[PATCH v1 net-next 04/14] net: Wrap default_device_exit_net() with __rtnl_net_lock().

[Kuniyuki Iwashima <kuniyu@google.com>]

default_device_exit_net() could call dev_change_net_namespace()
to move devices from a dying netns to init_net.

Let's hold the two netns __rtnl_net_lock() around it.

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
---
 net/core/dev.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 4b3d5cfdf6e0..c477c4f84ed9 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -13034,7 +13034,7 @@ static void __net_exit default_device_exit_net(struct net *net)
 	 * Push all migratable network devices back to the
 	 * initial network namespace
 	 */
-	ASSERT_RTNL();
+
 	for_each_netdev_safe(net, dev, aux) {
 		int err;
 		char fb_name[IFNAMSIZ];
@@ -13077,11 +13077,19 @@ static void __net_exit default_device_exit_batch(struct list_head *net_list)
 	LIST_HEAD(dev_kill_list);
 
 	rtnl_lock();
+
+	__rtnl_net_lock(&init_net);
+
 	list_for_each_entry(net, net_list, exit_list) {
+		__rtnl_net_lock(net);
 		default_device_exit_net(net);
+		__rtnl_net_unlock(net);
+
 		cond_resched();
 	}
 
+	__rtnl_net_unlock(&init_net);
+
 	list_for_each_entry(net, net_list, exit_list) {
 		for_each_netdev_reverse(net, dev) {
 			if (dev->rtnl_link_ops && dev->rtnl_link_ops->dellink)
-- 
2.55.0.rc0.799.gd6f94ed593-goog