Commit ba0509b6 authored by Jesper Dangaard Brouer's avatar Jesper Dangaard Brouer Committed by Alexei Starovoitov
Browse files

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: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 77361825

include/linux/skbuff.h

+2 −0
Original line number Diff line number Diff line
@@ -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

net/core/skbuff.c

+52 −19
Original line number Diff line number Diff line
@@ -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 {

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