hv_netvsc: fix race of netvsc and VF register_netdevice

commit d30fb712e52964f2cf9a9c14cf67078394044837 upstream.

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.

Cc: stable@vger.kernel.org
Fixes: e04e7a7bbd4b ("hv_netvsc: Fix a deadlock by getting rtnl lock earlier in netvsc_probe()")
Reported-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: Wojciech Drewek <wojciech.drewek@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 3ba3c8f..5e528a7 100644 (file)
--- 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;
+       }
+
+       eth_hw_addr_set(net, device_info->mac_adr);
+
        if (nvdev->num_chn > 1)
                schedule_work(&nvdev->subchan_work);
 
@@ -2586,9 +2591,9 @@ static int netvsc_probe(struct hv_device *dev,
        return 0;
 
 register_failed:
-       rtnl_unlock();
        rndis_filter_device_remove(dev, nvdev);
 rndis_failed:
+       rtnl_unlock();
        netvsc_devinfo_put(device_info);
 devinfo_failed:
        free_percpu(net_device_ctx->vf_stats);