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: [email protected]
> Fixes: e04e7a7bbd4b ("hv_netvsc: Fix a deadlock by getting rtnl lock earlier
> in netvsc_probe()")
> Signed-off-by: Haiyang Zhang <[email protected]>
>
> ---
> 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;
> }
>
