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

[Tim Gardner]

From: Haiyang Zhang <haiyangz at microsoft.com>

BugLink: https://bugs.launchpad.net/bugs/2045069

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 at vger.kernel.org
Fixes: e04e7a7bbd4b ("hv_netvsc: Fix a deadlock by getting rtnl lock earlier in netvsc_probe()")
Reported-by: Dexuan Cui <decui at microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz at microsoft.com>
Reviewed-by: Wojciech Drewek <wojciech.drewek at intel.com>
Reviewed-by: Dexuan Cui <decui at microsoft.com>
Signed-off-by: Paolo Abeni <pabeni at redhat.com>
(cherry picked from commit 85520856466ed6bc3b1ccb013cddac70ceb437db)
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
---
 drivers/net/hyperv/netvsc_drv.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index e247cd70e8a9..f62aea09adcc 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -2786,12 +2786,17 @@ 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)
-		return ret;
+		goto err_vmbus_reg;
 
-	register_netdevice_notifier(&netvsc_netdev_notifier);
 	return 0;
+
+err_vmbus_reg:
+	unregister_netdevice_notifier(&netvsc_netdev_notifier);
+	return ret;
 }
 
 MODULE_LICENSE("GPL");
-- 
2.34.1