Re: [PATCH net] hv_netvsc: fix race of netvsc and VF register_netdevice

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.

• }
• eth_hw_addr_set(net, device_info->mac_adr);
• if (nvdev->num_chn > 1) schedule_work(&nvdev->subchan_work);

@@ -2788,11 +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;

}