net: ipv6: add skb drop reasons to ip6_pkt_drop()

Replace kfree_skb() used in ip6_pkt_drop() with kfree_skb_reason().
No new reason is added.
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/route.c

@@ -4482,6 +4482,7 @@ static int ip6_pkt_drop(struct sk_buff *skb, u8 code, int ipstats_mib_noroutes)
 	struct dst_entry *dst = skb_dst(skb);
 	struct net *net = dev_net(dst->dev);
 	struct inet6_dev *idev;
+	SKB_DR(reason);
 	int type;
 
 	if (netif_is_l3_master(skb->dev) ||
@@ -4494,11 +4495,14 @@ static int ip6_pkt_drop(struct sk_buff *skb, u8 code, int ipstats_mib_noroutes)
 	case IPSTATS_MIB_INNOROUTES:
 		type = ipv6_addr_type(&ipv6_hdr(skb)->daddr);
 		if (type == IPV6_ADDR_ANY) {
+			SKB_DR_SET(reason, IP_INADDRERRORS);
 			IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
 			break;
 		}
+		SKB_DR_SET(reason, IP_INNOROUTES);
 		fallthrough;
 	case IPSTATS_MIB_OUTNOROUTES:
+		SKB_DR_OR(reason, IP_OUTNOROUTES);
 		IP6_INC_STATS(net, idev, ipstats_mib_noroutes);
 		break;
 	}
@@ -4508,7 +4512,7 @@ static int ip6_pkt_drop(struct sk_buff *skb, u8 code, int ipstats_mib_noroutes)
 		skb_dst_drop(skb);
 
 	icmpv6_send(skb, ICMPV6_DEST_UNREACH, code, 0);
-	kfree_skb(skb);
+	kfree_skb_reason(skb, reason);
 	return 0;
 }