skbuff: fix ftrace handling in skb_unshare

If the skb is not dropped afterwards we should run consume_skb instead
kfree_skb. Inside of function skb_unshare we do always a kfree_skb,
doesn't depend if skb_copy failed or was successful.

This patch switch this behaviour like skb_share_check, if allocation of
sk_buff failed we use kfree_skb otherwise consume_skb.
Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/skbuff.h

@@ -1203,7 +1203,12 @@ static inline struct sk_buff *skb_unshare(struct sk_buff *skb,
 	might_sleep_if(pri & __GFP_WAIT);
 	if (skb_cloned(skb)) {
 		struct sk_buff *nskb = skb_copy(skb, pri);
-		kfree_skb(skb);	/* Free our shared copy */
+
+		/* Free our shared copy */
+		if (likely(nskb))
+			consume_skb(skb);
+		else
+			kfree_skb(skb);
 		skb = nskb;
 	}
 	return skb;