packet: uses kfree_skb() for errors.

consume_skb() isn't for error cases that kfree_skb() is more proper
one.  At this patch, it fixed tpacket_rcv() and packet_rcv() to be
consistent for error or non-error cases letting perf trace its event
properly.
Signed-off-by: Weongyo Jeong <weongyo.linux@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/packet/af_packet.c

@@ -2052,6 +2052,7 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev,
 	u8 *skb_head = skb->data;
 	int skb_len = skb->len;
 	unsigned int snaplen, res;
+	bool is_drop_n_account = false;
 
 	if (skb->pkt_type == PACKET_LOOPBACK)
 		goto drop;
@@ -2140,6 +2141,7 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev,
 	return 0;
 
 drop_n_acct:
+	is_drop_n_account = true;
 	spin_lock(&sk->sk_receive_queue.lock);
 	po->stats.stats1.tp_drops++;
 	atomic_inc(&sk->sk_drops);
@@ -2151,7 +2153,10 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev,
 		skb->len = skb_len;
 	}
 drop:
-	consume_skb(skb);
+	if (!is_drop_n_account)
+		consume_skb(skb);
+	else
+		kfree_skb(skb);
 	return 0;
 }
 
@@ -2170,6 +2175,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
 	struct sk_buff *copy_skb = NULL;
 	struct timespec ts;
 	__u32 ts_status;
+	bool is_drop_n_account = false;
 
 	/* struct tpacket{2,3}_hdr is aligned to a multiple of TPACKET_ALIGNMENT.
 	 * We may add members to them until current aligned size without forcing
@@ -2377,10 +2383,14 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
 		skb->len = skb_len;
 	}
 drop:
-	kfree_skb(skb);
+	if (!is_drop_n_account)
+		consume_skb(skb);
+	else
+		kfree_skb(skb);
 	return 0;
 
 drop_n_account:
+	is_drop_n_account = true;
 	po->stats.stats1.tp_drops++;
 	spin_unlock(&sk->sk_receive_queue.lock);