netfilter: {ip,ip6,nfnetlink}_queue: misc cleanups

- No need to perform data_len = 0 in the switch command, since data_len
  is initialized to 0 in the beginning of the ipq_build_packet_message()
  method.

- {ip,ip6}_queue: We can reach nlmsg_failure only from one place; skb is
  sure to be NULL when getting there; since skb is NULL, there is no need
  to check this fact and call kfree_skb().

Signed-off-by: Rami Rosen <ramirose@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/netfilter/ip_queue.c

@@ -156,7 +156,6 @@ ipq_build_packet_message(struct nf_queue_entry *entry, int *errp)
 	case IPQ_COPY_META:
 	case IPQ_COPY_NONE:
 		size = NLMSG_SPACE(sizeof(*pmsg));
-		data_len = 0;
 		break;
 
 	case IPQ_COPY_PACKET:
@@ -224,8 +223,6 @@ ipq_build_packet_message(struct nf_queue_entry *entry, int *errp)
 	return skb;
 
 nlmsg_failure:
-	if (skb)
-		kfree_skb(skb);
 	*errp = -EINVAL;
 	printk(KERN_ERR "ip_queue: error creating packet message\n");
 	return NULL;

net/ipv6/netfilter/ip6_queue.c

@@ -159,7 +159,6 @@ ipq_build_packet_message(struct nf_queue_entry *entry, int *errp)
 	case IPQ_COPY_META:
 	case IPQ_COPY_NONE:
 		size = NLMSG_SPACE(sizeof(*pmsg));
-		data_len = 0;
 		break;
 
 	case IPQ_COPY_PACKET:
@@ -226,8 +225,6 @@ ipq_build_packet_message(struct nf_queue_entry *entry, int *errp)
 	return skb;
 
 nlmsg_failure:
-	if (skb)
-		kfree_skb(skb);
 	*errp = -EINVAL;
 	printk(KERN_ERR "ip6_queue: error creating packet message\n");
 	return NULL;

net/netfilter/nfnetlink_queue.c

@@ -243,7 +243,6 @@ nfqnl_build_packet_message(struct nfqnl_instance *queue,
 	switch ((enum nfqnl_config_mode)queue->copy_mode) {
 	case NFQNL_COPY_META:
 	case NFQNL_COPY_NONE:
-		data_len = 0;
 		break;
 
 	case NFQNL_COPY_PACKET: