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 <bro...@redhat.com>
---
include/linux/skbuff.h | 2 +
net/core/skbuff.c | 71 +++++++++++++++++++++++++++++++++++-------------
2 files changed, 54 insertions(+), 19 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 9027a8c4219f..c40ffab8a9b0 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1044,6 +1044,8 @@ 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
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 4782f9354dd1..d904b6e5fe08 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -258,6 +258,33 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t
gfp_mask,
}
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 {
