linux-kernel - [PATCH net,v5, 2/3] hv_netvsc: Fix race of register_netdevice

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Date:   Sun, 19 Nov 2023 08:23:42 -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, stephen@...workplumber.org, davem@...emloft.net,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: [PATCH net,v5, 2/3] 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()")
Reported-by: Dexuan Cui <decui@...rosoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@...rosoft.com>
Reviewed-by: Wojciech Drewek <wojciech.drewek@...el.com>
Reviewed-by: Dexuan Cui <decui@...rosoft.com>

---
v5:
  Use a more idiomatic form for the error path, suggested by Simon Horman.
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 | 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 5e528a76f5f5..b7dfd51f09e6 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -2793,12 +2793,17 @@ 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