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>

1 files changed, 1 insertions, 5 deletions

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 6a5e6e4b142c..adf273f8ad2e 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1147,12 +1147,8 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
                          void *ptr)
 {
         struct net_device *dev = ptr;
-        struct in_device *in_dev;
-
-        if (event == NETDEV_UNREGISTER_FINAL)
-                goto out;
+        struct in_device *in_dev = __in_dev_get_rtnl(dev);
 
-        in_dev = __in_dev_get_rtnl(dev);
         ASSERT_RTNL();
 
         if (!in_dev) {