pbuf.c

网络服务器上实现操作系统和嵌入式协议栈的 结合

/**
 * @file
 * Packet buffer management
 *
 * Packets are represented by the pbuf data structure. It supports dynamic
 * memory allocation for packet contents or can reference externally
 * managed packet contents both in RAM and ROM. Quick allocation for
 * incoming packets is provided through pools with fixed sized pbufs.
 *
 * Pbufs can be chained as a singly linked list, called a pbuf chain, so
 * that a packet may span over several pbufs.
 *
 */

/*
 * Copyright (c) 2001-2003 Swedish Institute of Computer Science.
 * All rights reserved. 
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
 * OF SUCH DAMAGE.
 *
 * This file is part of the lwIP TCP/IP stack.
 * 
 * Author: Adam Dunkels <[e-mail]>
 *
 */

#include "lwip/opt.h"

#include "lwip/stats.h"

#include "lwip/def.h"
#include "lwip/mem.h"
#include "lwip/memp.h"
#include "lwip/pbuf.h"

#include "lwip/sys.h"

#include "arch/perf.h"
//added by dy
#include <string.h>


static u8_t pbuf_pool_memory[(PBUF_POOL_SIZE * MEM_ALIGN_SIZE(PBUF_POOL_BUFSIZE + sizeof(struct pbuf)))];

#if !SYS_LIGHTWEIGHT_PROT
static volatile u8_t pbuf_pool_free_lock, pbuf_pool_alloc_lock;
static sys_sem_t pbuf_pool_free_sem;
#endif

static struct pbuf *pbuf_pool = NULL;
static struct pbuf *pbuf_pool_alloc_cache = NULL;
static struct pbuf *pbuf_pool_free_cache = NULL;


/**
 * Initializes the pbuf module.
 *
 * A large part of memory is allocated for holding the pool of pbufs.
 * The size of the individual pbufs in the pool is given by the size
 * parameter, and the number of pbufs in the pool by the num parameter.
 *
 * After the memory has been allocated, the pbufs are set up. The
 * ->next pointer in each pbuf is set up to point to the next pbuf in
 * the pool.
 *
 */
void
pbuf_init(void)
{
  struct pbuf *p, *q = NULL;
  u16_t i;

  pbuf_pool = (struct pbuf *)&pbuf_pool_memory[0];
  LWIP_ASSERT("pbuf_init: pool aligned", (long)pbuf_pool % MEM_ALIGNMENT == 0);
   
#ifdef PBUF_STATS
  lwip_stats.pbuf.avail = PBUF_POOL_SIZE;
#endif /* PBUF_STATS */
  
  /* Set up ->next pointers to link the pbufs of the pool together */
  p = pbuf_pool;
  
  for(i = 0; i < PBUF_POOL_SIZE; ++i) {
    p->next = (struct pbuf *)((u8_t *)p + PBUF_POOL_BUFSIZE + sizeof(struct pbuf));
    p->len = p->tot_len = PBUF_POOL_BUFSIZE;
    p->payload = MEM_ALIGN((void *)((u8_t *)p + sizeof(struct pbuf)));
    q = p;
    p = p->next;
  }
  
  /* The ->next pointer of last pbuf is NULL to indicate that there
     are no more pbufs in the pool */
  q->next = NULL;

#if !SYS_LIGHTWEIGHT_PROT  
  pbuf_pool_alloc_lock = 0;
  pbuf_pool_free_lock = 0;
  pbuf_pool_free_sem = sys_sem_new(1);
#endif  
}



/**
 * @internal only called from pbuf_alloc()
 */

static void
pbuf_pool_free(struct pbuf *p)
{
  struct pbuf *q;
//丁一修改
#if SYS_LIGHTWEIGHT_PROT
  SYS_ARCH_DECL_PROTECT(old_level);
  SYS_ARCH_PROTECT(old_level);
#else /* SYS_LIGHTWEIGHT_PROT */  
  sys_sem_wait(pbuf_pool_free_sem);
#endif /* SYS_LIGHTWEIGHT_PROT */  
//原本
//  SYS_ARCH_DECL_PROTECT(old_level);
// SYS_ARCH_PROTECT(old_level); 

#ifdef PBUF_STATS
    for(q = p; q != NULL; q = q->next) {
      --lwip_stats.pbuf.used;
    }
#endif /* PBUF_STATS */

  if(pbuf_pool_alloc_cache == NULL) {
    pbuf_pool_alloc_cache = p;
  } else {  
    for(q = pbuf_pool_alloc_cache; q->next != NULL; q = q->next);
    q->next = p;    
  }

//丁一修改  
#if SYS_LIGHTWEIGHT_PROT
  SYS_ARCH_UNPROTECT(old_level);
#else /* SYS_LIGHTWEIGHT_PROT */
  sys_sem_signal(pbuf_pool_free_sem);
#endif /* SYS_LIGHTWEIGHT_PROT */  
//原本  
//  SYS_ARCH_UNPROTECT(old_level);  
}

/**
 * @internal only called from pbuf_alloc()
 */

static struct pbuf *
pbuf_pool_alloc(void)
{
  struct pbuf *p = NULL;

//丁一修改
#if SYS_LIGHTWEIGHT_PROT
  SYS_ARCH_DECL_PROTECT(old_level);
  SYS_ARCH_PROTECT(old_level);
#else /* SYS_LIGHTWEIGHT_PROT */  
  sys_sem_wait(pbuf_pool_free_sem);
#endif /* SYS_LIGHTWEIGHT_PROT */  
//原本
//  SYS_ARCH_DECL_PROTECT(old_level);
//  SYS_ARCH_PROTECT(old_level); 

  /* First, see if there are pbufs in the cache. */
  
  if(pbuf_pool_alloc_cache) {
    p = pbuf_pool_alloc_cache;
    if(p) {
      pbuf_pool_alloc_cache = p->next; 
    }
  } else {
#if !SYS_LIGHTWEIGHT_PROT      
    /* Next, check the actual pbuf pool, but if the pool is locked, we
       pretend to be out of buffers and return NULL. */
    if(pbuf_pool_free_lock) {
#ifdef PBUF_STATS
      ++lwip_stats.pbuf.alloc_locked;
#endif /* PBUF_STATS */
      return NULL;
    }
    pbuf_pool_alloc_lock = 1;
    if(!pbuf_pool_free_lock) {
#endif /* SYS_LIGHTWEIGHT_PROT */        
      p = pbuf_pool;
      if(p) {
	pbuf_pool = p->next; 
      }
#if !SYS_LIGHTWEIGHT_PROT      
#ifdef PBUF_STATS
    } else {
      ++lwip_stats.pbuf.alloc_locked;
#endif /* PBUF_STATS */
    }
    pbuf_pool_alloc_lock = 0;
#endif /* SYS_LIGHTWEIGHT_PROT */    
  }
  
#ifdef PBUF_STATS
  if(p != NULL) {    
    ++lwip_stats.pbuf.used;
    if(lwip_stats.pbuf.used > lwip_stats.pbuf.max) {
      lwip_stats.pbuf.max = lwip_stats.pbuf.used;
    }
  }
#endif /* PBUF_STATS */

  //丁一修改  
#if SYS_LIGHTWEIGHT_PROT
  SYS_ARCH_UNPROTECT(old_level);
#else /* SYS_LIGHTWEIGHT_PROT */
  sys_sem_signal(pbuf_pool_free_sem);
#endif /* SYS_LIGHTWEIGHT_PROT */  
//原本  
//  SYS_ARCH_UNPROTECT(old_level);  

  return p;   
}


/**
 * Allocates a pbuf.
 *
 * The actual memory allocated for the pbuf is determined by the
 * layer at which the pbuf is allocated and the requested size
 * (from the size parameter).
 *
 * @param flag this parameter decides how and where the pbuf
 * should be allocated as follows:
 * 
 * - PBUF_RAM: buffer memory for pbuf is allocated as one large
 *             chunk. This includes protocol headers as well. 
 * - PBUF_ROM: no buffer memory is allocated for the pbuf, even for
 *             protocol headers. Additional headers must be prepended
 *             by allocating another pbuf and chain in to the front of
 *             the ROM pbuf. It is assumed that the memory used is really
 *             similar to ROM in that it is immutable and will not be
 *             changed. Memory which is dynamic should generally not
 *             be attached to PBUF_ROM pbufs. Use PBUF_REF instead.
 * - PBUF_REF: no buffer memory is allocated for the pbuf, even for
 *             protocol headers. It is assumed that the pbuf is only
 *             being used in a single thread. If the pbuf gets queued,
 *             then pbuf_take should be called to copy the buffer.
 * - PBUF_POOL: the pbuf is allocated as a pbuf chain, with pbufs from
 *              the pbuf pool that is allocated during pbuf_init().
 *
 * @return the allocated pbuf. If multiple pbufs where allocated, this
 * is the first pbuf of a pbuf chain. 
 */
struct pbuf *
pbuf_alloc(pbuf_layer l, u16_t length, pbuf_flag flag)
{
  struct pbuf *p, *q, *r;
  u16_t offset;
  s32_t rem_len; /* remaining length */

  /* determine header offset */
  offset = 0;
  switch (l) {
  case PBUF_TRANSPORT:
    /* add room for transport (often TCP) layer header */
    offset += PBUF_TRANSPORT_HLEN;
    /* FALLTHROUGH */
  case PBUF_IP:
    /* add room for IP layer header */
    offset += PBUF_IP_HLEN;
    /* FALLTHROUGH */
  case PBUF_LINK:
    /* add room for link layer header */
    offset += PBUF_LINK_HLEN;
    break;
  case PBUF_RAW:
    break;
  default:
    LWIP_ASSERT("pbuf_alloc: bad pbuf layer", 0);
    return NULL;
  }

  switch (flag) {
  case PBUF_POOL:
    /* allocate head of pbuf chain into p */
    p = pbuf_pool_alloc();
    if (p == NULL) {
#ifdef PBUF_STATS
      ++lwip_stats.pbuf.err;
#endif /* PBUF_STATS */
      return NULL;
    }
    p->next = NULL;
    
    /* make the payload pointer point 'offset' bytes into pbuf data memory */
    p->payload = MEM_ALIGN((void *)((u8_t *)p + (sizeof(struct pbuf) + offset)));
    LWIP_ASSERT("pbuf_alloc: pbuf p->payload properly aligned",
	    ((u32_t)p->payload % MEM_ALIGNMENT) == 0);
    /* the total length of the pbuf chain is the requested size */
    p->tot_len = length;
    /* set the length of the first pbuf in the chain */
    p->len = length > PBUF_POOL_BUFSIZE - offset? PBUF_POOL_BUFSIZE - offset: length;
    /* set pbuf type */
    p->flags = PBUF_FLAG_POOL;
    
    /* now allocate the tail of the pbuf chain */
    
    /* remember first pbuf for linkage in next iteration */
    r = p;
    /* remaining length to be allocated */
    rem_len = length - p->len;
    /* any remaining pbufs to be allocated? */
    while(rem_len > 0) {      
      q = pbuf_pool_alloc();
      if (q == NULL) {
       DEBUGF(PBUF_DEBUG | 2, ("pbuf_alloc: Out of pbufs in pool.\n"));