ipv4: Remove redundant RCU locking in ip_check_mc().

All callers are under rcu_read_lock() protection already.

Rename to ip_check_mc_rcu() to make it even more clear.
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/igmp.h

@@ -217,7 +217,7 @@ struct ip_mc_list {
 #define IGMPV3_QQIC(value) IGMPV3_EXP(0x80, 4, 3, value)
 #define IGMPV3_MRC(value) IGMPV3_EXP(0x80, 4, 3, value)
 
-extern int ip_check_mc(struct in_device *dev, __be32 mc_addr, __be32 src_addr, u16 proto);
+extern int ip_check_mc_rcu(struct in_device *dev, __be32 mc_addr, __be32 src_addr, u16 proto);
 extern int igmp_rcv(struct sk_buff *);
 extern int ip_mc_join_group(struct sock *sk, struct ip_mreqn *imr);
 extern int ip_mc_leave_group(struct sock *sk, struct ip_mreqn *imr);

net/ipv4/igmp.c

@@ -2333,13 +2333,13 @@ void ip_mc_drop_socket(struct sock *sk)
 	rtnl_unlock();
 }
 
-int ip_check_mc(struct in_device *in_dev, __be32 mc_addr, __be32 src_addr, u16 proto)
+/* called with rcu_read_lock() */
+int ip_check_mc_rcu(struct in_device *in_dev, __be32 mc_addr, __be32 src_addr, u16 proto)
 {
 	struct ip_mc_list *im;
 	struct ip_sf_list *psf;
 	int rv = 0;
 
-	rcu_read_lock();
 	for_each_pmc_rcu(in_dev, im) {
 		if (im->multiaddr == mc_addr)
 			break;
@@ -2361,7 +2361,6 @@ int ip_check_mc(struct in_device *in_dev, __be32 mc_addr, __be32 src_addr, u16 p
 		} else
 			rv = 1; /* unspecified source; tentatively allow */
 	}
-	rcu_read_unlock();
 	return rv;
 }
 

net/ipv4/route.c

@@ -2309,7 +2309,7 @@ int ip_route_input_common(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 		struct in_device *in_dev = __in_dev_get_rcu(dev);
 
 		if (in_dev) {
-			int our = ip_check_mc(in_dev, daddr, saddr,
+			int our = ip_check_mc_rcu(in_dev, daddr, saddr,
 						  ip_hdr(skb)->protocol);
 			if (our
 #ifdef CONFIG_IP_MROUTE
@@ -2368,7 +2368,7 @@ static struct rtable *__mkroute_output(const struct fib_result *res,
 		fi = NULL;
 	} else if (type == RTN_MULTICAST) {
 		flags |= RTCF_MULTICAST | RTCF_LOCAL;
-		if (!ip_check_mc(in_dev, oldflp->fl4_dst, oldflp->fl4_src,
+		if (!ip_check_mc_rcu(in_dev, oldflp->fl4_dst, oldflp->fl4_src,
 				     oldflp->proto))
 			flags &= ~RTCF_LOCAL;
 		/* If multicast route do not exist use