[PATCH NET-PREV 29/51] ip6gre: Use __register_netdevice() in .changelink

[Kirill Tkhai <tkhai@ya.ru>]

The objective is to conform .changelink with its callers,
which already assign nd_lock (and matches master nd_lock
if there is one).

Signed-off-by: Kirill Tkhai <tkhai@ya.ru>
---
 net/ipv6/ip6_gre.c |   26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 57cbf7942dc8..e40780da15a0 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -344,6 +344,7 @@ static struct ip6_tnl *ip6gre_tunnel_find(struct net *net,
 }
 
 static struct ip6_tnl *ip6gre_tunnel_locate(struct net *net,
+		struct nd_lock *nd_lock,
 		const struct __ip6_tnl_parm *parms, int create)
 {
 	struct ip6_tnl *t, *nt;
@@ -378,8 +379,11 @@ static struct ip6_tnl *ip6gre_tunnel_locate(struct net *net,
 	nt->dev = dev;
 	nt->net = dev_net(dev);
 
-	if (register_netdevice(dev) < 0)
+	attach_nd_lock(dev, nd_lock);
+	if (__register_netdevice(dev) < 0) {
+		detach_nd_lock(dev);
 		goto failed_free;
+	}
 
 	ip6gre_tnl_link_config(nt, 1);
 	ip6gre_tunnel_link(ign, nt);
@@ -1277,6 +1281,10 @@ static void ip6gre_tnl_parm_to_user(struct ip6_tnl_parm2 *u,
 	memcpy(u->name, p->name, sizeof(u->name));
 }
 
+/* XXX: Currently ->ndo_siocdevprivate is called with @dev unlocked
+ * (the only place where @dev may be locked is phonet_device_autoconf(),
+ *  but it can't be caller of this).
+ */
 static int ip6gre_tunnel_siocdevprivate(struct net_device *dev,
 					struct ifreq *ifr, void __user *data,
 					int cmd)
@@ -1287,6 +1295,7 @@ static int ip6gre_tunnel_siocdevprivate(struct net_device *dev,
 	struct ip6_tnl *t = netdev_priv(dev);
 	struct net *net = t->net;
 	struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);
+	struct nd_lock *nd_lock;
 
 	memset(&p1, 0, sizeof(p1));
 
@@ -1298,7 +1307,9 @@ static int ip6gre_tunnel_siocdevprivate(struct net_device *dev,
 				break;
 			}
 			ip6gre_tnl_parm_from_user(&p1, &p);
-			t = ip6gre_tunnel_locate(net, &p1, 0);
+			lock_netdev(dev, &nd_lock);
+			t = ip6gre_tunnel_locate(net, nd_lock, &p1, 0);
+			unlock_netdev(nd_lock);
 			if (!t)
 				t = netdev_priv(dev);
 		}
@@ -1328,7 +1339,9 @@ static int ip6gre_tunnel_siocdevprivate(struct net_device *dev,
 			p.o_key = 0;
 
 		ip6gre_tnl_parm_from_user(&p1, &p);
-		t = ip6gre_tunnel_locate(net, &p1, cmd == SIOCADDTUNNEL);
+		lock_netdev(dev, &nd_lock);
+		t = ip6gre_tunnel_locate(net, nd_lock, &p1, cmd == SIOCADDTUNNEL);
+		unlock_netdev(nd_lock);
 
 		if (dev != ign->fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
 			if (t) {
@@ -1369,7 +1382,9 @@ static int ip6gre_tunnel_siocdevprivate(struct net_device *dev,
 				goto done;
 			err = -ENOENT;
 			ip6gre_tnl_parm_from_user(&p1, &p);
-			t = ip6gre_tunnel_locate(net, &p1, 0);
+			lock_netdev(dev, &nd_lock);
+			t = ip6gre_tunnel_locate(net, nd_lock, &p1, 0);
+			unlock_netdev(nd_lock);
 			if (!t)
 				goto done;
 			err = -EPERM;
@@ -2038,6 +2053,7 @@ ip6gre_changelink_common(struct net_device *dev, struct nlattr *tb[],
 			 struct nlattr *data[], struct __ip6_tnl_parm *p_p,
 			 struct netlink_ext_ack *extack)
 {
+	struct nd_lock *nd_lock = rcu_dereference_protected(dev->nd_lock, true);
 	struct ip6_tnl *t, *nt = netdev_priv(dev);
 	struct net *net = nt->net;
 	struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);
@@ -2055,7 +2071,7 @@ ip6gre_changelink_common(struct net_device *dev, struct nlattr *tb[],
 
 	ip6gre_netlink_parms(data, p_p);
 
-	t = ip6gre_tunnel_locate(net, p_p, 0);
+	t = ip6gre_tunnel_locate(net, nd_lock, p_p, 0);
 
 	if (t) {
 		if (t->dev != dev)