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Corrected more pbuf.c functions to comply with pbuf->ref and ->tot_len invariant.

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likewise 2003-03-30 22:24:10 +00:00
parent 2bd3d51fcf
commit c50f80da92
2 changed files with 192 additions and 258 deletions
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440
src/core/pbuf.c
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@ -2,6 +2,7 @@
* @file
* Packet buffers/chains management module
*/
/*
* Copyright (c) 2001-2003 Swedish Institute of Computer Science.
* All rights reserved.
@ -34,9 +35,6 @@
*
*/
#define NEW_PBUF_REALLOC 1 /* enabling this should fix bug #1903 */
#define PBUF_CHAIN_DOES_REFER 1 /** enabling this fixes bug #2968 */
#include "lwip/opt.h"
#include "lwip/stats.h"
@ -61,23 +59,23 @@ static struct pbuf *pbuf_pool = NULL;
static struct pbuf *pbuf_pool_alloc_cache = NULL;
static struct pbuf *pbuf_pool_free_cache = NULL;
/*-----------------------------------------------------------------------------------*/
/* pbuf_init():
/**
*
* 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.
* 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 = 0;
struct pbuf *p, *q = NULL;
u16_t i;
pbuf_pool = (struct pbuf *)&pbuf_pool_memory[0];
@ -108,9 +106,10 @@ pbuf_init(void)
pbuf_pool_free_sem = sys_sem_new(1);
#endif
}
/*-----------------------------------------------------------------------------------*/
/* The following two functions are only called from pbuf_alloc(). */
/*-----------------------------------------------------------------------------------*/
/**
* @internal only called from pbuf_alloc()
*/
static struct pbuf *
pbuf_pool_alloc(void)
{
@ -163,7 +162,10 @@ pbuf_pool_alloc(void)
SYS_ARCH_UNPROTECT(old_level);
return p;
}
/*-----------------------------------------------------------------------------------*/
/**
* @internal only called from pbuf_alloc()
*/
static void
pbuf_pool_free(struct pbuf *p)
{
@ -185,42 +187,41 @@ pbuf_pool_free(struct pbuf *p)
}
SYS_ARCH_UNPROTECT(old_level);
}
/*-----------------------------------------------------------------------------------*/
/* pbuf_alloc():
/**
*
* Allocates a pbuf at protocol layer l. 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). The
* flag parameter decides how and where the pbuf should be allocated
* as follows:
* Allocates a pbuf at protocol layer l.
* 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). The flag parameter decides how and
* where the pbuf should be allocated as follows:
*
* * PBUF_RAM: buffer memory for pbuf is allocated as one large
* - 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
* - 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
* - 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
* - PBUF_POOL: the pbuf is allocated as a pbuf chain, with pbufs from
* the pbuf pool that is allocated during pbuf_init().
*/
/*-----------------------------------------------------------------------------------*/
struct pbuf *
pbuf_alloc(pbuf_layer l, u16_t size, pbuf_flag flag)
{
struct pbuf *p, *q, *r;
u16_t offset;
s32_t rsize;
s32_t rem_len;
/* determine header offset */
offset = 0;
switch(l) {
switch (l) {
case PBUF_TRANSPORT:
offset += PBUF_TRANSPORT_HLEN;
/* FALLTHROUGH */
@ -237,11 +238,11 @@ pbuf_alloc(pbuf_layer l, u16_t size, pbuf_flag flag)
return NULL;
}
switch(flag) {
switch (flag) {
case PBUF_POOL:
/* allocate head of pbuf chain into p */
p = pbuf_pool_alloc();
if(p == NULL) {
if (p == NULL) {
#ifdef PBUF_STATS
++lwip_stats.pbuf.err;
#endif /* PBUF_STATS */
@ -251,36 +252,34 @@ pbuf_alloc(pbuf_layer l, u16_t size, pbuf_flag flag)
/* make the payload pointer points offset bytes into pbuf data memory */
p->payload = MEM_ALIGN((void *)((u8_t *)p + (sizeof(struct pbuf) + offset)));
/* the total length of the pbuf is the requested size */
p->tot_len = size;
/* set the length of the first pbuf is the chain */
p->len = size > PBUF_POOL_BUFSIZE - offset? PBUF_POOL_BUFSIZE - offset: size;
p->flags = PBUF_FLAG_POOL;
/* allocate the tail of the pbuf chain. */
r = p;
rsize = size - p->len;
while(rsize > 0) {
rem_len = size - p->len;
while(rem_len > 0) {
q = pbuf_pool_alloc();
if (q == NULL) {
DEBUGF(PBUF_DEBUG | 2, ("pbuf_alloc: Out of pbufs in pool.\n"));
#ifdef PBUF_STATS
++lwip_stats.pbuf.err;
#endif /* PBUF_STATS */
/* bail out unsuccesfully */
pbuf_pool_free(p);
return NULL;
}
q->next = NULL;
r->next = q;
q->len = rsize > PBUF_POOL_BUFSIZE? PBUF_POOL_BUFSIZE: rsize;
q->len = rem_len > PBUF_POOL_BUFSIZE? PBUF_POOL_BUFSIZE: rem_len;
q->flags = PBUF_FLAG_POOL;
q->payload = (void *)((u8_t *)q + sizeof(struct pbuf));
r = q;
q->ref = 1;
rsize -= PBUF_POOL_BUFSIZE;
rem_len -= PBUF_POOL_BUFSIZE;
}
/* end of chain */
r->next = NULL;
@ -291,7 +290,7 @@ pbuf_alloc(pbuf_layer l, u16_t size, pbuf_flag flag)
case PBUF_RAM:
/* If pbuf is to be allocated in RAM, allocate memory for it. */
p = mem_malloc(MEM_ALIGN_SIZE(sizeof(struct pbuf) + size + offset));
if(p == NULL) {
if (p == NULL) {
return NULL;
}
/* Set up internal structure of the pbuf. */
@ -309,11 +308,11 @@ pbuf_alloc(pbuf_layer l, u16_t size, pbuf_flag flag)
case PBUF_REF:
/* only allocate memory for the pbuf structure */
p = memp_mallocp(MEMP_PBUF);
if(p == NULL) {
if (p == NULL) {
DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_alloc: Could not allocate MEMP_PBUF for PBUF_REF.\n"));
return NULL;
}
/* caller must set this field properly, afterwards */
/* caller must set this field properly, afterwards */
p->payload = NULL;
p->len = p->tot_len = size;
p->next = NULL;
@ -326,14 +325,13 @@ pbuf_alloc(pbuf_layer l, u16_t size, pbuf_flag flag)
p->ref = 1;
return p;
}
/*-----------------------------------------------------------------------------------*/
/* pbuf_refresh():
/**
*
* Moves free buffers from the pbuf_pool_free_cache to the pbuf_pool
* list (if possible).
*
*/
/*-----------------------------------------------------------------------------------*/
void
pbuf_refresh(void)
{
@ -401,24 +399,19 @@ pbuf_refresh(void)
#endif /* SYS_LIGHTWEIGHT_PROT */
/**
* Shrink a pbuf chain to a certain size.
* Shrink a pbuf chain to a desired length.
*
* @param p pbuf to shrink.
* @param size new size
* @param new_len desired new length of pbuf chain
*
* Depending on the desired size, the first few pbufs in a chain might
* be skipped.
* Depending on the desired length, the first few pbufs in a chain might
* be skipped and left unchanged. The new last pbuf in the chain will be
* resized, and any remaining pbufs will be freed.
*
* @note If the pbuf is ROM/REF, only the ->tot_len and ->len fields are adjusted.
* If the chain
* a pbuf chain, as it might be with both pbufs in dynamically
* allocated RAM and for pbufs from the pbuf pool, we have to step
* through the chain until we find the new endpoint in the pbuf chain.
* Then the pbuf that is right on the endpoint is resized and any
* further pbufs on the chain are deallocated.
* @bug Cannot grow the size of a pbuf (chain).
*
* @bug Cannot grow the size of a pbuf (chain) (yet).
*/
/*-----------------------------------------------------------------------------------*/
#if NEW_PBUF_REALLOC
void
pbuf_realloc(struct pbuf *p, u16_t new_len)
{
@ -431,12 +424,14 @@ pbuf_realloc(struct pbuf *p, u16_t new_len)
p->flags == PBUF_FLAG_RAM ||
p->flags == PBUF_FLAG_REF);
/* desired length larger than current length? */
if (new_len >= p->tot_len) {
/** enlarging not yet supported */
/* enlarging not yet supported */
return;
}
/* { the pbuf chains grows by (new_len - p->tot_len) bytes } */
/* the pbuf chain grows by (new_len - p->tot_len) bytes
* (which may be negative in case of shrinking) */
grow = new_len - p->tot_len;
/* first, step over any pbufs that should remain in the chain */
@ -446,120 +441,37 @@ pbuf_realloc(struct pbuf *p, u16_t new_len)
while (rem_len > q->len) {
/* decrease remaining length by pbuf length */
rem_len -= q->len;
/* decrease total length indicator */
q->tot_len += grow;
/* proceed to next pbuf in chain */
q = q->next;
}
/* { we have now reached the new last pbuf } */
/* { rem_len == desired length for pbuf q } */
/* we have now reached the new last pbuf (in q) */
/* rem_len == desired length for pbuf q */
/* shrink allocated memory for PBUF_RAM */
/* (other types merely adjust their length fields */
if ((q->flags == PBUF_FLAG_RAM) && (rem_len != q->len )) {
if ((q->flags == PBUF_FLAG_RAM) && (rem_len != q->len)) {
/* reallocate and adjust the length of the pbuf that will be split */
mem_realloc(q, (u8_t *)q->payload - (u8_t *)q + rem_len);
}
/* adjust length fields */
/* adjust length fields for new last pbuf */
q->len = rem_len;
q->tot_len = q->len;
/* deallocate any left over pbufs */
/* remember next pbuf in chain */
r = q->next;
/* any remaining pbufs in chain? */
if (q->next != NULL) {
/* free remaining pbufs in chain */
pbuf_free(q->next);
}
/* q is last packet in chain */
q->next = NULL;
/* first pbuf to be dealloced */
q = r;
/* any pbuf left? */
while(q != NULL) {
/* remember next pbuf in chain */
r = q->next;
/* deallocate pbuf */
if (q->flags == PBUF_FLAG_POOL) {
PBUF_POOL_FREE(q);
} else {
pbuf_free(q);
}
q = r;
}
pbuf_refresh();
}
#else /* pbuf_realloc() of CVS version 1.23 */
void
pbuf_realloc(struct pbuf *p, u16_t size)
{
struct pbuf *q, *r;
u16_t rsize;
LWIP_ASSERT("pbuf_realloc: sane p->flags", p->flags == PBUF_FLAG_POOL ||
p->flags == PBUF_FLAG_ROM ||
p->flags == PBUF_FLAG_RAM ||
p->flags == PBUF_FLAG_REF);
if(p->tot_len <= size) {
return;
}
switch(p->flags) {
case PBUF_FLAG_POOL:
/* First, step over any pbufs that should still be in the chain. */
rsize = size;
q = p;
while(rsize > q->len) {
rsize -= q->len;
q = q->next;
}
/* Adjust the length of the pbuf that will be halved. */
q->len = rsize;
/* And deallocate any left over pbufs. */
r = q->next;
q->next = NULL;
q = r;
while(q != NULL) {
r = q->next;
PBUF_POOL_FREE(q);
q = r;
}
break;
case PBUF_FLAG_ROM:
case PBUF_FLAG_REF:
p->len = size;
break;
case PBUF_FLAG_RAM:
/* First, step over the pbufs that should still be in the chain. */
rsize = size;
q = p;
while(rsize > q->len) {
rsize -= q->len;
q = q->next;
}
if(q->flags == PBUF_FLAG_RAM) {
/* Reallocate and adjust the length of the pbuf that will be halved. */
mem_realloc(q, (u8_t *)q->payload - (u8_t *)q + rsize);
}
q->len = rsize;
/* And deallocate any left over pbufs. */
r = q->next;
q->next = NULL;
q = r;
while(q != NULL) {
r = q->next;
pbuf_free(q);
q = r;
}
break;
}
p->tot_len = size;
pbuf_refresh();
}
#endif
/**
* Decreases the header size by the given amount.
* Tries to decrease the payload pointer by the given header size.
*
* Adjusts the ->payload pointer so that space for a header appears in
* the pbuf. Also, the ->tot_len and ->len fields are adjusted.
@ -569,14 +481,15 @@ pbuf_realloc(struct pbuf *p, u16_t size)
*
* @return 1 on failure, 0 on succes.
*/
/*-----------------------------------------------------------------------------------*/
u8_t
pbuf_header(struct pbuf *p, s16_t header_size)
{
void *payload;
/* referencing pbufs cannot be realloc()ed */
/* TODO: WHY NOT? just adjust payload, tot_len and len? */
if (p->flags == PBUF_FLAG_ROM ||
p->flags == PBUF_FLAG_REF) {
/* failure */
return 1;
}
@ -603,28 +516,34 @@ pbuf_header(struct pbuf *p, s16_t header_size)
/**
* Free a pbuf (chain) from its user, de-allocate if zero users.
*
* For a single pbuf, decrement its reference count. If it reaches
* zero, de-allocate the associated memory.
* Decrements the pbuf reference count. If it reaches
* zero, the pbuf is deallocated.
*
* For chained pbufs, all reference counts of the pbufs in the chain
* are decremented. Only if the first pbuf reference count reaches
* zero, all pbufs are de-allocated.
* This is repeated for each pbuf in the chain, until a non-zero
* reference count is encountered, or the end of the chain is reached.
*
* @param pbuf pbuf (chain) to be freed from its user.
*
* @note The reference count should not decrease when inspecting the
* pbuf chain from head to tail.
* @return the number of unreferenced pbufs that were de-allocated
* from the head of the chain.
*
* @note Chained pbufs with different reference counts should really
* not occur. Something that references to the first pbuf, has access
* to the complete chain, so all references
* @note the reference counter of a pbuf equals the number of pointers
* that refer to the pbuf (or into the pbuf).
*
* @internal examples:
*
* 1->2->3 becomes ...1->3
* 3->3->3 becomes 2->3->3
* 1->1->2 becomes ....->1
* 2->1->1 becomes 1->1->1
* 1->1->1 becomes .......
*
*/
/*-----------------------------------------------------------------------------------*/
u8_t
pbuf_free(struct pbuf *p)
{
struct pbuf *q;
u8_t count = 0;
u8_t count;
SYS_ARCH_DECL_PROTECT(old_level);
if (p == NULL) {
@ -639,119 +558,109 @@ pbuf_free(struct pbuf *p)
p->flags == PBUF_FLAG_RAM ||
p->flags == PBUF_FLAG_REF );
LWIP_ASSERT("pbuf_free: p->ref > 0", p->ref > 0);
p->ref--;
/* Since decrementing ref cannot be guarranteed to be a single machine operation
q = p;
count = 0;
/* Since decrementing ref cannot be guaranteed to be a single machine operation
* we must protect it. Also, the later test of ref must be protected.
*/
SYS_ARCH_PROTECT(old_level);
/* decrement individual reference count for each pbuf in chain */
for (q = p->next; q != NULL; q = q->next) {
/* reference counts can be 0, as 2nd and further pbufs will
only be freed if the head of the chain is freed */
LWIP_ASSERT("pbuf_free: q->ref >= 0", q->ref >= 0);
/* decrease reference count, but do not wrap! */
if (q->ref > 0)
q->ref--;
}
/* first pbuf now no longer needed? */
if (p->ref == 0) {
SYS_ARCH_UNPROTECT(old_level);
while (p != NULL) {
/* remember next in chain */
/* de-allocate all consecutive pbufs from the head of the chain that
* obtain a zero reference count */
while (p != NULL) {
/* all pbufs in a chain are referenced at least once */
LWIP_ASSERT("pbuf_free: q->ref > 0", q->ref > 0);
p->ref--;
/* this pbuf is no longer referenced to? */
if (p->ref == 0)
{
/* remember next pbuf in chain for next iteration */
q = p->next;
/* this is a pbuf from the pool? */
/* is this a pbuf from the pool? */
if (p->flags == PBUF_FLAG_POOL) {
p->len = p->tot_len = PBUF_POOL_BUFSIZE;
p->payload = (void *)((u8_t *)p + sizeof(struct pbuf));
PBUF_POOL_FREE(p);
/* RAM/ROM referencing pbuf */
/* a RAM/ROM referencing pbuf */
} else if (p->flags == PBUF_FLAG_ROM || p->flags == PBUF_FLAG_REF) {
memp_freep(MEMP_PBUF, p);
/* pbuf with data */
} else {
mem_free(p);
}
/* next in chain */
count++;
/* proceed to next pbuf */
p = q;
/* Only free the next one in a chain if it's reference count is 0.
This allows buffer chains to have multiple headers pointing to them. */
if (p != NULL)
{
p->ref--;
if (p->ref > 0)
break;
}
++count;
/* p->ref > 0, this pbuf is still referenced to */
/* (so the remaining pbufs in chain as well) */
} else {
/* stop walking through chain */
p = NULL;
}
pbuf_refresh();
} else
SYS_ARCH_UNPROTECT(old_level);
}
SYS_ARCH_UNPROTECT(old_level);
pbuf_refresh();
PERF_STOP("pbuf_free");
/* return number of de-allocated pbufs */
return count;
}
/*-----------------------------------------------------------------------------------*/
/* pbuf_clen():
/**
* Count number of pbufs in a chain
*
* Returns the length of the pbuf chain.
* @param p first pbuf of chain
* @return the number of pbufs in a chain
*/
/*-----------------------------------------------------------------------------------*/
u8_t
pbuf_clen(struct pbuf *p)
{
u8_t len;
if(p == NULL) {
return 0;
}
for(len = 0; p != NULL; p = p->next) {
len = 0;
while (p != NULL) {
++len;
p = p->next;
}
return len;
}
/*-----------------------------------------------------------------------------------*/
/* pbuf_ref():
/**
*
* Increment the reference count of the pbuf.
*
* @param p pbuf to increase reference counter of
*
* Increments the reference count of the pbuf.
*/
/*-----------------------------------------------------------------------------------*/
void
pbuf_ref(struct pbuf *p)
{
SYS_ARCH_DECL_PROTECT(old_level);
if(p == NULL) {
return;
SYS_ARCH_DECL_PROTECT(old_level);
/* pbuf given? */
if(p != NULL) {
SYS_ARCH_PROTECT(old_level);
++(p->ref);
SYS_ARCH_UNPROTECT(old_level);
}
SYS_ARCH_PROTECT(old_level);
++(p->ref);
SYS_ARCH_UNPROTECT(old_level);
}
/*------------------------------------------------------------------------------*/
/* pbuf_ref_chain():
/**
*
* Increment the reference count of all pbufs in a chain.
*
* @param p first pbuf of chain
*
* Increments the reference count of all pbufs in a chain.
*/
void
pbuf_ref_chain(struct pbuf *p)
{
SYS_ARCH_DECL_PROTECT(old_level);
SYS_ARCH_PROTECT(old_level);
SYS_ARCH_DECL_PROTECT(old_level);
SYS_ARCH_PROTECT(old_level);
while (p != NULL) {
p->ref++;
p=p->next;
}
SYS_ARCH_UNPROTECT(old_level);
while (p != NULL) {
++p->ref;
p = p->next;
}
SYS_ARCH_UNPROTECT(old_level);
}
@ -761,7 +670,6 @@ pbuf_ref_chain(struct pbuf *p)
*
* The ->tot_len field of the first pbuf (h) is adjusted.
*/
/*-----------------------------------------------------------------------------------*/
void
pbuf_chain(struct pbuf *h, struct pbuf *t)
{
@ -771,17 +679,15 @@ pbuf_chain(struct pbuf *h, struct pbuf *t)
LWIP_ASSERT("t != NULL", t != NULL);
/* proceed to last pbuf of chain */
for(p = h; p->next != NULL; p = p->next) {
for (p = h; p->next != NULL; p = p->next) {
/* add length of second chain to totals of first chain */
p->tot_len += t->tot_len;
}
/* chain */
/* chain last pbuf of h chain (p) with first of tail (t) */
p->next = t;
#if PBUF_CHAIN_DOES_REFER /** TODO (WORK IN PROGRESS) */
/* t is now referenced to one more time */
pbuf_ref(t);
DEBUGF(PBUF_DEBUG | DBG_FRESH | 2, ("pbuf_chain: referencing %p\n", (void *) t));
#endif
DEBUGF(PBUF_DEBUG | DBG_FRESH | 2, ("pbuf_chain: referencing tail %p\n", (void *) t));
}
/**
@ -789,13 +695,13 @@ pbuf_chain(struct pbuf *h, struct pbuf *t)
*
* Makes p->tot_len field equal to p->len.
* @param p pbuf to dechain
* @return remainder (if any) of the pbuf chain.
* @return remainder of the pbuf chain, or NULL if it was de-allocated.
*/
struct pbuf *
pbuf_dechain(struct pbuf *p)
{
struct pbuf *q;
/* tail */
q = p->next;
/* pbuf has successor in chain? */
if (q != NULL) {
@ -809,10 +715,11 @@ pbuf_dechain(struct pbuf *p)
p->next = NULL;
#if PBUF_CHAIN_DOES_REFER /** TODO (WORK IN PROGRESS) */
/* q is no longer referenced by p */
pbuf_free(q);
deallocated = pbuf_free(q);
DEBUGF(PBUF_DEBUG | DBG_FRESH | 2, ("pbuf_dechain: unreferencing %p\n", (void *) q));
#endif
return q;
/* return remaining tail or NULL if deallocated */
return (deallocated? NULL: q);
}
/**
@ -823,19 +730,25 @@ pbuf_dechain(struct pbuf *p)
* with PBUF_POOL (or PBUF_RAM) pbufs, each taking a copy of
* the referenced data.
*
* Used to queue packets on behalf of the lwIP stack, such as ARP based
* queueing.
* @note The pbuf you give as argument, may have been replaced
* by calling pbuf_take(p). You must therefore explicitly use
* p = pbuf_take(p);
* @note Any replaced pbufs will be freed through pbuf_free().
*
* Used to queue packets on behalf of the lwIP stack, such as
* ARP based queueing.
*
* @param f Head of pbuf chain to process
*
* @return Pointer to new head of pbuf chain.
* @return Pointer to new head of pbuf chain (which may have been
* replaced itself).
*/
struct pbuf *
pbuf_take(struct pbuf *f)
{
struct pbuf *p, *prev, *top;
LWIP_ASSERT("pbuf_take: f != NULL", f != NULL);
DEBUGF(PBUF_DEBUG | DBG_TRACE | 3, ("pbuf_take(%p)\n", (void*)f));
DEBUGF(PBUF_DEBUG | DBG_TRACE | 3, ("pbuf_take(%p)", (void*)f));
prev = NULL;
p = f;
@ -848,29 +761,44 @@ pbuf_take(struct pbuf *f)
{
/* the replacement pbuf */
struct pbuf *q;
q = NULL;
DEBUGF(PBUF_DEBUG | DBG_TRACE, ("pbuf_take: encountered PBUF_REF %p\n", (void *)p));
DEBUGF(PBUF_DEBUG | DBG_TRACE, ("pbuf_take: encountered PBUF_REF %p", (void *)p));
/* allocate a pbuf (w/ payload) fully in RAM */
/* PBUF_POOL buffers are faster if we can use them */
if (p->len <= PBUF_POOL_BUFSIZE) {
q = pbuf_alloc(PBUF_RAW, p->len, PBUF_POOL);
if (q == NULL) DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_take: Could not allocate PBUF_RAW\n"));
if (q == NULL) DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_take: Could not allocate PBUF_POOL"));
} else {
/* no replacement pbuf yet */
q = NULL;
DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_take: PBUF_POOL too small to replace PBUF_REF"));
}
/* no (large enough) PBUF_POOL was available? retry with PBUF_RAM */
if (q == NULL) {
q = pbuf_alloc(PBUF_RAW, p->len, PBUF_RAM);
if (q == NULL) DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_take: Could not allocate PBUF_POOL\n"));
if (q == NULL) DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_take: Could not allocate PBUF_RAM"));
}
/* replacement pbuf could be allocated? */
if (q != NULL)
{
/* copy successor */
q->next = p->next;
/* remove linkage from original pbuf */
p->next = NULL;
/* remove linkage to original pbuf */
if (prev != NULL)
/* Break chain and insert new pbuf instead */
/* prev->next == p at this point */
/* break chain and insert new pbuf instead */
prev->next = q;
/* p is no longer pointed to by prev or by our caller,
* as the caller must do p = pbuf_take(p); so free it
* from our usage.
* note that we have set p->next to NULL already so that
* we will not free the rest of the chain by accident.
*/
pbuf_free(p);
/* prev == NULL, so we replaced the top pbuf of the chain */
else
top = q;
p->next = NULL;
/* copy pbuf payload */
memcpy(q->payload, p->payload, p->len);
q->tot_len = p->tot_len;

10
src/include/lwip/pbuf.h
View File

@ -74,8 +74,14 @@ struct pbuf {
/* Length of this buffer. */
u16_t len;
/* Flags and reference count. */
u16_t flags, ref;
/* flags */
u16_t flags;
/** the reference count always equals the number of pointers
* that refer to this pbuf. This can be pointers from an application,
* the stack itself, or pbuf->next pointers from a chain.
*/
u16_t ref;
};