ipmr: __pim_rcv() is called under rcu_read_lock

No need to get a reference on reg_dev and release it, we are in a
rcu_read_lock() protected section.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/ipmr.c

@@ -1805,6 +1805,7 @@ int ip_mr_input(struct sk_buff *skb)
 }
 
 #ifdef CONFIG_IP_PIMSM
+/* called with rcu_read_lock() */
 static int __pim_rcv(struct mr_table *mrt, struct sk_buff *skb,
 		     unsigned int pimlen)
 {
@@ -1826,26 +1827,23 @@ static int __pim_rcv(struct mr_table *mrt, struct sk_buff *skb,
 	read_lock(&mrt_lock);
 	if (mrt->mroute_reg_vif_num >= 0)
 		reg_dev = mrt->vif_table[mrt->mroute_reg_vif_num].dev;
-	if (reg_dev)
-		dev_hold(reg_dev);
 	read_unlock(&mrt_lock);
 
 	if (reg_dev == NULL)
 		return 1;
 
 	skb->mac_header = skb->network_header;
-	skb_pull(skb, (u8*)encap - skb->data);
+	skb_pull(skb, (u8 *)encap - skb->data);
 	skb_reset_network_header(skb);
 	skb->protocol = htons(ETH_P_IP);
-	skb->ip_summed = 0;
+	skb->ip_summed = CHECKSUM_NONE;
 	skb->pkt_type = PACKET_HOST;
 
 	skb_tunnel_rx(skb, reg_dev);
 
 	netif_rx(skb);
-	dev_put(reg_dev);
 
-	return 0;
+	return NET_RX_SUCCESS;
 }
 #endif