net: reinstate rtnl in call_netdevice_notifiers()
Eric Biederman pointed out that not holding RTNL while calling
call_netdevice_notifiers() was racy.
This patch is a direct transcription his feedback
against commit 0115e8e30d6fc (net: remove delay at device dismantle)
Thanks Eric !
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Mahesh Bandewar <maheshb@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Gao feng <gaofeng@cn.fujitsu.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev.c b/net/core/dev.c
index 0640d2a..bc857fe 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1466,8 +1466,7 @@
int call_netdevice_notifiers(unsigned long val, struct net_device *dev)
{
- if (val != NETDEV_UNREGISTER_FINAL)
- ASSERT_RTNL();
+ ASSERT_RTNL();
return raw_notifier_call_chain(&netdev_chain, val, dev);
}
EXPORT_SYMBOL(call_netdevice_notifiers);
@@ -5782,7 +5781,11 @@
/* Rebroadcast unregister notification */
call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
+
+ __rtnl_unlock();
rcu_barrier();
+ rtnl_lock();
+
call_netdevice_notifiers(NETDEV_UNREGISTER_FINAL, dev);
if (test_bit(__LINK_STATE_LINKWATCH_PENDING,
&dev->state)) {
@@ -5855,7 +5858,9 @@
= list_first_entry(&list, struct net_device, todo_list);
list_del(&dev->todo_list);
+ rtnl_lock();
call_netdevice_notifiers(NETDEV_UNREGISTER_FINAL, dev);
+ __rtnl_unlock();
if (unlikely(dev->reg_state != NETREG_UNREGISTERING)) {
pr_err("network todo '%s' but state %d\n",