udp: remove headers from UDP packets before queueing

Remove UDP transport headers before queueing packets for reception.
This change simplifies a follow-up patch to add MSG_PEEK support.

Signed-off-by: Sam Kumar <samanthakumar@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/sock.c b/net/core/sock.c
index 2f517ea..e12197b 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -402,9 +402,8 @@
 }
 
 
-int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
+int __sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 {
-	int err;
 	unsigned long flags;
 	struct sk_buff_head *list = &sk->sk_receive_queue;
 
@@ -414,10 +413,6 @@
 		return -ENOMEM;
 	}
 
-	err = sk_filter(sk, skb);
-	if (err)
-		return err;
-
 	if (!sk_rmem_schedule(sk, skb, skb->truesize)) {
 		atomic_inc(&sk->sk_drops);
 		return -ENOBUFS;
@@ -440,6 +435,18 @@
 		sk->sk_data_ready(sk);
 	return 0;
 }
+EXPORT_SYMBOL(__sock_queue_rcv_skb);
+
+int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
+{
+	int err;
+
+	err = sk_filter(sk, skb);
+	if (err)
+		return err;
+
+	return __sock_queue_rcv_skb(sk, skb);
+}
 EXPORT_SYMBOL(sock_queue_rcv_skb);
 
 int sk_receive_skb(struct sock *sk, struct sk_buff *skb, const int nested)