RE: [PATCH v3] hv_netvsc: Add per-cpu ethtool stats for netvsc

From: Yidong Ren
Date: Wed Jul 25 2018 - 18:54:13 EST


> From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> While you do for_each_present_cpu() in netvsc_get_ethtool_stats(),
> netvsc_get_pcpu_stats() does for_each_possible_cpu(). This looks
> inconsistent.

I made a mistake there. Thanks for catch me.

> The allocation you're doing here is short-lived so I would suggest you use
> possible_cpus everywhere. Even knowing there's no CPU hotplug on Hyper-
> V at this moment, it can appear later and we'll get a hard-to-find issue.
> Moreover, we may consider using netvsc driver on e.g. KVM with Hyper-V
> enlightenments and KVM has CPU hotplug already.

That would cause the output to be very long and useless.
I will submit a revision that allocates for num_possible_cpus, but only copy out stats for each present cpu.

-Yidong