We will replace RTNL with a per-netns mutex to protect dev->mpls_ptr.

Then, we will use rcu_dereference_protected() with the lockdep_is_held()
annotation, which requires net to access the per-netns mutex.

However, dev_net(dev) is not safe without RTNL.

Let's pass net to mpls_dev_get().

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
---
 net/mpls/af_mpls.c  | 11 ++++++-----
 net/mpls/internal.h |  3 ++-
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index 10130b90c439..a715b12860e9 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -708,7 +708,7 @@ static int mpls_nh_assign_dev(struct net *net, struct mpls_route *rt,
 
 	/* Ensure this is a supported device */
 	err = -EINVAL;
-	if (!mpls_dev_get(dev))
+	if (!mpls_dev_get(net, dev))
 		goto errout_put;
 
 	if ((nh->nh_via_table == NEIGH_LINK_TABLE) &&
@@ -1288,7 +1288,7 @@ static int mpls_netconf_get_devconf(struct sk_buff *in_skb,
 	if (!dev)
 		goto errout;
 
-	mdev = mpls_dev_get(dev);
+	mdev = mpls_dev_get(net, dev);
 	if (!mdev)
 		goto errout;
 
@@ -1611,6 +1611,7 @@ static int mpls_dev_notify(struct notifier_block *this, unsigned long event,
 			   void *ptr)
 {
 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+	struct net *net = dev_net(dev);
 	struct mpls_dev *mdev;
 	unsigned int flags;
 	int err;
@@ -1625,7 +1626,7 @@ static int mpls_dev_notify(struct notifier_block *this, unsigned long event,
 		goto out;
 	}
 
-	mdev = mpls_dev_get(dev);
+	mdev = mpls_dev_get(net, dev);
 	if (!mdev)
 		goto out;
 
@@ -1658,7 +1659,7 @@ static int mpls_dev_notify(struct notifier_block *this, unsigned long event,
 		if (err)
 			goto err;
 
-		mdev = mpls_dev_get(dev);
+		mdev = mpls_dev_get(net, dev);
 		if (mdev) {
 			mpls_dev_sysctl_unregister(dev, mdev);
 			RCU_INIT_POINTER(dev->mpls_ptr, NULL);
@@ -1666,7 +1667,7 @@ static int mpls_dev_notify(struct notifier_block *this, unsigned long event,
 		}
 		break;
 	case NETDEV_CHANGENAME:
-		mdev = mpls_dev_get(dev);
+		mdev = mpls_dev_get(net, dev);
 		if (mdev) {
 			mpls_dev_sysctl_unregister(dev, mdev);
 			err = mpls_dev_sysctl_register(dev, mdev);
diff --git a/net/mpls/internal.h b/net/mpls/internal.h
index 080e82010022..0df01a5395ee 100644
--- a/net/mpls/internal.h
+++ b/net/mpls/internal.h
@@ -190,7 +190,8 @@ static inline struct mpls_dev *mpls_dev_rcu(const struct net_device *dev)
 	return rcu_dereference(dev->mpls_ptr);
 }
 
-static inline struct mpls_dev *mpls_dev_get(const struct net_device *dev)
+static inline struct mpls_dev *mpls_dev_get(const struct net *net,
+					    const struct net_device *dev)
 {
 	return rcu_dereference_rtnl(dev->mpls_ptr);
 }
-- 
2.51.1.851.g4ebd6896fd-goog