net: icmp: introduce __ping_queue_rcv_skb() to report drop reasons

In order to avoid to change the return value of ping_queue_rcv_skb(),
introduce the function __ping_queue_rcv_skb(), which is able to report
the reasons of skb drop as its return value, as Paolo suggested.

Meanwhile, make ping_queue_rcv_skb() a simple call to
__ping_queue_rcv_skb().

The kfree_skb() and sock_queue_rcv_skb() used in ping_queue_rcv_skb()
are replaced with kfree_skb_reason() and sock_queue_rcv_skb_reason()
now.
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/ping.c

@@ -935,16 +935,24 @@ int ping_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
 }
 EXPORT_SYMBOL_GPL(ping_recvmsg);
 
-int ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
+static enum skb_drop_reason __ping_queue_rcv_skb(struct sock *sk,
+						 struct sk_buff *skb)
 {
+	enum skb_drop_reason reason;
+
 	pr_debug("ping_queue_rcv_skb(sk=%p,sk->num=%d,skb=%p)\n",
 		 inet_sk(sk), inet_sk(sk)->inet_num, skb);
-	if (sock_queue_rcv_skb(sk, skb) < 0) {
-		kfree_skb(skb);
+	if (sock_queue_rcv_skb_reason(sk, skb, &reason) < 0) {
+		kfree_skb_reason(skb, reason);
 		pr_debug("ping_queue_rcv_skb -> failed\n");
-		return -1;
+		return reason;
 	}
-	return 0;
+	return SKB_NOT_DROPPED_YET;
+}
+
+int ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
+{
+	return __ping_queue_rcv_skb(sk, skb) ? -1 : 0;
 }
 EXPORT_SYMBOL_GPL(ping_queue_rcv_skb);