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net: core: introduce build_skb_around 

The function build_skb() also have the responsibility to allocate and clear
the SKB structure. Introduce a new function build_skb_around(), that moves
the responsibility of allocation and clearing to the caller. This allows
caller to use kmem_cache (slab/slub) bulk allocation API.

Next patch use this function combined with kmem_cache_alloc_bulk.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Jesper Dangaard Brouer 2019-04-12 17:07:37 +02:00 committed by Alexei Starovoitov
parent 77361825bb
commit ba0509b688
2 changed files with 54 additions and 19 deletions
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2
include/linux/skbuff.h
View File

@ -1042,6 +1042,8 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t priority, int flags,
int node);
struct sk_buff *__build_skb(void *data, unsigned int frag_size);
struct sk_buff *build_skb(void *data, unsigned int frag_size);
struct sk_buff *build_skb_around(struct sk_buff *skb,
void *data, unsigned int frag_size);
/**
* alloc_skb - allocate a network buffer

71
net/core/skbuff.c
View File

@ -258,6 +258,33 @@ nodata:
}
EXPORT_SYMBOL(__alloc_skb);
/* Caller must provide SKB that is memset cleared */
static struct sk_buff *__build_skb_around(struct sk_buff *skb,
void *data, unsigned int frag_size)
{
struct skb_shared_info *shinfo;
unsigned int size = frag_size ? : ksize(data);
size -= SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
/* Assumes caller memset cleared SKB */
skb->truesize = SKB_TRUESIZE(size);
refcount_set(&skb->users, 1);
skb->head = data;
skb->data = data;
skb_reset_tail_pointer(skb);
skb->end = skb->tail + size;
skb->mac_header = (typeof(skb->mac_header))~0U;
skb->transport_header = (typeof(skb->transport_header))~0U;
/* make sure we initialize shinfo sequentially */
shinfo = skb_shinfo(skb);
memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
atomic_set(&shinfo->dataref, 1);
return skb;
}
/**
* __build_skb - build a network buffer
* @data: data buffer provided by caller
@ -279,32 +306,15 @@ EXPORT_SYMBOL(__alloc_skb);
*/
struct sk_buff *__build_skb(void *data, unsigned int frag_size)
{
struct skb_shared_info *shinfo;
struct sk_buff *skb;
unsigned int size = frag_size ? : ksize(data);
skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
if (!skb)
if (unlikely(!skb))
return NULL;
size -= SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
memset(skb, 0, offsetof(struct sk_buff, tail));
skb->truesize = SKB_TRUESIZE(size);
refcount_set(&skb->users, 1);
skb->head = data;
skb->data = data;
skb_reset_tail_pointer(skb);
skb->end = skb->tail + size;
skb->mac_header = (typeof(skb->mac_header))~0U;
skb->transport_header = (typeof(skb->transport_header))~0U;
/* make sure we initialize shinfo sequentially */
shinfo = skb_shinfo(skb);
memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
atomic_set(&shinfo->dataref, 1);
return skb;
return __build_skb_around(skb, data, frag_size);
}
/* build_skb() is wrapper over __build_skb(), that specifically
@ -325,6 +335,29 @@ struct sk_buff *build_skb(void *data, unsigned int frag_size)
}
EXPORT_SYMBOL(build_skb);
/**
* build_skb_around - build a network buffer around provided skb
* @skb: sk_buff provide by caller, must be memset cleared
* @data: data buffer provided by caller
* @frag_size: size of data, or 0 if head was kmalloced
*/
struct sk_buff *build_skb_around(struct sk_buff *skb,
void *data, unsigned int frag_size)
{
if (unlikely(!skb))
return NULL;
skb = __build_skb_around(skb, data, frag_size);
if (skb && frag_size) {
skb->head_frag = 1;
if (page_is_pfmemalloc(virt_to_head_page(data)))
skb->pfmemalloc = 1;
}
return skb;
}
EXPORT_SYMBOL(build_skb_around);
#define NAPI_SKB_CACHE_SIZE 64
struct napi_alloc_cache {