net: use netif_disable_lro in ipv6_add_dev

ipv6_add_dev might call dev_disable_lro which unconditionally grabs
instance lock, so it will deadlock during NETDEV_REGISTER. Switch
to netif_disable_lro.

Make sure all callers hold the instance lock as well.

Cc: Cosmin Ratiu <cratiu@nvidia.com>
Fixes: ad7c7b2 ("net: hold netdev instance lock during sysfs operations")
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250401163452.622454-4-sdf@fomichev.me
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/ip.h

@@ -667,14 +667,6 @@ static inline void ip_ipgre_mc_map(__be32 naddr, const unsigned char *broadcast,
 		memcpy(buf, &naddr, sizeof(naddr));
 }
 
-#if IS_MODULE(CONFIG_IPV6)
-#define EXPORT_IPV6_MOD(X) EXPORT_SYMBOL(X)
-#define EXPORT_IPV6_MOD_GPL(X) EXPORT_SYMBOL_GPL(X)
-#else
-#define EXPORT_IPV6_MOD(X)
-#define EXPORT_IPV6_MOD_GPL(X)
-#endif
-
 #if IS_ENABLED(CONFIG_IPV6)
 #include <linux/ipv6.h>
 #endif
@@ -694,6 +686,14 @@ static __inline__ void inet_reset_saddr(struct sock *sk)
 
 #endif
 
+#if IS_MODULE(CONFIG_IPV6)
+#define EXPORT_IPV6_MOD(X) EXPORT_SYMBOL(X)
+#define EXPORT_IPV6_MOD_GPL(X) EXPORT_SYMBOL_GPL(X)
+#else
+#define EXPORT_IPV6_MOD(X)
+#define EXPORT_IPV6_MOD_GPL(X)
+#endif
+
 static inline unsigned int ipv4_addr_hash(__be32 ip)
 {
 	return (__force unsigned int) ip;

net/core/dev.c

@@ -1771,6 +1771,7 @@ void netif_disable_lro(struct net_device *dev)
 		netdev_unlock_ops(lower_dev);
 	}
 }
+EXPORT_IPV6_MOD(netif_disable_lro);
 
 /**
  *	dev_disable_gro_hw - disable HW Generic Receive Offload on a device

net/ipv6/addrconf.c

@@ -80,6 +80,7 @@
 #include <net/netlink.h>
 #include <net/pkt_sched.h>
 #include <net/l3mdev.h>
+#include <net/netdev_lock.h>
 #include <linux/if_tunnel.h>
 #include <linux/rtnetlink.h>
 #include <linux/netconf.h>
@@ -377,6 +378,7 @@ static struct inet6_dev *ipv6_add_dev(struct net_device *dev)
 	int err = -ENOMEM;
 
 	ASSERT_RTNL();
+	netdev_ops_assert_locked(dev);
 
 	if (dev->mtu < IPV6_MIN_MTU && dev != blackhole_netdev)
 		return ERR_PTR(-EINVAL);
@@ -402,7 +404,7 @@ static struct inet6_dev *ipv6_add_dev(struct net_device *dev)
 		return ERR_PTR(err);
 	}
 	if (ndev->cnf.forwarding)
-		dev_disable_lro(dev);
+		netif_disable_lro(dev);
 	/* We refer to the device */
 	netdev_hold(dev, &ndev->dev_tracker, GFP_KERNEL);
 
@@ -3152,10 +3154,12 @@ int addrconf_add_ifaddr(struct net *net, void __user *arg)
 
 	rtnl_net_lock(net);
 	dev = __dev_get_by_index(net, ireq.ifr6_ifindex);
+	netdev_lock_ops(dev);
 	if (dev)
 		err = inet6_addr_add(net, dev, &cfg, 0, 0, NULL);
 	else
 		err = -ENODEV;
+	netdev_unlock_ops(dev);
 	rtnl_net_unlock(net);
 	return err;
 }
@@ -5026,9 +5030,10 @@ inet6_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (!dev) {
 		NL_SET_ERR_MSG_MOD(extack, "Unable to find the interface");
 		err = -ENODEV;
-		goto unlock;
+		goto unlock_rtnl;
 	}
 
+	netdev_lock_ops(dev);
 	idev = ipv6_find_idev(dev);
 	if (IS_ERR(idev)) {
 		err = PTR_ERR(idev);
@@ -5065,6 +5070,8 @@ inet6_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh,
 
 	in6_ifa_put(ifa);
 unlock:
+	netdev_unlock_ops(dev);
+unlock_rtnl:
 	rtnl_net_unlock(net);
 
 	return err;
@@ -6516,7 +6523,9 @@ static int addrconf_sysctl_addr_gen_mode(const struct ctl_table *ctl, int write,
 
 			if (idev->cnf.addr_gen_mode != new_val) {
 				WRITE_ONCE(idev->cnf.addr_gen_mode, new_val);
+				netdev_lock_ops(idev->dev);
 				addrconf_init_auto_addrs(idev->dev);
+				netdev_unlock_ops(idev->dev);
 			}
 		} else if (&net->ipv6.devconf_all->addr_gen_mode == ctl->data) {
 			struct net_device *dev;
@@ -6528,7 +6537,9 @@ static int addrconf_sysctl_addr_gen_mode(const struct ctl_table *ctl, int write,
 				    idev->cnf.addr_gen_mode != new_val) {
 					WRITE_ONCE(idev->cnf.addr_gen_mode,
 						  new_val);
+					netdev_lock_ops(idev->dev);
 					addrconf_init_auto_addrs(idev->dev);
+					netdev_unlock_ops(idev->dev);
 				}
 			}
 		}