[PATCH net,v4, 2/3] hv_netvsc: Fix race of register_netdevice_notifier and VF register

[Haiyang Zhang]

If VF NIC is registered earlier, NETDEV_REGISTER event is replayed,
but NETDEV_POST_INIT is not.

Move register_netdevice_notifier() earlier, so the call back
function is set before probing.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: e04e7a7bbd4b ("hv_netvsc: Fix a deadlock by getting rtnl lock earlier in netvsc_probe()")
Reported-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
Signed-off-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
Reviewed-by: Wojciech Drewek <wojciech.drewek@xxxxxxxxx>

---
v3:
  Divide it into two patches, suggested by Jakub Kicinski.
v2:
  Fix rtnl_unlock() in error handling as found by Wojciech Drewek.
---
 drivers/net/hyperv/netvsc_drv.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 5e528a76f5f5..1d1491da303b 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -2793,11 +2793,14 @@ static int __init netvsc_drv_init(void)
 	}
 	netvsc_ring_bytes = ring_size * PAGE_SIZE;
 
+	register_netdevice_notifier(&netvsc_netdev_notifier);
+
 	ret = vmbus_driver_register(&netvsc_drv);
-	if (ret)
+	if (ret) {
+		unregister_netdevice_notifier(&netvsc_netdev_notifier);
 		return ret;
+	}
 
-	register_netdevice_notifier(&netvsc_netdev_notifier);
 	return 0;
 }
 
-- 
2.25.1