netdev - [PATCH net,v3, 2/2] hv_netvsc: Fix race of register_netdevice

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Date: Tue,  7 Nov 2023 13:05:32 -0800
From: Haiyang Zhang <haiyangz@...rosoft.com>
To: linux-hyperv@...r.kernel.org,
	netdev@...r.kernel.org
Cc: haiyangz@...rosoft.com,
	kys@...rosoft.com,
	wei.liu@...nel.org,
	decui@...rosoft.com,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	davem@...emloft.net,
	linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: [PATCH net,v3, 2/2] hv_netvsc: Fix race of register_netdevice_notifier and VF register

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@...r.kernel.org
Fixes: e04e7a7bbd4b ("hv_netvsc: Fix a deadlock by getting rtnl lock earlier in netvsc_probe()")
Signed-off-by: Haiyang Zhang <haiyangz@...rosoft.com>
Reviewed-by: Wojciech Drewek <wojciech.drewek@...el.com>

---
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