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net: buf: keep memory alignment provided by k_heap_alloc and k_malloc

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Allocation callback in net_buf_heap_cb and net_buf_var_cb
used for net_bufs with variable size payloads, defined by
NET_BUF_POOL_HEAP_DEFINE or NET_BUF_POOL_VAR_DEFINE,
allocate one more octet for internal variable ref_count,
used in function generic_data_ref(), which in turn is needed
for net_buf_clone()).
The user gets a buffer which is shifted by one octet in memory
block. This breaks alignment provided k_heap_alloc and k_malloc.

Signed-off-by: Johann Fischer <johann.fischer@nordicsemi.no>
This commit is contained in:
Johann Fischer 2022-05-16 14:47:56 +02:00 • committed by Carles Cufí
commit b70f92e570
1 changed files with 6 additions and 6 deletions
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12
subsys/net/buf.c
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@ -107,7 +107,7 @@ static uint8_t *mem_pool_data_alloc(struct net_buf *buf, size_t *size,
uint8_t *ref_count; uint8_t *ref_count;
/* Reserve extra space for a ref-count (uint8_t) */ /* Reserve extra space for a ref-count (uint8_t) */
void *b = k_heap_alloc(pool, 1 + *size, timeout); void *b = k_heap_alloc(pool, sizeof(void *) + *size, timeout);
if (b == NULL) { if (b == NULL) {
return NULL; return NULL;
@ -117,7 +117,7 @@ static uint8_t *mem_pool_data_alloc(struct net_buf *buf, size_t *size,
*ref_count = 1U; *ref_count = 1U;
/* Return pointer to the byte following the ref count */ /* Return pointer to the byte following the ref count */
return ref_count + 1; return ref_count + sizeof(void *);
} }
static void mem_pool_data_unref(struct net_buf *buf, uint8_t *data) static void mem_pool_data_unref(struct net_buf *buf, uint8_t *data)
@ -126,7 +126,7 @@ static void mem_pool_data_unref(struct net_buf *buf, uint8_t *data)
struct k_heap *pool = buf_pool->alloc->alloc_data; struct k_heap *pool = buf_pool->alloc->alloc_data;
uint8_t *ref_count; uint8_t *ref_count;
ref_count = data - 1; ref_count = data - sizeof(void *);
if (--(*ref_count)) { if (--(*ref_count)) {
return; return;
} }
@ -169,21 +169,21 @@ static uint8_t *heap_data_alloc(struct net_buf *buf, size_t *size,
{ {
uint8_t *ref_count; uint8_t *ref_count;
ref_count = k_malloc(1 + *size); ref_count = k_malloc(sizeof(void *) + *size);
if (!ref_count) { if (!ref_count) {
return NULL; return NULL;
} }
*ref_count = 1U; *ref_count = 1U;
return ref_count + 1; return ref_count + sizeof(void *);
} }
static void heap_data_unref(struct net_buf *buf, uint8_t *data) static void heap_data_unref(struct net_buf *buf, uint8_t *data)
{ {
uint8_t *ref_count; uint8_t *ref_count;
ref_count = data - 1; ref_count = data - sizeof(void *);
if (--(*ref_count)) { if (--(*ref_count)) {
return; return;
} }