Commit 0ebd0ac5 authored by Patrick McHardy's avatar Patrick McHardy Committed by David S. Miller

net: add function to allocate sk_buff head without data area

Add a function to allocate a sk_buff head without any data. This will
be used by memory mapped netlink to attach data from the mmaped area
to the skb.

Additionally change skb_release_all() to check whether the skb has a
data area to allow the skb destructor to clear the data pointer in case
only a head has been allocated.
Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e32123e5
......@@ -651,6 +651,12 @@ static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
}
extern struct sk_buff *__alloc_skb_head(gfp_t priority, int node);
static inline struct sk_buff *alloc_skb_head(gfp_t priority)
{
return __alloc_skb_head(priority, -1);
}
extern struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
extern int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask);
extern struct sk_buff *skb_clone(struct sk_buff *skb,
......
......@@ -179,6 +179,33 @@ static void *__kmalloc_reserve(size_t size, gfp_t flags, int node,
*
*/
struct sk_buff *__alloc_skb_head(gfp_t gfp_mask, int node)
{
struct sk_buff *skb;
/* Get the HEAD */
skb = kmem_cache_alloc_node(skbuff_head_cache,
gfp_mask & ~__GFP_DMA, node);
if (!skb)
goto out;
/*
* Only clear those fields we need to clear, not those that we will
* actually initialise below. Hence, don't put any more fields after
* the tail pointer in struct sk_buff!
*/
memset(skb, 0, offsetof(struct sk_buff, tail));
skb->data = NULL;
skb->truesize = sizeof(struct sk_buff);
atomic_set(&skb->users, 1);
#ifdef NET_SKBUFF_DATA_USES_OFFSET
skb->mac_header = ~0U;
#endif
out:
return skb;
}
/**
* __alloc_skb - allocate a network buffer
* @size: size to allocate
......@@ -584,6 +611,7 @@ static void skb_release_head_state(struct sk_buff *skb)
static void skb_release_all(struct sk_buff *skb)
{
skb_release_head_state(skb);
if (likely(skb->data))
skb_release_data(skb);
}
......
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