }
503
  }
504
  /* modify pbuf length fields */
505
  p->len += header_size_increment;
506
  p->tot_len += header_size_increment;
507
 
508
  LWIP_DEBUGF( PBUF_DEBUG, ("pbuf_header: old %p new %p (%"S16_F")\n",
509
    (void *)payload, (void *)p->payload, header_size_increment));
510
 
511
  return 0;
512
}
513
 
514
/**
515
 * Dereference a pbuf chain or queue and deallocate any no-longer-used
516
 * pbufs at the head of this chain or queue.
517
 *
518
 * Decrements the pbuf reference count. If it reaches zero, the pbuf is
519
 * deallocated.
520
 *
521
 * For a pbuf chain, this is repeated for each pbuf in the chain,
522
 * up to the first pbuf which has a non-zero reference count after
523
 * decrementing. So, when all reference counts are one, the whole
524
 * chain is free'd.
525
 *
526
 * @param pbuf The pbuf (chain) to be dereferenced.
527
 *
528
 * @return the number of pbufs that were de-allocated
529
 * from the head of the chain.
530
 *
531
 * @note MUST NOT be called on a packet queue (Not verified to work yet).
532
 * @note the reference counter of a pbuf equals the number of pointers
533
 * that refer to the pbuf (or into the pbuf).
534
 *
535
 * @internal examples:
536
 *
537
 * Assuming existing chains a->b->c with the following reference
538
 * counts, calling pbuf_free(a) results in:
539
 *
540
 * 1->2->3 becomes ...1->3
541
 * 3->3->3 becomes 2->3->3
542
 * 1->1->2 becomes ......1
543
 * 2->1->1 becomes 1->1->1
544
 * 1->1->1 becomes .......
545
 *
546
 */
547
u8_t
548
pbuf_free(struct pbuf *p)
549
{
550
  u16_t flags;
551
  struct pbuf *q;
552
  u8_t count;
553
  SYS_ARCH_DECL_PROTECT(old_level);
554
 
555
  LWIP_ASSERT("p != NULL", p != NULL);
556
 
557
  /* if assertions are disabled, proceed with debug output */
558
  if (p == NULL) {
559
    LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_free(p == NULL) was called.\n"));
560
    return 0;
561
  }
562
  LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 3, ("pbuf_free(%p)\n", (void *)p));
563
 
564
  PERF_START;
565
 
566
  LWIP_ASSERT("pbuf_free: sane flags",
567
    p->flags == PBUF_FLAG_RAM || p->flags == PBUF_FLAG_ROM ||
568
    p->flags == PBUF_FLAG_REF || p->flags == PBUF_FLAG_POOL);
569
 
570
  count = 0;
571
  /* Since decrementing ref cannot be guaranteed to be a single machine operation
572
   * we must protect it. Also, the later test of ref must be protected.
573
   */
574
  SYS_ARCH_PROTECT(old_level);
575
  /* de-allocate all consecutive pbufs from the head of the chain that
576
   * obtain a zero reference count after decrementing*/
577
  while (p != NULL) {
578
    /* all pbufs in a chain are referenced at least once */
579
    LWIP_ASSERT("pbuf_free: p->ref > 0", p->ref > 0);
580
    /* decrease reference count (number of pointers to pbuf) */
581
    p->ref--;
582
    /* this pbuf is no longer referenced to? */
583
    if (p->ref == 0) {
584
      /* remember next pbuf in chain for next iteration */
585
      q = p->next;
586
      LWIP_DEBUGF( PBUF_DEBUG | 2, ("pbuf_free: deallocating %p\n", (void *)p));
587
      flags = p->flags;
588
      /* is this a pbuf from the pool? */
589
      if (flags == PBUF_FLAG_POOL) {
590
        p->len = p->tot_len = PBUF_POOL_BUFSIZE;
591
        p->payload = (void *)((u8_t *)p + sizeof(struct pbuf));
592
        PBUF_POOL_FREE(p);
593
      /* is this a ROM or RAM referencing pbuf? */
594
      } else if (flags == PBUF_FLAG_ROM || flags == PBUF_FLAG_REF) {
595
        memp_free(MEMP_PBUF, p);
596
      /* flags == PBUF_FLAG_RAM */
597
      } else {
598
        mem_free(p);
599
      }
600
      count++;
601
      /* proceed to next pbuf */
602
      p = q;
603
    /* p->ref > 0, this pbuf is still referenced to */
604
    /* (and so the remaining pbufs in chain as well) */
605
    } else {
606
      LWIP_DEBUGF( PBUF_DEBUG | 2, ("pbuf_free: %p has ref %"U16_F", ending here.\n", (void *)p, (u16_t)p->ref));
607
      /* stop walking through the chain */
608
      p = NULL;
609
    }
610
  }
611
  SYS_ARCH_UNPROTECT(old_level);
612
  PERF_STOP("pbuf_free");
613
  /* return number of de-allocated pbufs */
614
 
615
  return count;
616
}
617
 
618
/**
619
 * Count number of pbufs in a chain
620
 *
621
 * @param p first pbuf of chain
622
 * @return the number of pbufs in a chain
623
 */
624
 
625
u8_t
626
pbuf_clen(struct pbuf *p)
627
{
628
  u8_t len;
629
 
630
  len = 0;
631
  while (p != NULL) {
632
    ++len;
633
    p = p->next;
634
  }
635
  return len;
636
}
637
 
638
/**
639
 * Increment the reference count of the pbuf.
640
 *
641
 * @param p pbuf to increase reference counter of
642
 *
643
 */
644
void
645
pbuf_ref(struct pbuf *p)
646
{
647
  SYS_ARCH_DECL_PROTECT(old_level);
648
  /* pbuf given? */
649
  if (p != NULL) {
650
    SYS_ARCH_PROTECT(old_level);
651
    ++(p->ref);
652
    SYS_ARCH_UNPROTECT(old_level);
653
  }
654
}
655
 
656
/**
657
 * Concatenate two pbufs (each may be a pbuf chain) and take over
658
 * the caller's reference of the tail pbuf.
659
 *
660
 * @note The caller MAY NOT reference the tail pbuf afterwards.
661
 * Use pbuf_chain() for that purpose.
662
 *
663
 * @see pbuf_chain()
664
 */
665
 
666
void
667
pbuf_cat(struct pbuf *h, struct pbuf *t)
668
{
669
  struct pbuf *p;
670
 
671
  LWIP_ASSERT("h != NULL (programmer violates API)", h != NULL);
672
  LWIP_ASSERT("t != NULL (programmer violates API)", t != NULL);
673
  if ((h == NULL) || (t == NULL)) return;
674
 
675
  /* proceed to last pbuf of chain */
676
  for (p = h; p->next != NULL; p = p->next) {
677
    /* add total length of second chain to all totals of first chain */
678
    p->tot_len += t->tot_len;
679
  }
680
  /* { p is last pbuf of first h chain, p->next == NULL } */
681
  LWIP_ASSERT("p->tot_len == p->len (of last pbuf in chain)", p->tot_len == p->len);
682
  LWIP_ASSERT("p->next == NULL", p->next == NULL);
683
  /* add total length of second chain to last pbuf total of first chain */
684
  p->tot_len += t->tot_len;
685
  /* chain last pbuf of head (p) with first of tail (t) */
686
  p->next = t;
687
  /* p->next now references t, but the caller will drop its reference to t,
688
   * so netto there is no change to the reference count of t.
689
   */
690
}
691
 
692
/**
693
 * Chain two pbufs (or pbuf chains) together.
694
 *
695
 * The caller MUST call pbuf_free(t) once it has stopped
696
 * using it. Use pbuf_cat() instead if you no longer use t.
697
 *
698
 * @param h head pbuf (chain)
699
 * @param t tail pbuf (chain)
700
 * @note The pbufs MUST belong to the same packet.
701
 * @note MAY NOT be called on a packet queue.
702
 *
703
 * The ->tot_len fields of all pbufs of the head chain are adjusted.
704
 * The ->next field of the last pbuf of the head chain is adjusted.
705
 * The ->ref field of the first pbuf of the tail chain is adjusted.
706
 *
707
 */
708
void
709
pbuf_chain(struct pbuf *h, struct pbuf *t)
710
{
711
  pbuf_cat(h, t);
712
  /* t is now referenced by h */
713
  pbuf_ref(t);
714
  LWIP_DEBUGF(PBUF_DEBUG | DBG_FRESH | 2, ("pbuf_chain: %p references %p\n", (void *)h, (void *)t));
715
}
716
 
717
/* For packet queueing. Note that queued packets MUST be dequeued first
718
 * using pbuf_dequeue() before calling other pbuf_() functions. */
719
#if ARP_QUEUEING
720
/**
721
 * Add a packet to the end of a queue.
722
 *
723
 * @param q pointer to first packet on the queue
724
 * @param n packet to be queued
725
 *
726
 * Both packets MUST be given, and must be different.
727
 */
728
void
729
pbuf_queue(struct pbuf *p, struct pbuf *n)
730
{
731
#if PBUF_DEBUG /* remember head of queue */
732
  struct pbuf *q = p;
733
#endif
734
  /* programmer stupidity checks */
735
  LWIP_ASSERT("p == NULL in pbuf_queue: this indicates a programmer error\n", p != NULL);
736
  LWIP_ASSERT("n == NULL in pbuf_queue: this indicates a programmer error\n", n != NULL);
737
  LWIP_ASSERT("p == n in pbuf_queue: this indicates a programmer error\n", p != n);
738
  if ((p == NULL) || (n == NULL) || (p == n)){
739
    LWIP_DEBUGF(PBUF_DEBUG | DBG_HALT | 3, ("pbuf_queue: programmer argument error\n"));
740
    return;
741
  }
742
 
743
  /* iterate through all packets on queue */
744
  while (p->next != NULL) {
745
/* be very picky about pbuf chain correctness */
746
#if PBUF_DEBUG
747
    /* iterate through all pbufs in packet */
748
    while (p->tot_len != p->len) {
749
      /* make sure invariant condition holds */
750
      LWIP_ASSERT("p->len < p->tot_len", p->len < p->tot_len);
751
      /* make sure each packet is complete */
752
      LWIP_ASSERT("p->next != NULL", p->next != NULL);
753
      p = p->next;
754
      /* { p->tot_len == p->len => p is last pbuf of a packet } */
755
    }
756
    /* { p is last pbuf of a packet } */
757
    /* proceed to next packet on queue */
758
#endif
759
    /* proceed to next pbuf */
760
    if (p->next != NULL) p = p->next;
761
  }
762
  /* { p->tot_len == p->len and p->next == NULL } ==>
763
   * { p is last pbuf of last packet on queue } */
764
  /* chain last pbuf of queue with n */
765
  p->next = n;
766
  /* n is now referenced to by the (packet p in the) queue */
767
  pbuf_ref(n);
768
#if PBUF_DEBUG
769
  LWIP_DEBUGF(PBUF_DEBUG | DBG_FRESH | 2,
770
    ("pbuf_queue: newly queued packet %p sits after packet %p in queue %p\n",
771
    (void *)n, (void *)p, (void *)q));
772
#endif
773
}
774
 
775
/**
776
 * Remove a packet from the head of a queue.
777
 *
778
 * The caller MUST reference the remainder of the queue (as returned). The
779
 * caller MUST NOT call pbuf_ref() as it implicitly takes over the reference
780
 * from p.
781
 *
782
 * @param p pointer to first packet on the queue which will be dequeued.
783
 * @return first packet on the remaining queue (NULL if no further packets).
784
 *
785
 */
786
struct pbuf *
787
pbuf_dequeue(struct pbuf *p)
788
{
789
  struct pbuf *q;
790
  LWIP_ASSERT("p != NULL", p != NULL);
791
 
792
  /* iterate through all pbufs in packet p */
793
  while (p->tot_len != p->len) {
794
    /* make sure invariant condition holds */
795
    LWIP_ASSERT("p->len < p->tot_len", p->len < p->tot_len);
796
    /* make sure each packet is complete */
797
    LWIP_ASSERT("p->next != NULL", p->next != NULL);
798
    p = p->next;
799
  }
800
  /* { p->tot_len == p->len } => p is the last pbuf of the first packet */
801
  /* remember next packet on queue in q */
802
  q = p->next;
803
  /* dequeue packet p from queue */
804
  p->next = NULL;
805
  /* any next packet on queue? */
806
  if (q != NULL) {
807
    /* although q is no longer referenced by p, it MUST be referenced by
808
     * the caller, who is maintaining this packet queue. So, we do not call
809
     * pbuf_free(q) here, resulting in an implicit pbuf_ref(q) for the caller. */
810
    LWIP_DEBUGF(PBUF_DEBUG | DBG_FRESH | 2, ("pbuf_dequeue: first remaining packet on queue is %p\n", (void *)q));
811
  } else {
812
    LWIP_DEBUGF(PBUF_DEBUG | DBG_FRESH | 2, ("pbuf_dequeue: no further packets on queue\n"));
813
  }
814
  return q;
815
}
816
#endif
817
 
818
/**
819
 *
820
 * Create PBUF_POOL (or PBUF_RAM) copies of PBUF_REF pbufs.
821
 *
822
 * Used to queue packets on behalf of the lwIP stack, such as
823
 * ARP based queueing.
824
 *
825
 * Go through a pbuf chain and replace any PBUF_REF buffers
826
 * with PBUF_POOL (or PBUF_RAM) pbufs, each taking a copy of
827
 * the referenced data.
828
 *
829
 * @note You MUST explicitly use p = pbuf_take(p);
830
 * The pbuf you give as argument, may have been replaced
831
 * by a (differently located) copy through pbuf_take()!
832
 *
833
 * @note Any replaced pbufs will be freed through pbuf_free().
834
 * This may deallocate them if they become no longer referenced.
835
 *
836
 * @param p Head of pbuf chain to process
837
 *
838
 * @return Pointer to head of pbuf chain
839
 */
840
struct pbuf *
841
pbuf_take(struct pbuf *p)
842
{
843
  struct pbuf *q , *prev, *head;
844
  LWIP_ASSERT("pbuf_take: p != NULL\n", p != NULL);
845
  LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 3, ("pbuf_take(%p)\n", (void*)p));
846
 
847
  prev = NULL;
848
  head = p;
849
  /* iterate through pbuf chain */
850
  do
851
  {
852
    /* pbuf is of type PBUF_REF? */
853
    if (p->flags == PBUF_FLAG_REF) {
854
      LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE, ("pbuf_take: encountered PBUF_REF %p\n", (void *)p));
855
      /* allocate a pbuf (w/ payload) fully in RAM */
856
      /* PBUF_POOL buffers are faster if we can use them */
857
      if (p->len <= PBUF_POOL_BUFSIZE) {
858
        q = pbuf_alloc(PBUF_RAW, p->len, PBUF_POOL);
859
        if (q == NULL) {
860
          LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_take: Could not allocate PBUF_POOL\n"));
861
        }
862
      } else {
863
        /* no replacement pbuf yet */
864
        q = NULL;
865
        LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_take: PBUF_POOL too small to replace PBUF_REF\n"));
866
      }
867
      /* no (large enough) PBUF_POOL was available? retry with PBUF_RAM */
868
      if (q == NULL) {
869
        q = pbuf_alloc(PBUF_RAW, p->len, PBUF_RAM);
870
        if (q == NULL) {
871
          LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_take: Could not allocate PBUF_RAM\n"));
872
        }
873
      }
874
      /* replacement pbuf could be allocated? */
875
      if (q != NULL)
876
      {
877
        /* copy p to q */
878
        /* copy successor */
879
        q->next = p->next;
880
        /* remove linkage from original pbuf */
881
        p->next = NULL;
882
        /* remove linkage to original pbuf */
883
        if (prev != NULL) {
884
          /* prev->next == p at this point */
885
          LWIP_ASSERT("prev->next == p", prev->next == p);
886
          /* break chain and insert new pbuf instead */
887
          prev->next = q;
888
        /* prev == NULL, so we replaced the head pbuf of the chain */
889
        } else {
890
          head = q;
891
        }
892
        /* copy pbuf payload */
893
        memcpy(q->payload, p->payload, p->len);
894
        q->tot_len = p->tot_len;
895
        q->len = p->len;
896
        /* in case p was the first pbuf, it is no longer refered to by
897
         * our caller, as the caller MUST do p = pbuf_take(p);
898
         * in case p was not the first pbuf, it is no longer refered to
899
         * by prev. we can safely free the pbuf here.
900
         * (note that we have set p->next to NULL already so that
901
         * we will not free the rest of the chain by accident.)
902
         */
903
        pbuf_free(p);
904
        /* do not copy ref, since someone else might be using the old buffer */
905
        LWIP_DEBUGF(PBUF_DEBUG, ("pbuf_take: replaced PBUF_REF %p with %p\n", (void *)p, (void *)q));
906
        p = q;
907
      } else {
908
        /* deallocate chain */
909
        pbuf_free(head);
910
        LWIP_DEBUGF(PBUF_DEBUG | 2, ("pbuf_take: failed to allocate replacement pbuf for %p\n", (void *)p));
911
        return NULL;
912
      }
913
    /* p->flags != PBUF_FLAG_REF */
914
    } else {
915
      LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 1, ("pbuf_take: skipping pbuf not of type PBUF_REF\n"));
916
    }
917
    /* remember this pbuf */
918
    prev = p;
919
    /* proceed to next pbuf in original chain */
920
    p = p->next;
921
  } while (p);
922
  LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 1, ("pbuf_take: end of chain reached.\n"));
923
 
924
  return head;
925
}
926
 
927
/**
928
 * Dechains the first pbuf from its succeeding pbufs in the chain.
929
 *
930
 * Makes p->tot_len field equal to p->len.
931
 * @param p pbuf to dechain
932
 * @return remainder of the pbuf chain, or NULL if it was de-allocated.
933
 * @note May not be called on a packet queue.
934
 */
935
struct pbuf *
936
pbuf_dechain(struct pbuf *p)
937
{
938
  struct pbuf *q;
939
  u8_t tail_gone = 1;
940
  /* tail */
941
  q = p->next;
942
  /* pbuf has successor in chain? */
943
  if (q != NULL) {
944
    /* assert tot_len invariant: (p->tot_len == p->len + (p->next? p->next->tot_len: 0) */
945
    LWIP_ASSERT("p->tot_len == p->len + q->tot_len", q->tot_len == p->tot_len - p->len);
946
    /* enforce invariant if assertion is disabled */
947
    q->tot_len = p->tot_len - p->len;
948
    /* decouple pbuf from remainder */
949
    p->next = NULL;
950
    /* total length of pbuf p is its own length only */
951
    p->tot_len = p->len;
952
    /* q is no longer referenced by p, free it */
953
    LWIP_DEBUGF(PBUF_DEBUG | DBG_STATE, ("pbuf_dechain: unreferencing %p\n", (void *)q));
954
    tail_gone = pbuf_free(q);
955
    if (tail_gone > 0) {
956
      LWIP_DEBUGF(PBUF_DEBUG | DBG_STATE,
957
                  ("pbuf_dechain: deallocated %p (as it is no longer referenced)\n", (void *)q));
958
    }
959
    /* return remaining tail or NULL if deallocated */
960
  }
961
  /* assert tot_len invariant: (p->tot_len == p->len + (p->next? p->next->tot_len: 0) */
962
  LWIP_ASSERT("p->tot_len == p->len", p->tot_len == p->len);
963
  return (tail_gone > 0? NULL: q);
964
}

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