2 files changed, 71 insertions, 0 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 320e976..e401875 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -602,6 +602,9 @@ static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
 	return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
 }
 
+extern void skb_recycle(struct sk_buff *skb);
+extern bool skb_recycle_check(struct sk_buff *skb, int skb_size);
+
 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,
@@ -2738,6 +2741,27 @@ static inline void skb_checksum_none_assert(const struct sk_buff *skb)
 
 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
 
+static inline bool skb_is_recycleable(const struct sk_buff *skb, int skb_size)
+{
+	if (irqs_disabled())
+		return false;
+
+	if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)
+		return false;
+
+	if (skb_is_nonlinear(skb) || skb->fclone != SKB_FCLONE_UNAVAILABLE)
+		return false;
+
+	skb_size = SKB_DATA_ALIGN(skb_size + NET_SKB_PAD);
+	if (skb_end_offset(skb) < skb_size)
+		return false;
+
+	if (skb_shared(skb) || skb_cloned(skb))
+		return false;
+
+	return true;
+}
+
 /**
  * skb_head_is_locked - Determine if the skb->head is locked down
  * @skb: skb to check
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 32443eb..f4a73cb 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -675,6 +675,53 @@ void consume_skb(struct sk_buff *skb)
 }
 EXPORT_SYMBOL(consume_skb);
 
+/**
+ * 	skb_recycle - clean up an skb for reuse
+ * 	@skb: buffer
+ *
+ * 	Recycles the skb to be reused as a receive buffer. This
+ * 	function does any necessary reference count dropping, and
+ * 	cleans up the skbuff as if it just came from __alloc_skb().
+ */
+void skb_recycle(struct sk_buff *skb)
+{
+	struct skb_shared_info *shinfo;
+
+	skb_release_head_state(skb);
+
+	shinfo = skb_shinfo(skb);
+	memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
+	atomic_set(&shinfo->dataref, 1);
+
+	memset(skb, 0, offsetof(struct sk_buff, tail));
+	skb->data = skb->head + NET_SKB_PAD;
+	skb_reset_tail_pointer(skb);
+}
+EXPORT_SYMBOL(skb_recycle);
+
+/**
+ *	skb_recycle_check - check if skb can be reused for receive
+ *	@skb: buffer
+ *	@skb_size: minimum receive buffer size
+ *
+ *	Checks that the skb passed in is not shared or cloned, and
+ *	that it is linear and its head portion at least as large as
+ *	skb_size so that it can be recycled as a receive buffer.
+ *	If these conditions are met, this function does any necessary
+ *	reference count dropping and cleans up the skbuff as if it
+ *	just came from __alloc_skb().
+ */
+bool skb_recycle_check(struct sk_buff *skb, int skb_size)
+{
+	if (!skb_is_recycleable(skb, skb_size))
+		return false;
+
+	skb_recycle(skb);
+
+	return true;
+}
+EXPORT_SYMBOL(skb_recycle_check);
+
 static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 {
 	new->tstamp		= old->tstamp;