net: ipv4: add skb drop reasons to ip_error()

Eventually, I find out the handler function for inputting route lookup
fail: ip_error().

The drop reasons we used in ip_error() are almost corresponding to
IPSTATS_MIB_*, and following new reasons are introduced:

SKB_DROP_REASON_IP_INADDRERRORS
SKB_DROP_REASON_IP_INNOROUTES

Isn't the name SKB_DROP_REASON_IP_HOSTUNREACH and
SKB_DROP_REASON_IP_NETUNREACH more accurate? To make them corresponding
to IPSTATS_MIB_*, we keep their name still.

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>

include/linux/skbuff.h

@@ -447,6 +447,12 @@ enum skb_drop_reason {
 					 * 2211, such as a broadcasts
 					 * ICMP_TIMESTAMP
 					 */
+	SKB_DROP_REASON_IP_INADDRERRORS,	/* host unreachable, corresponding
+						 * to IPSTATS_MIB_INADDRERRORS
+						 */
+	SKB_DROP_REASON_IP_INNOROUTES,	/* network unreachable, corresponding
+					 * to IPSTATS_MIB_INADDRERRORS
+					 */
 	SKB_DROP_REASON_MAX,
 };
 

include/trace/events/skb.h

@@ -63,6 +63,8 @@
 	EM(SKB_DROP_REASON_TAP_TXFILTER, TAP_TXFILTER)		\
 	EM(SKB_DROP_REASON_ICMP_CSUM, ICMP_CSUM)		\
 	EM(SKB_DROP_REASON_INVALID_PROTO, INVALID_PROTO)	\
+	EM(SKB_DROP_REASON_IP_INADDRERRORS, IP_INADDRERRORS)	\
+	EM(SKB_DROP_REASON_IP_INNOROUTES, IP_INNOROUTES)	\
 	EMe(SKB_DROP_REASON_MAX, MAX)
 
 #undef EM

net/ipv4/route.c

@@ -945,6 +945,7 @@ static int ip_error(struct sk_buff *skb)
 	struct inet_peer *peer;
 	unsigned long now;
 	struct net *net;
+	SKB_DR(reason);
 	bool send;
 	int code;
 
@@ -964,10 +965,12 @@ static int ip_error(struct sk_buff *skb)
 	if (!IN_DEV_FORWARD(in_dev)) {
 		switch (rt->dst.error) {
 		case EHOSTUNREACH:
+			SKB_DR_SET(reason, IP_INADDRERRORS);
 			__IP_INC_STATS(net, IPSTATS_MIB_INADDRERRORS);
 			break;
 
 		case ENETUNREACH:
+			SKB_DR_SET(reason, IP_INNOROUTES);
 			__IP_INC_STATS(net, IPSTATS_MIB_INNOROUTES);
 			break;
 		}
@@ -983,6 +986,7 @@ static int ip_error(struct sk_buff *skb)
 		break;
 	case ENETUNREACH:
 		code = ICMP_NET_UNREACH;
+		SKB_DR_SET(reason, IP_INNOROUTES);
 		__IP_INC_STATS(net, IPSTATS_MIB_INNOROUTES);
 		break;
 	case EACCES:
@@ -1009,7 +1013,7 @@ static int ip_error(struct sk_buff *skb)
 	if (send)
 		icmp_send(skb, ICMP_DEST_UNREACH, code, 0);
 
-out:	kfree_skb(skb);
+out:	kfree_skb_reason(skb, reason);
 	return 0;
 }