net: Add __sock_queue_rcv_skb()

Extraxcted from commit e6afc8ac
"udp: remove headers from UDP packets before queueing".
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

include/net/sock.h

@@ -1629,6 +1629,7 @@ extern void sk_reset_timer(struct sock *sk, struct timer_list* timer,
 
 extern void sk_stop_timer(struct sock *sk, struct timer_list* timer);
 
+int __sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
 extern int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
 
 extern int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb);

net/core/sock.c

@@ -281,9 +281,8 @@ static void sock_disable_timestamp(struct sock *sk, int flag)
 }
 
 
-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;
 	int skb_len;
 	unsigned long flags;
 	struct sk_buff_head *list = &sk->sk_receive_queue;
@@ -294,10 +293,6 @@ int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 		return -ENOMEM;
 	}
 
-	err = sk_filter(sk, skb);
-	if (err)
-		return err;
-
 	if (!sk_rmem_schedule(sk, skb->truesize)) {
 		atomic_inc(&sk->sk_drops);
 		return -ENOBUFS;
@@ -327,6 +322,18 @@ int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 		sk->sk_data_ready(sk, skb_len);
 	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)