From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH v5 2/2] sock: Move the socket inuse to namespace.
Date: Thu, 07 Dec 2017 09:20:08 -0800
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To: Tonghao Zhang <xiangxia.m.yue@gmail.com>, davem@davemloft.net,
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On Thu, 2017-12-07 at 08:45 -0800, Tonghao Zhang wrote:
> In some case, we want to know how many sockets are in use in
> different _net_ namespaces. It's a key resource metric.
> 

...

> +static void sock_inuse_add(struct net *net, int val)
> +{
> +	if (net->core.prot_inuse)
> +		this_cpu_add(*net->core.sock_inuse, val);
> +}

This is very confusing.

Why testing net->core.prot_inuse for NULL is needed at all ?

Why not testing net->core.sock_inuse instead ?