From abc24ef7a69f54c3317beea98078831ba9bfa2cd Mon Sep 17 00:00:00 2001
From: Madalin Bucur <madalin.bucur@freescale.com>
Date: Tue, 5 Jan 2016 12:12:07 +0200
Subject: [PATCH 19/70] net: readd skb_recycle()

Adding back skb_recycle() as it's used by the DPAA Ethernet driver.
This was removed from the upstream kernel because it was lacking users.

Signed-off-by: Madalin Bucur <madalin.bucur@freescale.com>
---
 include/linux/skbuff.h |    1 +
 net/core/skbuff.c      |   26 ++++++++++++++++++++++++++
 2 files changed, 27 insertions(+)

--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -799,6 +799,7 @@ void kfree_skb(struct sk_buff *skb);
 void kfree_skb_list(struct sk_buff *segs);
 void skb_tx_error(struct sk_buff *skb);
 void consume_skb(struct sk_buff *skb);
+void skb_recycle(struct sk_buff *skb);
 void  __kfree_skb(struct sk_buff *skb);
 extern struct kmem_cache *skbuff_head_cache;
 
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -766,6 +766,32 @@ 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;
+	u8 head_frag = skb->head_frag;
+
+	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->head_frag = head_frag;
+	skb_reset_tail_pointer(skb);
+}
+EXPORT_SYMBOL(skb_recycle);
+
 /* Make sure a field is enclosed inside headers_start/headers_end section */
 #define CHECK_SKB_FIELD(field) \
 	BUILD_BUG_ON(offsetof(struct sk_buff, field) <		\
