netfilter: nat: remove unnecessary rcu_read_lock in nf_nat_redirect_ipv{4/6}

nf_nat_redirect_ipv4() and nf_nat_redirect_ipv6() are only called by
netfilter hook point. so that rcu_read_lock and rcu_read_unlock() are
unnecessary.
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_nat_redirect.c

@@ -52,13 +52,11 @@ nf_nat_redirect_ipv4(struct sk_buff *skb,
 
 		newdst = 0;
 
-		rcu_read_lock();
 		indev = __in_dev_get_rcu(skb->dev);
 		if (indev && indev->ifa_list) {
 			ifa = indev->ifa_list;
 			newdst = ifa->ifa_local;
 		}
-		rcu_read_unlock();
 
 		if (!newdst)
 			return NF_DROP;
@@ -97,7 +95,6 @@ nf_nat_redirect_ipv6(struct sk_buff *skb, const struct nf_nat_range2 *range,
 		struct inet6_ifaddr *ifa;
 		bool addr = false;
 
-		rcu_read_lock();
 		idev = __in6_dev_get(skb->dev);
 		if (idev != NULL) {
 			read_lock_bh(&idev->lock);
@@ -108,7 +105,6 @@ nf_nat_redirect_ipv6(struct sk_buff *skb, const struct nf_nat_range2 *range,
 			}
 			read_unlock_bh(&idev->lock);
 		}
-		rcu_read_unlock();
 
 		if (!addr)
 			return NF_DROP;