ipv6: mcast: Add ip6_mc_find_idev() helper

Extract the same code logic from __ipv6_sock_mc_join() and
ip6_mc_find_dev(), also add new helper ip6_mc_find_idev() to
reduce redundancy and enhance readability.

No functional changes intended.

Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Reviewed-by: Dawid Osuchowski <dawid.osuchowski@linux.intel.com>
Link: https://patch.msgid.link/20250822064051.2991480-1-yuehaibing@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 31 insertions, 36 deletions

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 36ca27496b3c..55c49dc14b1b 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -169,6 +169,29 @@ static int unsolicited_report_interval(struct inet6_dev *idev)
 	return iv > 0 ? iv : 1;
 }
 
+static struct net_device *ip6_mc_find_dev(struct net *net,
+					  const struct in6_addr *group,
+					  int ifindex)
+{
+	struct net_device *dev = NULL;
+	struct rt6_info *rt;
+
+	if (ifindex == 0) {
+		rcu_read_lock();
+		rt = rt6_lookup(net, group, NULL, 0, NULL, 0);
+		if (rt) {
+			dev = dst_dev(&rt->dst);
+			dev_hold(dev);
+			ip6_rt_put(rt);
+		}
+		rcu_read_unlock();
+	} else {
+		dev = dev_get_by_index(net, ifindex);
+	}
+
+	return dev;
+}
+
 /*
  *	socket join on multicast group
  */
@@ -191,28 +214,13 @@ static int __ipv6_sock_mc_join(struct sock *sk, int ifindex,
 	}
 
 	mc_lst = sock_kmalloc(sk, sizeof(struct ipv6_mc_socklist), GFP_KERNEL);
-
 	if (!mc_lst)
 		return -ENOMEM;
 
 	mc_lst->next = NULL;
 	mc_lst->addr = *addr;
 
-	if (ifindex == 0) {
-		struct rt6_info *rt;
-
-		rcu_read_lock();
-		rt = rt6_lookup(net, addr, NULL, 0, NULL, 0);
-		if (rt) {
-			dev = dst_dev(&rt->dst);
-			dev_hold(dev);
-			ip6_rt_put(rt);
-		}
-		rcu_read_unlock();
-	} else {
-		dev = dev_get_by_index(net, ifindex);
-	}
-
+	dev = ip6_mc_find_dev(net, addr, ifindex);
 	if (!dev) {
 		sock_kfree_s(sk, mc_lst, sizeof(*mc_lst));
 		return -ENODEV;
@@ -302,27 +310,14 @@ int ipv6_sock_mc_drop(struct sock *sk, int ifindex, const struct in6_addr *addr)
 }
 EXPORT_SYMBOL(ipv6_sock_mc_drop);
 
-static struct inet6_dev *ip6_mc_find_dev(struct net *net,
-					 const struct in6_addr *group,
-					 int ifindex)
+static struct inet6_dev *ip6_mc_find_idev(struct net *net,
+					  const struct in6_addr *group,
+					  int ifindex)
 {
-	struct net_device *dev = NULL;
+	struct net_device *dev;
 	struct inet6_dev *idev;
 
-	if (ifindex == 0) {
-		struct rt6_info *rt;
-
-		rcu_read_lock();
-		rt = rt6_lookup(net, group, NULL, 0, NULL, 0);
-		if (rt) {
-			dev = dst_dev(&rt->dst);
-			dev_hold(dev);
-			ip6_rt_put(rt);
-		}
-		rcu_read_unlock();
-	} else {
-		dev = dev_get_by_index(net, ifindex);
-	}
+	dev = ip6_mc_find_dev(net, group, ifindex);
 	if (!dev)
 		return NULL;
 
@@ -374,7 +369,7 @@ int ip6_mc_source(int add, int omode, struct sock *sk,
 	if (!ipv6_addr_is_multicast(group))
 		return -EINVAL;
 
-	idev = ip6_mc_find_dev(net, group, pgsr->gsr_interface);
+	idev = ip6_mc_find_idev(net, group, pgsr->gsr_interface);
 	if (!idev)
 		return -ENODEV;
 
@@ -509,7 +504,7 @@ int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf,
 	    gsf->gf_fmode != MCAST_EXCLUDE)
 		return -EINVAL;
 
-	idev = ip6_mc_find_dev(net, group, gsf->gf_interface);
+	idev = ip6_mc_find_idev(net, group, gsf->gf_interface);
 	if (!idev)
 		return -ENODEV;