-----Original Message----- From: Wojciech Drewek wojciech.drewek@intel.com Sent: Thursday, October 26, 2023 6:48 AM To: Haiyang Zhang haiyangz@microsoft.com; linux-hyperv@vger.kernel.org; netdev@vger.kernel.org Cc: KY Srinivasan kys@microsoft.com; wei.liu@kernel.org; Dexuan Cui decui@microsoft.com; edumazet@google.com; kuba@kernel.org; pabeni@redhat.com; davem@davemloft.net; linux-kernel@vger.kernel.org; stable@vger.kernel.org Subject: Re: [PATCH net] hv_netvsc: fix race of netvsc and VF register_netdevice
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On 25.10.2023 23:16, Haiyang Zhang wrote:
The rtnl lock also needs to be held before rndis_filter_device_add() which advertises nvsp_2_vsc_capability / sriov bit, and triggers VF NIC offering and registering. If VF NIC finished register_netdev() earlier it may cause name based config failure.
To fix this issue, move the call to rtnl_lock() before rndis_filter_device_add(), so VF will be registered later than netvsc / synthetic NIC, and gets a name numbered (ethX) after netvsc.
And, move register_netdevice_notifier() earlier, so the call back function is set before probing.
Cc: stable@vger.kernel.org Fixes: e04e7a7bbd4b ("hv_netvsc: Fix a deadlock by getting rtnl lock earlier
in netvsc_probe()")
Signed-off-by: Haiyang Zhang haiyangz@microsoft.com
drivers/net/hyperv/netvsc_drv.c | 30 +++++++++++++++++++----------- 1 file changed, 19 insertions(+), 11 deletions(-)
diff --git a/drivers/net/hyperv/netvsc_drv.c
b/drivers/net/hyperv/netvsc_drv.c
index 3ba3c8fb28a5..feca1391f756 100644 --- a/drivers/net/hyperv/netvsc_drv.c +++ b/drivers/net/hyperv/netvsc_drv.c @@ -2531,15 +2531,6 @@ static int netvsc_probe(struct hv_device *dev, goto devinfo_failed; }
nvdev = rndis_filter_device_add(dev, device_info);if (IS_ERR(nvdev)) {ret = PTR_ERR(nvdev);netdev_err(net, "unable to add netvsc device (ret %d)\n", ret);goto rndis_failed;}eth_hw_addr_set(net, device_info->mac_adr);/* We must get rtnl lock before scheduling nvdev->subchan_work, * otherwise netvsc_subchan_work() can get rtnl lock first and wait * all subchannels to show up, but that may not happen because@@ -2547,9 +2538,23 @@ static int netvsc_probe(struct hv_device *dev, * -> ... -> device_add() -> ... -> __device_attach() can't get * the device lock, so all the subchannels can't be processed -- * finally netvsc_subchan_work() hangs forever.
** The rtnl lock also needs to be held before rndis_filter_device_add()* which advertises nvsp_2_vsc_capability / sriov bit, and triggers* VF NIC offering and registering. If VF NIC finished register_netdev()* earlier it may cause name based config failure. */ rtnl_lock();nvdev = rndis_filter_device_add(dev, device_info);if (IS_ERR(nvdev)) {ret = PTR_ERR(nvdev);netdev_err(net, "unable to add netvsc device (ret %d)\n", ret);goto rndis_failed;In case of error rtnl won't be unlocked.
Good catch! Will correct this.
Thanks, - Haiyang