netdev - [PATCH v1 net-next 08/15] ipv6: mcast: Don't hold RTNL in ipv6_sock_mc

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Message-ID: <20250616233417.1153427-9-kuni1840@gmail.com>
Date: Mon, 16 Jun 2025 16:28:37 -0700
From: Kuniyuki Iwashima <kuni1840@...il.com>
To: "David S. Miller" <davem@...emloft.net>,
	David Ahern <dsahern@...nel.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>
Cc: Simon Horman <horms@...nel.org>,
	Kuniyuki Iwashima <kuniyu@...gle.com>,
	Kuniyuki Iwashima <kuni1840@...il.com>,
	netdev@...r.kernel.org
Subject: [PATCH v1 net-next 08/15] ipv6: mcast: Don't hold RTNL in ipv6_sock_mc_close().

From: Kuniyuki Iwashima <kuniyu@...gle.com>

In __ipv6_sock_mc_close(), per-socket mld data is protected by lock_sock(),
and only __dev_get_by_index() and __in6_dev_get() require RTNL.

Let's call __ipv6_sock_mc_drop() and drop RTNL in ipv6_sock_mc_close().

Signed-off-by: Kuniyuki Iwashima <kuniyu@...gle.com>
---
 net/ipv6/mcast.c | 22 +---------------------
 1 file changed, 1 insertion(+), 21 deletions(-)

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 7324e9bc2163..84c7ed23bc2d 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -332,28 +332,10 @@ void __ipv6_sock_mc_close(struct sock *sk)
 {
 	struct ipv6_pinfo *np = inet6_sk(sk);
 	struct ipv6_mc_socklist *mc_lst;
-	struct net *net = sock_net(sk);
-
-	ASSERT_RTNL();
 
 	while ((mc_lst = sock_dereference(np->ipv6_mc_list, sk)) != NULL) {
-		struct net_device *dev;
-
 		np->ipv6_mc_list = mc_lst->next;
-
-		dev = __dev_get_by_index(net, mc_lst->ifindex);
-		if (dev) {
-			struct inet6_dev *idev = __in6_dev_get(dev);
-
-			ip6_mc_leave_src(sk, mc_lst, idev);
-			if (idev)
-				__ipv6_dev_mc_dec(idev, &mc_lst->addr);
-		} else {
-			ip6_mc_leave_src(sk, mc_lst, NULL);
-		}
-
-		atomic_sub(sizeof(*mc_lst), &sk->sk_omem_alloc);
-		kfree_rcu(mc_lst, rcu);
+		__ipv6_sock_mc_drop(sk, mc_lst);
 	}
 }
 
@@ -364,11 +346,9 @@ void ipv6_sock_mc_close(struct sock *sk)
 	if (!rcu_access_pointer(np->ipv6_mc_list))
 		return;
 
-	rtnl_lock();
 	lock_sock(sk);
 	__ipv6_sock_mc_close(sk);
 	release_sock(sk);
-	rtnl_unlock();
 }
 
 int ip6_mc_source(int add, int omode, struct sock *sk,
-- 
2.49.0