netdev - [PATCH v1 net-next 05/15] ipv6: mcast: Use in6_dev_get() in ipv6_dev_mc

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Message-ID: <20250616233417.1153427-6-kuni1840@gmail.com>
Date: Mon, 16 Jun 2025 16:28:34 -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 05/15] ipv6: mcast: Use in6_dev_get() in ipv6_dev_mc_dec().

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

As well as __ipv6_dev_mc_inc(), all code in __ipv6_dev_mc_dec() are
protected by inet6_dev->mc_lock, and RTNL is not needed.

Let's use in6_dev_get() in ipv6_dev_mc_dec() and remove ASSERT_RTNL()
in __ipv6_dev_mc_dec().

Now, we can remove the RTNL comment above addrconf_leave_solict() too.

Signed-off-by: Kuniyuki Iwashima <kuniyu@...gle.com>
---
 net/ipv6/addrconf.c |  3 +--
 net/ipv6/mcast.c    | 14 ++++++--------
 2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index e4c48638211b..78ee68771229 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -2241,12 +2241,11 @@ void addrconf_join_solict(struct net_device *dev, const struct in6_addr *addr)
 	ipv6_dev_mc_inc(dev, &maddr);
 }
 
-/* caller must hold RTNL */
 void addrconf_leave_solict(struct inet6_dev *idev, const struct in6_addr *addr)
 {
 	struct in6_addr maddr;
 
-	if (idev->dev->flags&(IFF_LOOPBACK|IFF_NOARP))
+	if (READ_ONCE(idev->dev->flags) & (IFF_LOOPBACK | IFF_NOARP))
 		return;
 
 	addrconf_addr_solict_mult(addr, &maddr);
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index aa1280df4c1f..b3f063b5ffd7 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1004,9 +1004,8 @@ int __ipv6_dev_mc_dec(struct inet6_dev *idev, const struct in6_addr *addr)
 {
 	struct ifmcaddr6 *ma, __rcu **map;
 
-	ASSERT_RTNL();
-
 	mutex_lock(&idev->mc_lock);
+
 	for (map = &idev->mc_list;
 	     (ma = mc_dereference(*map, idev));
 	     map = &ma->next) {
@@ -1037,13 +1036,12 @@ int ipv6_dev_mc_dec(struct net_device *dev, const struct in6_addr *addr)
 	struct inet6_dev *idev;
 	int err;
 
-	ASSERT_RTNL();
-
-	idev = __in6_dev_get(dev);
+	idev = in6_dev_get(dev);
 	if (!idev)
-		err = -ENODEV;
-	else
-		err = __ipv6_dev_mc_dec(idev, addr);
+		return -ENODEV;
+
+	err = __ipv6_dev_mc_dec(idev, addr);
+	in6_dev_put(idev);
 
 	return err;
 }
-- 
2.49.0