hv_netvsc: Implement set_channels ethtool op

Hello Andrew Schwartzmeyer,

This is a semi-automatic email about new static checker warnings.

The patch b5960e6e2b5c: "hv_netvsc: Implement set_channels ethtool op" from Aug 11, 2015, leads to the following Smatch complaint:

drivers/net/hyperv/netvsc_drv.c:785 netvsc_set_channels()
warn: variable dereferenced before check 'nvdev' (see line 780)

drivers/net/hyperv/netvsc_drv.c
779 struct netvsc_device_info device_info;

   780		const u32 num_chn = nvdev->num_chn;
                                    ^^^^^^^^^^^^^^

Deref.

   781		const u32 max_chn = min_t(u32, nvdev->max_chn, num_online_cpus());
                                               ^^^^^^^^^^^^^^

Deref.

782 int ret = 0;
783 bool recovering = false;
784
785 if (!nvdev || nvdev->destroy)

                     ^^^^^

Check too late.

786 return -ENODEV;
787

regards,
dan carpenter