buffer.c

Go to the documentation of this file.

/*
 * Copyright (c) 2015 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * buffer.c: allocate/free network buffers.
 *
 * Copyright (c) 2008 Eliot Dresselhaus
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include <vlib/vlib.h>

uword vlib_buffer_length_in_chain_slow_path (vlib_main_t * vm, vlib_buffer_t * b_first)
{
  vlib_buffer_t * b = b_first;
  uword l_first = b_first->current_length;
  uword l = 0;
  while (b->flags & VLIB_BUFFER_NEXT_PRESENT)
    {
      b = vlib_get_buffer (vm, b->next_buffer);
      l += b->current_length;
    }
  b_first->total_length_not_including_first_buffer = l;
  b_first->flags |= VLIB_BUFFER_TOTAL_LENGTH_VALID;
  return l + l_first;
}

u8 * format_vlib_buffer (u8 * s, va_list * args)
{
  vlib_buffer_t * b = va_arg (*args, vlib_buffer_t *);
  
  s = format (s, "current data %d, length %d, free-list %d",
              b->current_data, b->current_length,
              b->free_list_index);

  if (b->flags & VLIB_BUFFER_IS_TRACED)
    s = format (s, ", trace 0x%x", b->trace_index);

  if (b->flags & VLIB_BUFFER_NEXT_PRESENT)
    s = format (s, ", next-buffer 0x%x", b->next_buffer);

  return s;
}

u8 * format_vlib_buffer_and_data (u8 * s, va_list * args)
{
  vlib_buffer_t * b = va_arg (*args, vlib_buffer_t *);
  
  s = format (s, "%U, %U",
              format_vlib_buffer, b,
              format_hex_bytes, vlib_buffer_get_current (b), 64);

  return s;
}

static u8 * format_vlib_buffer_known_state (u8 * s, va_list * args)
{
  vlib_buffer_known_state_t state = va_arg (*args, vlib_buffer_known_state_t);
  char * t;

  switch (state)
    {
    case VLIB_BUFFER_UNKNOWN:
      t = "unknown";
      break;

    case VLIB_BUFFER_KNOWN_ALLOCATED:
      t = "known-allocated";
      break;

    case VLIB_BUFFER_KNOWN_FREE:
      t = "known-free";
      break;

    default:
      t = "invalid";
      break;
    }

  return format (s, "%s", t);
}

u8 * format_vlib_buffer_contents (u8 * s, va_list * va)
{
  vlib_main_t * vm = va_arg (*va, vlib_main_t *);
  vlib_buffer_t * b = va_arg (*va, vlib_buffer_t *);
  
  while (1)
    {
      vec_add (s, vlib_buffer_get_current (b),
               b->current_length);
      if (! (b->flags & VLIB_BUFFER_NEXT_PRESENT))
        break;
      b = vlib_get_buffer (vm, b->next_buffer);
    }

  return s;
}

static u8 *
vlib_validate_buffer_helper (vlib_main_t * vm,
                             u32 bi,
                             uword follow_buffer_next,
                             uword ** unique_hash)
                      
{
  vlib_buffer_t * b = vlib_get_buffer (vm, bi);
  vlib_buffer_main_t * bm = vm->buffer_main;
  vlib_buffer_free_list_t * fl;

  if (pool_is_free_index (bm->buffer_free_list_pool,
                          b->free_list_index))
    return format (0, "unknown free list 0x%x", b->free_list_index);

  fl = pool_elt_at_index (bm->buffer_free_list_pool,
                          b->free_list_index);

  if ((signed) b->current_data < (signed) - VLIB_BUFFER_PRE_DATA_SIZE)
    return format (0, "current data %d before pre-data", b->current_data);
#if DPDK == 0
  if (b->current_data + b->current_length > fl->n_data_bytes)
    return format (0, "%d-%d beyond end of buffer %d",
                   b->current_data, b->current_length,
                   fl->n_data_bytes);
#endif

  if (follow_buffer_next
      && (b->flags & VLIB_BUFFER_NEXT_PRESENT))
    {
      vlib_buffer_known_state_t k;
      u8 * msg, * result;

      k = vlib_buffer_is_known (vm, b->next_buffer);
      if (k != VLIB_BUFFER_KNOWN_ALLOCATED)
        return format (0, "next 0x%x: %U",
                       b->next_buffer,
                       format_vlib_buffer_known_state, k);

      if (unique_hash)
        {
          if (hash_get (*unique_hash, b->next_buffer))
            return format (0, "duplicate buffer 0x%x", b->next_buffer);

          hash_set1 (*unique_hash, b->next_buffer);
        }

      msg = vlib_validate_buffer (vm, b->next_buffer, follow_buffer_next);
      if (msg)
        {
          result = format (0, "next 0x%x: %v", b->next_buffer, msg);
          vec_free (msg);
          return result;
        }
    }

  return 0;
}

u8 *
vlib_validate_buffer (vlib_main_t * vm, u32 bi, uword follow_buffer_next)
{ return vlib_validate_buffer_helper (vm, bi, follow_buffer_next, /* unique_hash */ 0); }

u8 *
vlib_validate_buffers (vlib_main_t * vm,
                       u32 * buffers,
                       uword next_buffer_stride,
                       uword n_buffers,
                       vlib_buffer_known_state_t known_state,
                       uword follow_buffer_next)
{
  uword i, * hash;
  u32 bi, * b = buffers;
  vlib_buffer_known_state_t k;
  u8 * msg = 0, * result = 0;

  hash = hash_create (0, 0);
  for (i = 0; i < n_buffers; i++)
    {
      bi = b[0];
      b += next_buffer_stride;

      /* Buffer is not unique. */
      if (hash_get (hash, bi))
        {
          msg = format (0, "not unique");
          goto done;
        }

      k = vlib_buffer_is_known (vm, bi);
      if (k != known_state)
        {
          msg = format (0, "is %U; expected %U",
                        format_vlib_buffer_known_state, k,
                        format_vlib_buffer_known_state, known_state);
          goto done;
        }

      msg = vlib_validate_buffer_helper (vm, bi, follow_buffer_next, &hash);
      if (msg)
        goto done;

      hash_set1 (hash, bi);
    }

 done:
  if (msg)
    {
      result = format (0, "0x%x: %v", bi, msg);
      vec_free (msg);
    }
  hash_free (hash);
  return result;
}

vlib_main_t **vlib_mains;

/* When dubugging validate that given buffers are either known allocated
   or known free. */
static void
vlib_buffer_validate_alloc_free (vlib_main_t * vm,
                                 u32 * buffers,
                                 uword n_buffers,
                                 vlib_buffer_known_state_t expected_state)
{
  u32 * b;
  uword i, bi, is_free;

  if (CLIB_DEBUG == 0)
    return;

  ASSERT(os_get_cpu_number() == 0);

  /* smp disaster check */
  if (vlib_mains)
      ASSERT(vm == vlib_mains[0]);

  is_free = expected_state == VLIB_BUFFER_KNOWN_ALLOCATED;
  b = buffers;
  for (i = 0; i < n_buffers; i++)
    {
      vlib_buffer_known_state_t known;
        
      bi = b[0];
      b += 1;
      known = vlib_buffer_is_known (vm, bi);
      if (known != expected_state)
        {
          ASSERT (0);
          vlib_panic_with_msg
            (vm, "%s %U buffer 0x%x",
             is_free ? "freeing" : "allocating",
             format_vlib_buffer_known_state, known,
             bi);
        }

      vlib_buffer_set_known_state
        (vm, bi,
         is_free ? VLIB_BUFFER_KNOWN_FREE : VLIB_BUFFER_KNOWN_ALLOCATED);
    }
}

/* Aligned copy routine. */
void
vlib_aligned_memcpy (void * _dst, void * _src, int n_bytes)
{
  vlib_copy_unit_t * dst = _dst;
  vlib_copy_unit_t * src = _src;

  /* Arguments must be naturally aligned. */
  ASSERT (pointer_to_uword (dst) % sizeof (dst[0]) == 0);
  ASSERT (pointer_to_uword (src) % sizeof (src[0]) == 0);
  ASSERT (n_bytes % sizeof (dst[0]) == 0);

  if (4 * sizeof (dst[0]) == CLIB_CACHE_LINE_BYTES)
    {
      CLIB_PREFETCH (dst + 0, 4 * sizeof (dst[0]), WRITE);
      CLIB_PREFETCH (src + 0, 4 * sizeof (src[0]), READ);

      while (n_bytes >= 4 * sizeof (dst[0]))
        {
          dst += 4;
          src += 4;
          n_bytes -= 4 * sizeof (dst[0]);
          CLIB_PREFETCH (dst, 4 * sizeof (dst[0]), WRITE);
          CLIB_PREFETCH (src, 4 * sizeof (src[0]), READ);
          dst[-4] = src[-4];
          dst[-3] = src[-3];
          dst[-2] = src[-2];
          dst[-1] = src[-1];
        }
    }
  else if (8 * sizeof (dst[0]) == CLIB_CACHE_LINE_BYTES)
    {
      CLIB_PREFETCH (dst + 0, 8 * sizeof (dst[0]), WRITE);
      CLIB_PREFETCH (src + 0, 8 * sizeof (src[0]), READ);

      while (n_bytes >= 8 * sizeof (dst[0]))
        {
          dst += 8;
          src += 8;
          n_bytes -= 8 * sizeof (dst[0]);
          CLIB_PREFETCH (dst, 8 * sizeof (dst[0]), WRITE);
          CLIB_PREFETCH (src, 8 * sizeof (src[0]), READ);
          dst[-8] = src[-8];
          dst[-7] = src[-7];
          dst[-6] = src[-6];
          dst[-5] = src[-5];
          dst[-4] = src[-4];
          dst[-3] = src[-3];
          dst[-2] = src[-2];
          dst[-1] = src[-1];
        }
    }
  else
    /* Cache line size unknown: fall back to slow version. */;

  while (n_bytes > 0)
    {
      *dst++ = *src++;
      n_bytes -= 1 * sizeof (dst[0]);
    }
}

#define BUFFERS_PER_COPY (sizeof (vlib_copy_unit_t) / sizeof (u32))

/* Make sure we have at least given number of unaligned buffers. */
static void
fill_unaligned (vlib_main_t * vm,
                vlib_buffer_free_list_t * free_list,
                uword n_unaligned_buffers)
{
  word la = vec_len (free_list->aligned_buffers);
  word lu = vec_len (free_list->unaligned_buffers);

  /* Aligned come in aligned copy-sized chunks. */
  ASSERT (la % BUFFERS_PER_COPY == 0);

  ASSERT (la >= n_unaligned_buffers);

  while (lu < n_unaligned_buffers)
    {
      /* Copy 4 buffers from end of aligned vector to unaligned vector. */
      vec_add (free_list->unaligned_buffers,
               free_list->aligned_buffers + la - BUFFERS_PER_COPY,
               BUFFERS_PER_COPY);
      la -= BUFFERS_PER_COPY;
      lu += BUFFERS_PER_COPY;
    }
  _vec_len (free_list->aligned_buffers) = la;
}

/* After free aligned buffers may not contain even sized chunks. */
static void
trim_aligned (vlib_buffer_free_list_t * f)
{
  uword l, n_trim;

  /* Add unaligned to aligned before trim. */
  l = vec_len (f->unaligned_buffers);
  if (l > 0)
    {
      vec_add_aligned (f->aligned_buffers, f->unaligned_buffers, l,
                       /* align */ sizeof (vlib_copy_unit_t));

      _vec_len (f->unaligned_buffers) = 0;
    }

  /* Remove unaligned buffers from end of aligned vector and save for next trim. */
  l = vec_len (f->aligned_buffers);
  n_trim = l % BUFFERS_PER_COPY;
  if (n_trim)
    {
      /* Trim aligned -> unaligned. */
      vec_add (f->unaligned_buffers, f->aligned_buffers + l - n_trim, n_trim);

      /* Remove from aligned. */
      _vec_len (f->aligned_buffers) = l - n_trim;
    }
}

static void
merge_free_lists (vlib_buffer_free_list_t * dst,
                  vlib_buffer_free_list_t * src)
{
  uword l;
  u32 * d;
  
  trim_aligned (src);
  trim_aligned (dst);

  l = vec_len (src->aligned_buffers);
  if (l > 0)
    {
      vec_add2_aligned (dst->aligned_buffers, d, l,
                        /* align */ sizeof (vlib_copy_unit_t));
      vlib_aligned_memcpy (d, src->aligned_buffers, l * sizeof (d[0]));
      vec_free (src->aligned_buffers);
    }

  l = vec_len (src->unaligned_buffers);
  if (l > 0)
    {
      vec_add (dst->unaligned_buffers, src->unaligned_buffers, l);
      vec_free (src->unaligned_buffers);
    }
}

always_inline u32
vlib_buffer_get_free_list_with_size (vlib_main_t * vm, u32 size)
{
  vlib_buffer_main_t * bm = vm->buffer_main;

  size = vlib_buffer_round_size (size);
  uword * p = hash_get (bm->free_list_by_size, size);
  return p ? p[0] : ~0;
}

/* Add buffer free list. */
static u32
vlib_buffer_create_free_list_helper (vlib_main_t * vm,
                                     u32 n_data_bytes,
                                     u32 is_public,
                                     u32 is_default,
                                     u8 * name)
{
  vlib_buffer_main_t * bm = vm->buffer_main;
  vlib_buffer_free_list_t * f;

  if (! is_default && pool_elts (bm->buffer_free_list_pool) == 0)
    {
      u32 default_free_free_list_index;

      default_free_free_list_index =
        vlib_buffer_create_free_list_helper (vm,
                                             /* default buffer size */ VLIB_BUFFER_DEFAULT_FREE_LIST_BYTES,
                                             /* is_public */ 1,
                                             /* is_default */ 1,
                                             (u8 *) "default");
      ASSERT (default_free_free_list_index == VLIB_BUFFER_DEFAULT_FREE_LIST_INDEX);

      if (n_data_bytes == VLIB_BUFFER_DEFAULT_FREE_LIST_BYTES && is_public)
        return default_free_free_list_index;
    }

  pool_get_aligned (bm->buffer_free_list_pool, f, CLIB_CACHE_LINE_BYTES);

  memset (f, 0, sizeof (f[0]));
  f->index = f - bm->buffer_free_list_pool;
  f->n_data_bytes = vlib_buffer_round_size (n_data_bytes);
  f->min_n_buffers_each_physmem_alloc = 256;
  f->name = clib_mem_is_heap_object (name) ? name : format (0, "%s", name);

  /* Setup free buffer template. */
  f->buffer_init_template.free_list_index = f->index;

  if (is_public)
    {
      uword * p = hash_get (bm->free_list_by_size, f->n_data_bytes);
      if (! p)
        hash_set (bm->free_list_by_size, f->n_data_bytes, f->index);
    }

  return f->index;
}

u32 vlib_buffer_create_free_list (vlib_main_t * vm, u32 n_data_bytes,
                                  char * fmt, ...)
{
  va_list va;
  u8 * name;

  va_start (va, fmt);
  name = va_format (0, fmt, &va);
  va_end (va);

  return vlib_buffer_create_free_list_helper (vm, n_data_bytes,
                                              /* is_public */ 0,
                                              /* is_default */ 0,
                                              name);
}

u32 vlib_buffer_get_or_create_free_list (vlib_main_t * vm, u32 n_data_bytes,
                                         char * fmt, ...)
{
  u32 i = vlib_buffer_get_free_list_with_size (vm, n_data_bytes);

  if (i == ~0)
    {
      va_list va;
      u8 * name;

      va_start (va, fmt);
      name = va_format (0, fmt, &va);
      va_end (va);

      i = vlib_buffer_create_free_list_helper (vm, n_data_bytes,
                                               /* is_public */ 1,
                                               /* is_default */ 0,
                                               name);
    }
  
  return i;
}

static void
del_free_list (vlib_main_t * vm, vlib_buffer_free_list_t * f)
{
  u32 i;

  for (i = 0; i < vec_len (f->buffer_memory_allocated); i++)
    vm->os_physmem_free (f->buffer_memory_allocated[i]);
  vec_free (f->name);
  vec_free (f->buffer_memory_allocated);
  vec_free (f->unaligned_buffers);
  vec_free (f->aligned_buffers);
}

/* Add buffer free list. */
void vlib_buffer_delete_free_list (vlib_main_t * vm, u32 free_list_index)
{
  vlib_buffer_main_t * bm = vm->buffer_main;
  vlib_buffer_free_list_t * f;
  u32 merge_index;

  f = vlib_buffer_get_free_list (vm, free_list_index);

  ASSERT (vec_len (f->unaligned_buffers) + vec_len (f->aligned_buffers) == f->n_alloc);
  merge_index = vlib_buffer_get_free_list_with_size (vm, f->n_data_bytes);
  if (merge_index != ~0 && merge_index != free_list_index)
    {
      merge_free_lists (pool_elt_at_index (bm->buffer_free_list_pool,
                                           merge_index), f);
    }

  del_free_list (vm, f);

  /* Poison it. */
  memset (f, 0xab, sizeof (f[0]));

  pool_put (bm->buffer_free_list_pool, f);
}

/* Make sure free list has at least given number of free buffers. */
static uword
fill_free_list (vlib_main_t * vm,
                vlib_buffer_free_list_t * fl,
                uword min_free_buffers)
{
  vlib_buffer_t * buffers, * b;
  int n, n_bytes, i;
  u32 * bi;
  u32 n_remaining, n_alloc, n_this_chunk;

  trim_aligned (fl);

  /* Already have enough free buffers on free list? */
  n = min_free_buffers - vec_len (fl->aligned_buffers);
  if (n <= 0)
    return min_free_buffers;

  /* Always allocate round number of buffers. */
  n = round_pow2 (n, BUFFERS_PER_COPY);

  /* Always allocate new buffers in reasonably large sized chunks. */
  n = clib_max (n, fl->min_n_buffers_each_physmem_alloc);

  n_remaining = n;
  n_alloc = 0;
  while (n_remaining > 0)
    {
      n_this_chunk = clib_min (n_remaining, 16);
      
      n_bytes = n_this_chunk * (sizeof (b[0]) + fl->n_data_bytes);

      /* drb: removed power-of-2 ASSERT */
      buffers = vm->os_physmem_alloc_aligned (&vm->physmem_main,
                                              n_bytes, sizeof (vlib_buffer_t));
      if (! buffers)
        return n_alloc;

      /* Record chunk as being allocated so we can free it later. */
      vec_add1 (fl->buffer_memory_allocated, buffers);

      fl->n_alloc += n_this_chunk;
      n_alloc += n_this_chunk;
      n_remaining -= n_this_chunk;

      b = buffers;
      vec_add2_aligned (fl->aligned_buffers, bi, n_this_chunk, 
                        sizeof (vlib_copy_unit_t));
      for (i = 0; i < n_this_chunk; i++)
        {
          bi[i] = vlib_get_buffer_index (vm, b);

          if (CLIB_DEBUG > 0)
            vlib_buffer_set_known_state (vm, bi[i], VLIB_BUFFER_KNOWN_FREE);
          b = vlib_buffer_next_contiguous (b, fl->n_data_bytes);
        }

      memset (buffers, 0, n_bytes);

      /* Initialize all new buffers. */
      b = buffers;
      for (i = 0; i < n_this_chunk; i++)
        {
          vlib_buffer_init_for_free_list (b, fl);
          b = vlib_buffer_next_contiguous (b, fl->n_data_bytes);
        }
      
      if (fl->buffer_init_function)
        fl->buffer_init_function (vm, fl, bi, n_this_chunk);
    }
  return n_alloc;
}

always_inline uword
copy_alignment (u32 * x)
{ return (pointer_to_uword (x) / sizeof (x[0])) % BUFFERS_PER_COPY; }

static u32
alloc_from_free_list (vlib_main_t * vm,
                      vlib_buffer_free_list_t * free_list,
                      u32 * alloc_buffers,
                      u32 n_alloc_buffers)
{
  u32 * dst, * u_src;
  uword u_len, n_left;
  uword n_unaligned_start, n_unaligned_end, n_filled;

  ASSERT(os_get_cpu_number() == 0);

  n_left = n_alloc_buffers;
  dst = alloc_buffers;
  n_unaligned_start = ((BUFFERS_PER_COPY - copy_alignment (dst))
                       & (BUFFERS_PER_COPY - 1));

  n_filled = fill_free_list (vm, free_list, n_alloc_buffers);
  if (n_filled == 0)
    return 0;
  
  n_left = n_filled < n_left ? n_filled : n_left;
  n_alloc_buffers = n_left;

  if (n_unaligned_start >= n_left)
    {
      n_unaligned_start = n_left;
      n_unaligned_end = 0;
    }
  else
    n_unaligned_end = copy_alignment (dst + n_alloc_buffers);

  fill_unaligned (vm, free_list, n_unaligned_start + n_unaligned_end);

  u_len = vec_len (free_list->unaligned_buffers);
  u_src = free_list->unaligned_buffers + u_len - 1;

  if (n_unaligned_start)
    {
      uword n_copy = n_unaligned_start;
      if (n_copy > n_left)
        n_copy = n_left;
      n_left -= n_copy;

      while (n_copy > 0)
        {
          *dst++ = *u_src--;
          n_copy--;
          u_len--;
        }

      /* Now dst should be aligned. */
      if (n_left > 0)
        ASSERT (pointer_to_uword (dst) % sizeof (vlib_copy_unit_t) == 0);
    }

  /* Aligned copy. */
  {
    vlib_copy_unit_t * d, * s;
    uword n_copy;

    if (vec_len(free_list->aligned_buffers) < ((n_left/BUFFERS_PER_COPY)*BUFFERS_PER_COPY))
        abort();

    n_copy = n_left / BUFFERS_PER_COPY;
    n_left = n_left % BUFFERS_PER_COPY;

    /* Remove buffers from aligned free list. */
    _vec_len (free_list->aligned_buffers) -= n_copy * BUFFERS_PER_COPY;

    s = (vlib_copy_unit_t *) vec_end (free_list->aligned_buffers);
    d = (vlib_copy_unit_t *) dst;

    /* Fast path loop. */
    while (n_copy >= 4)
      {
        d[0] = s[0];
        d[1] = s[1];
        d[2] = s[2];
        d[3] = s[3];
        n_copy -= 4;
        s += 4;
        d += 4;
      }

    while (n_copy >= 1)
      {
        d[0] = s[0];
        n_copy -= 1;
        s += 1;
        d += 1;
      }

    dst = (void *) d;
  }

  /* Unaligned copy. */
  ASSERT (n_unaligned_end == n_left);
  while (n_left > 0)
    {
      *dst++ = *u_src--;
      n_left--;
      u_len--;
    }

  if (! free_list->unaligned_buffers)
    ASSERT (u_len == 0);
  else
    _vec_len (free_list->unaligned_buffers) = u_len;

  /* Verify that buffers are known free. */
  vlib_buffer_validate_alloc_free (vm, alloc_buffers,
                                   n_alloc_buffers,
                                   VLIB_BUFFER_KNOWN_FREE);

  return n_alloc_buffers;
}

/* Allocate a given number of buffers into given array.
   Returns number actually allocated which will be either zero or
   number requested. */
u32 vlib_buffer_alloc (vlib_main_t * vm, u32 * buffers, u32 n_buffers)
{
  vlib_buffer_main_t * bm = vm->buffer_main;
  ASSERT(os_get_cpu_number() == 0);

  return alloc_from_free_list
    (vm,
     pool_elt_at_index (bm->buffer_free_list_pool,
                        VLIB_BUFFER_DEFAULT_FREE_LIST_INDEX),
     buffers, n_buffers);
}

u32 vlib_buffer_alloc_from_free_list (vlib_main_t * vm,
                                      u32 * buffers,
                                      u32 n_buffers,
                                      u32 free_list_index)
{
  vlib_buffer_main_t * bm = vm->buffer_main;
  vlib_buffer_free_list_t * f;
  f = pool_elt_at_index (bm->buffer_free_list_pool, free_list_index);
  return alloc_from_free_list (vm, f, buffers, n_buffers);
}

always_inline void
add_buffer_to_free_list (vlib_main_t * vm,
                         vlib_buffer_free_list_t * f,
                         u32 buffer_index, u8 do_init)
{
  vlib_buffer_t * b;
  b = vlib_get_buffer (vm, buffer_index);
  if (PREDICT_TRUE(do_init))
      vlib_buffer_init_for_free_list (b, f);
  vec_add1_aligned (f->aligned_buffers, buffer_index, sizeof (vlib_copy_unit_t));
}

always_inline vlib_buffer_free_list_t *
buffer_get_free_list (vlib_main_t * vm, vlib_buffer_t * b, u32 * index)
{
  vlib_buffer_main_t * bm = vm->buffer_main;
  u32 i;

  *index = i = b->free_list_index;
  return pool_elt_at_index (bm->buffer_free_list_pool, i);
}

void *vlib_set_buffer_free_callback (vlib_main_t *vm, void *fp)
{
  vlib_buffer_main_t * bm = vm->buffer_main;
  void * rv = bm->buffer_free_callback;

  bm->buffer_free_callback = fp;
  return rv;
}

void vnet_buffer_free_dpdk_mb (vlib_buffer_t * b) __attribute__ ((weak));
void vnet_buffer_free_dpdk_mb (vlib_buffer_t * b) { }

static_always_inline void
vlib_buffer_free_inline (vlib_main_t * vm,
                         u32 * buffers,
                         u32 n_buffers,
                         u32 follow_buffer_next)
{
  vlib_buffer_main_t * bm = vm->buffer_main;
  vlib_buffer_free_list_t * fl;
  static u32 * next_to_free[2]; /* smp bad */
  u32 i_next_to_free, * b, * n, * f, fi;
  uword n_left;
  int i;
  static vlib_buffer_free_list_t ** announce_list;
  vlib_buffer_free_list_t * fl0 = 0, * fl1 = 0;
  u32 bi0=(u32)~0, bi1=(u32)~0, fi0, fi1 = (u32)~0;
  u8 free0, free1=0, free_next0, free_next1;
  u32 (*cb)(vlib_main_t * vm, u32 * buffers, u32 n_buffers,
            u32 follow_buffer_next);

  ASSERT(os_get_cpu_number() == 0);
  
  cb = bm->buffer_free_callback;

  if (PREDICT_FALSE (cb != 0))
    n_buffers = (*cb)(vm, buffers, n_buffers, follow_buffer_next);

  if (! n_buffers)
    return;

  /* Use first buffer to get default free list. */
  {
    u32 bi0 = buffers[0];
    vlib_buffer_t * b0;

    b0 = vlib_get_buffer (vm, bi0);
    fl = buffer_get_free_list (vm, b0, &fi);
    if (fl->buffers_added_to_freelist_function)
        vec_add1 (announce_list, fl);
  }

  vec_validate (next_to_free[0], n_buffers - 1);
  vec_validate (next_to_free[1], n_buffers - 1);

  i_next_to_free = 0;
  n_left = n_buffers;
  b = buffers;

 again:
  /* Verify that buffers are known allocated. */
  vlib_buffer_validate_alloc_free (vm, b,
                                   n_left,
                                   VLIB_BUFFER_KNOWN_ALLOCATED);

  vec_add2_aligned (fl->aligned_buffers, f, n_left,
                    /* align */ sizeof (vlib_copy_unit_t));

  n = next_to_free[i_next_to_free];
  while (n_left >= 4)
    {
      vlib_buffer_t * b0, * b1, * binit0, * binit1, dummy_buffers[2];

      bi0 = b[0];
      bi1 = b[1];

      f[0] = bi0;
      f[1] = bi1;
      f += 2;
      b += 2;
      n_left -= 2;

      /* Prefetch buffers for next iteration. */
      vlib_prefetch_buffer_with_index (vm, b[0], WRITE);
      vlib_prefetch_buffer_with_index (vm, b[1], WRITE);

      b0 = vlib_get_buffer (vm, bi0);
      b1 = vlib_get_buffer (vm, bi1);

      free0 = b0->clone_count == 0;
      free1 = b1->clone_count == 0;

      /* Must be before init which will over-write buffer flags. */
      if (follow_buffer_next)
        {
          n[0] = b0->next_buffer;
          free_next0 = free0 && (b0->flags & VLIB_BUFFER_NEXT_PRESENT) != 0;
          n += free_next0;

          n[0] = b1->next_buffer;
          free_next1 = free1 && (b1->flags & VLIB_BUFFER_NEXT_PRESENT) != 0;
          n += free_next1;
        }
      else
        free_next0 = free_next1 = 0;

      /* Must be before init which will over-write buffer free list. */
      fi0 = b0->free_list_index;
      fi1 = b1->free_list_index;

      if (PREDICT_FALSE (fi0 != fi || fi1 != fi))
        goto slow_path_x2;

      binit0 = free0 ? b0 : &dummy_buffers[0];
      binit1 = free1 ? b1 : &dummy_buffers[1];

      vlib_buffer_init_two_for_free_list (binit0, binit1, fl);
      continue;

    slow_path_x2:
      /* Backup speculation. */
      f -= 2;
      n -= free_next0 + free_next1;

      _vec_len (fl->aligned_buffers) = f - fl->aligned_buffers;

      fl0 = pool_elt_at_index (bm->buffer_free_list_pool, fi0);
      fl1 = pool_elt_at_index (bm->buffer_free_list_pool, fi1);

      add_buffer_to_free_list (vm, fl0, bi0, free0);
      if (PREDICT_FALSE(fl0->buffers_added_to_freelist_function != 0))
        {
          int i;
          for (i = 0; i < vec_len (announce_list); i++)
            if (fl0 == announce_list[i])
              goto no_fl0;
          vec_add1(announce_list, fl0);
        }
    no_fl0:
      if (PREDICT_FALSE(fl1->buffers_added_to_freelist_function != 0))
        {
          int i;
          for (i = 0; i < vec_len (announce_list); i++)
            if (fl1 == announce_list[i])
              goto no_fl1;
          vec_add1(announce_list, fl1);
        }

    no_fl1:
      add_buffer_to_free_list (vm, fl1, bi1, free1);

      /* Possibly change current free list. */
      if (fi0 != fi && fi1 != fi)
        {
          fi = fi1;
          fl = pool_elt_at_index (bm->buffer_free_list_pool, fi);
        }

      vec_add2_aligned (fl->aligned_buffers, f, n_left,
                        /* align */ sizeof (vlib_copy_unit_t));
    }

  while (n_left >= 1)
    {
      vlib_buffer_t * b0, * binit0, dummy_buffers[1];

      bi0 = b[0];
      f[0] = bi0;
      f += 1;
      b += 1;
      n_left -= 1;

      b0 = vlib_get_buffer (vm, bi0);

      free0 = b0->clone_count == 0;

      /* Must be before init which will over-write buffer flags. */
      if (follow_buffer_next)
        {
          n[0] = b0->next_buffer;
          free_next0 = free0 && (b0->flags & VLIB_BUFFER_NEXT_PRESENT) != 0;
          n += free_next0;
        }
      else
        free_next0 = 0;

      /* Must be before init which will over-write buffer free list. */
      fi0 = b0->free_list_index;

      if (PREDICT_FALSE (fi0 != fi))
        goto slow_path_x1;

      binit0 = free0 ? b0 : &dummy_buffers[0];

      vlib_buffer_init_for_free_list (binit0, fl);
      continue;

    slow_path_x1:
      /* Backup speculation. */
      f -= 1;
      n -= free_next0;

      _vec_len (fl->aligned_buffers) = f - fl->aligned_buffers;

      fl0 = pool_elt_at_index (bm->buffer_free_list_pool, fi0);

      add_buffer_to_free_list (vm, fl0, bi0, free0);
      if (PREDICT_FALSE(fl0->buffers_added_to_freelist_function != 0))
        {
          int i;
          for (i = 0; i < vec_len (announce_list); i++)
            if (fl0 == announce_list[i])
              goto no_fl00;
          vec_add1(announce_list, fl0);
        }
      
    no_fl00:
      fi = fi0;
      fl = pool_elt_at_index (bm->buffer_free_list_pool, fi);

      vec_add2_aligned (fl->aligned_buffers, f, n_left,
                        /* align */ sizeof (vlib_copy_unit_t));
    }

  if (follow_buffer_next && ((n_left = n - next_to_free[i_next_to_free]) > 0))
    {
      b = next_to_free[i_next_to_free];
      i_next_to_free ^= 1;
      goto again;
    }

  _vec_len (fl->aligned_buffers) = f - fl->aligned_buffers;

  if (vec_len(announce_list))
    {
      vlib_buffer_free_list_t * fl;
      for (i = 0; i < vec_len (announce_list); i++)
        {
          fl = announce_list[i];
          fl->buffers_added_to_freelist_function (vm, fl);
        }
      _vec_len(announce_list) = 0;
    }
}

void vlib_buffer_free (vlib_main_t * vm,
                       u32 * buffers,
                       u32 n_buffers)
{
  vlib_buffer_free_inline (vm, buffers, n_buffers, /* follow_buffer_next */ 1);
}

void vlib_buffer_free_no_next (vlib_main_t * vm,
                               u32 * buffers,
                               u32 n_buffers)
{
  vlib_buffer_free_inline (vm, buffers, n_buffers, /* follow_buffer_next */ 0);
}

/* Copy template packet data into buffers as they are allocated. */
static void
vlib_packet_template_buffer_init (vlib_main_t * vm,
                                  vlib_buffer_free_list_t * fl,
                                  u32 * buffers,
                                  u32 n_buffers)
{
  vlib_packet_template_t * t = uword_to_pointer (fl->buffer_init_function_opaque,
                                                 vlib_packet_template_t *);
  uword i;

  for (i = 0; i < n_buffers; i++)
    {
      vlib_buffer_t * b = vlib_get_buffer (vm, buffers[i]);
      ASSERT (b->current_length == vec_len (t->packet_data));
      clib_memcpy (vlib_buffer_get_current (b), t->packet_data, b->current_length);
    }
}

void vlib_packet_template_init (vlib_main_t * vm,
                                vlib_packet_template_t * t,
                                void * packet_data,
                                uword n_packet_data_bytes,
                                uword min_n_buffers_each_physmem_alloc,
                                char * fmt,
                                ...)
{
  vlib_buffer_free_list_t * fl;
  va_list va;
  u8 * name;

  va_start (va, fmt);
  name = va_format (0, fmt, &va);
  va_end (va);

  memset (t, 0, sizeof (t[0]));

  vec_add (t->packet_data, packet_data, n_packet_data_bytes);
  t->min_n_buffers_each_physmem_alloc = min_n_buffers_each_physmem_alloc;

  t->free_list_index = vlib_buffer_create_free_list_helper
    (vm, n_packet_data_bytes,
     /* is_public */ 1,
     /* is_default */ 0,
     name);

  ASSERT (t->free_list_index != 0);
  fl = vlib_buffer_get_free_list (vm, t->free_list_index);
  fl->min_n_buffers_each_physmem_alloc = t->min_n_buffers_each_physmem_alloc;

  fl->buffer_init_function = vlib_packet_template_buffer_init;
  fl->buffer_init_function_opaque = pointer_to_uword (t);

  fl->buffer_init_template.current_data = 0;
  fl->buffer_init_template.current_length = n_packet_data_bytes;
  fl->buffer_init_template.flags = 0;
}

void *
vlib_packet_template_get_packet (vlib_main_t * vm, 
                                 vlib_packet_template_t * t, 
                                 u32 * bi_result)
{
  u32 bi;
  vlib_buffer_t * b;

  if (vlib_buffer_alloc (vm, &bi, 1) != 1)
    return 0;

  *bi_result = bi;

  b = vlib_get_buffer (vm, bi);
  clib_memcpy (vlib_buffer_get_current (b),
          t->packet_data, vec_len(t->packet_data));
  b->current_length = vec_len(t->packet_data);

  return b->data;
}

void vlib_packet_template_get_packet_helper (vlib_main_t * vm, vlib_packet_template_t * t)
{
  word n = t->min_n_buffers_each_physmem_alloc;
  word l = vec_len (t->packet_data);
  word n_alloc;

  ASSERT (l > 0);
  ASSERT (vec_len (t->free_buffers) == 0);

  vec_validate (t->free_buffers, n - 1);
  n_alloc = vlib_buffer_alloc_from_free_list (vm, t->free_buffers,
                                              n, t->free_list_index);
  _vec_len (t->free_buffers) = n_alloc;
}

/* Append given data to end of buffer, possibly allocating new buffers. */
u32 vlib_buffer_add_data (vlib_main_t * vm,
                          u32 free_list_index,
                          u32 buffer_index,
                          void * data, u32 n_data_bytes)
{
  u32 n_buffer_bytes, n_left, n_left_this_buffer, bi;
  vlib_buffer_t * b;
  void * d;

  bi = buffer_index;
  if (bi == 0
      && 1 != vlib_buffer_alloc_from_free_list (vm, &bi, 1, free_list_index))
    goto out_of_buffers;

  d = data;
  n_left = n_data_bytes;
  n_buffer_bytes = vlib_buffer_free_list_buffer_size (vm, free_list_index);
  
  b = vlib_get_buffer (vm, bi);
  b->flags &= ~VLIB_BUFFER_TOTAL_LENGTH_VALID;

  /* Get to the end of the chain before we try to append data...*/
  while (b->flags & VLIB_BUFFER_NEXT_PRESENT)
    b = vlib_get_buffer (vm, b->next_buffer);

  while (1)
    {
      u32 n;

      ASSERT (n_buffer_bytes >= b->current_length);
      n_left_this_buffer = n_buffer_bytes - (b->current_data + b->current_length);
      n = clib_min (n_left_this_buffer, n_left);
      clib_memcpy (vlib_buffer_get_current (b) + b->current_length, d, n);
      b->current_length += n;
      n_left -= n;
      if (n_left == 0)
        break;

      d += n;
      if (1 != vlib_buffer_alloc_from_free_list (vm, &b->next_buffer, 1, free_list_index))
        goto out_of_buffers;

      b->flags |= VLIB_BUFFER_NEXT_PRESENT;

      b = vlib_get_buffer (vm, b->next_buffer);
    }

  return bi;

 out_of_buffers:
  clib_error ("out of buffers");
  return bi;
}

u16
vlib_buffer_chain_append_data_with_alloc(vlib_main_t *vm,
                             u32 free_list_index,
                             vlib_buffer_t *first,
                             vlib_buffer_t **last,
                             void * data, u16 data_len) {
  vlib_buffer_t *l = *last;
  u32 n_buffer_bytes = vlib_buffer_free_list_buffer_size (vm, free_list_index);
  u16 copied = 0;
  ASSERT(n_buffer_bytes >= l->current_length + l->current_data);
  while (data_len) {
    u16 max = n_buffer_bytes - l->current_length - l->current_data;
    if (max == 0) {
      if (1 != vlib_buffer_alloc_from_free_list (vm, &l->next_buffer, 1, free_list_index))
        return copied;
      *last = l = vlib_buffer_chain_buffer(vm, first, l, l->next_buffer);
      max = n_buffer_bytes - l->current_length - l->current_data;
    }

    u16 len = (data_len > max)?max:data_len;
    clib_memcpy(vlib_buffer_get_current (l) + l->current_length, data + copied, len);
    vlib_buffer_chain_increase_length(first, l, len);
    data_len -= len;
    copied += len;
  }
  return copied;
}

/*
 * Fills in the required rte_mbuf fields for chained buffers given a VLIB chain.
 */
void vlib_buffer_chain_validate (vlib_main_t * vm, vlib_buffer_t * b_first)
{
  return;
}

static void vlib_serialize_tx (serialize_main_header_t * m, serialize_stream_t * s)
{
  vlib_main_t * vm;
  vlib_serialize_buffer_main_t * sm;
  uword n, n_bytes_to_write;
  vlib_buffer_t * last;

  n_bytes_to_write = s->current_buffer_index;
  sm = uword_to_pointer (s->data_function_opaque, vlib_serialize_buffer_main_t *);
  vm = sm->vlib_main;

  ASSERT (sm->tx.max_n_data_bytes_per_chain > 0);
  if (serialize_stream_is_end_of_stream (s)
      || sm->tx.n_total_data_bytes + n_bytes_to_write > sm->tx.max_n_data_bytes_per_chain)
    {
      vlib_process_t * p = vlib_get_current_process (vm);

      last = vlib_get_buffer (vm, sm->last_buffer);
      last->current_length = n_bytes_to_write;

      vlib_set_next_frame_buffer (vm, &p->node_runtime, sm->tx.next_index, sm->first_buffer);

      sm->first_buffer = sm->last_buffer = ~0;
      sm->tx.n_total_data_bytes = 0;
    }

  else if (n_bytes_to_write == 0 && s->n_buffer_bytes == 0)
    {
      ASSERT (sm->first_buffer == ~0);
      ASSERT (sm->last_buffer == ~0);
      n = vlib_buffer_alloc_from_free_list (vm, &sm->first_buffer, 1, sm->tx.free_list_index);
      if (n != 1)
        serialize_error (m, clib_error_create ("vlib_buffer_alloc_from_free_list fails"));
      sm->last_buffer = sm->first_buffer;
      s->n_buffer_bytes = vlib_buffer_free_list_buffer_size (vm, sm->tx.free_list_index);
    }

  if (n_bytes_to_write > 0)
    {
      vlib_buffer_t * prev = vlib_get_buffer (vm, sm->last_buffer);
      n = vlib_buffer_alloc_from_free_list (vm, &sm->last_buffer, 1, sm->tx.free_list_index);
      if (n != 1)
        serialize_error (m, clib_error_create ("vlib_buffer_alloc_from_free_list fails"));
      sm->tx.n_total_data_bytes += n_bytes_to_write;
      prev->current_length = n_bytes_to_write;
      prev->next_buffer = sm->last_buffer;
      prev->flags |= VLIB_BUFFER_NEXT_PRESENT;
    }

  if (sm->last_buffer != ~0)
    {
      last = vlib_get_buffer (vm, sm->last_buffer);
      s->buffer = vlib_buffer_get_current (last);
      s->current_buffer_index = 0;
      ASSERT (last->current_data == s->current_buffer_index);
    }
}

static void vlib_serialize_rx (serialize_main_header_t * m, serialize_stream_t * s)
{
  vlib_main_t * vm;
  vlib_serialize_buffer_main_t * sm;
  vlib_buffer_t * last;

  sm = uword_to_pointer (s->data_function_opaque, vlib_serialize_buffer_main_t *);
  vm = sm->vlib_main;

  if (serialize_stream_is_end_of_stream (s))
    return;

  if (sm->last_buffer != ~0)
    {
      last = vlib_get_buffer (vm, sm->last_buffer);

      if (last->flags & VLIB_BUFFER_NEXT_PRESENT)
        sm->last_buffer = last->next_buffer;
      else
        {
          vlib_buffer_free (vm, &sm->first_buffer, /* count */ 1);
          sm->first_buffer = sm->last_buffer = ~0;
        }
    }

  if (sm->last_buffer == ~0)
    {
      while (clib_fifo_elts (sm->rx.buffer_fifo) == 0)
        {
          sm->rx.ready_one_time_event = vlib_process_create_one_time_event (vm, vlib_current_process (vm), ~0);
          vlib_process_wait_for_one_time_event (vm, /* no event data */ 0, sm->rx.ready_one_time_event);
        }

      clib_fifo_sub1 (sm->rx.buffer_fifo, sm->first_buffer);
      sm->last_buffer = sm->first_buffer;
    }

  ASSERT (sm->last_buffer != ~0);

  last = vlib_get_buffer (vm, sm->last_buffer);
  s->current_buffer_index = 0;
  s->buffer = vlib_buffer_get_current (last);
  s->n_buffer_bytes = last->current_length;
}

static void
serialize_open_vlib_helper (serialize_main_t * m,
                            vlib_main_t * vm,
                            vlib_serialize_buffer_main_t * sm,
                            uword is_read)
{
  /* Initialize serialize main but save overflow buffer for re-use between calls. */
  {
    u8 * save = m->stream.overflow_buffer;
    memset (m, 0, sizeof (m[0]));
    m->stream.overflow_buffer = save;
    if (save)
      _vec_len (save) = 0;
  }

  sm->first_buffer = sm->last_buffer = ~0;
  if (is_read)
    clib_fifo_reset (sm->rx.buffer_fifo);
  else
    sm->tx.n_total_data_bytes = 0;
  sm->vlib_main = vm;
  m->header.data_function = is_read ? vlib_serialize_rx : vlib_serialize_tx;
  m->stream.data_function_opaque = pointer_to_uword (sm);
}

void serialize_open_vlib_buffer (serialize_main_t * m, vlib_main_t * vm, vlib_serialize_buffer_main_t * sm)
{ serialize_open_vlib_helper (m, vm, sm, /* is_read */ 0); }

void unserialize_open_vlib_buffer (serialize_main_t * m, vlib_main_t * vm, vlib_serialize_buffer_main_t * sm)
{ serialize_open_vlib_helper (m, vm, sm, /* is_read */ 1); }

u32 serialize_close_vlib_buffer (serialize_main_t * m)
{
  vlib_serialize_buffer_main_t * sm
    = uword_to_pointer (m->stream.data_function_opaque, vlib_serialize_buffer_main_t *);
  vlib_buffer_t * last;
  serialize_stream_t * s = &m->stream;

  last = vlib_get_buffer (sm->vlib_main, sm->last_buffer);
  last->current_length = s->current_buffer_index;

  if (vec_len (s->overflow_buffer) > 0)
    {
      sm->last_buffer
        = vlib_buffer_add_data (sm->vlib_main, sm->tx.free_list_index,
                                sm->last_buffer == ~0 ? 0 : sm->last_buffer,
                                s->overflow_buffer,
                                vec_len (s->overflow_buffer));
      _vec_len (s->overflow_buffer) = 0;
    }

  return sm->first_buffer;
}

void unserialize_close_vlib_buffer (serialize_main_t * m)
{
  vlib_serialize_buffer_main_t * sm
    = uword_to_pointer (m->stream.data_function_opaque, vlib_serialize_buffer_main_t *);
  if (sm->first_buffer != ~0)
    vlib_buffer_free_one (sm->vlib_main, sm->first_buffer);
  clib_fifo_reset (sm->rx.buffer_fifo);
  if (m->stream.overflow_buffer)
    _vec_len (m->stream.overflow_buffer) = 0;
}

static u8 * format_vlib_buffer_free_list (u8 * s, va_list * va)
{
  vlib_buffer_free_list_t * f = va_arg (*va, vlib_buffer_free_list_t *);
  uword bytes_alloc, bytes_free, n_free, size;

  if (! f)
    return format (s, "%=30s%=12s%=12s%=12s%=12s%=12s%=12s",
                   "Name", "Index", "Size", "Alloc", "Free", "#Alloc", "#Free");

  size = sizeof (vlib_buffer_t) + f->n_data_bytes;
  n_free = vec_len (f->aligned_buffers) + vec_len (f->unaligned_buffers);
  bytes_alloc = size * f->n_alloc;
  bytes_free = size * n_free;

  s = format (s, "%30s%12d%12d%=12U%=12U%=12d%=12d",
              f->name, f->index, f->n_data_bytes,
              format_memory_size, bytes_alloc,
              format_memory_size, bytes_free,
              f->n_alloc, n_free);

  return s;
}

static clib_error_t *
show_buffers (vlib_main_t * vm,
              unformat_input_t * input,
              vlib_cli_command_t * cmd)
{
  vlib_buffer_main_t * bm = vm->buffer_main;
  vlib_buffer_free_list_t * f;

  vlib_cli_output (vm, "%U", format_vlib_buffer_free_list, 0);
  pool_foreach (f, bm->buffer_free_list_pool, ({
    vlib_cli_output (vm, "%U", format_vlib_buffer_free_list, f);
  }));

  return 0;
}

VLIB_CLI_COMMAND (show_buffers_command, static) = {
  .path = "show buffers",
  .short_help = "Show packet buffer allocation",
  .function = show_buffers,
};