From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH] ipv6 addrconf: enable use of proc_dointvec_minmax in
 addrconf_sysctl
Date: Wed, 28 Sep 2016 07:52:04 -0400 (EDT)
Message-ID: <20160928.075204.140017839812712683.davem@davemloft.net>
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From: David Miller <davem@davemloft.net>
Date: Wed, 28 Sep 2016 07:49:01 -0400 (EDT)

> From: Maciej Żenczykowski <zenczykowski@gmail.com>
> Date: Tue, 27 Sep 2016 05:16:45 -0700
> 
>> From: Maciej Żenczykowski <maze@google.com>
>> 
>> Signed-off-by: Maciej Żenczykowski <maze@google.com>
> 
> I was about to ask you to submit this patch alongside an actual
> addition of a proc_dointvec_minmax user to the table.
> 
> But upon second checking there is one, indirectly via
> addrconf_sysctl_mtu().

And actually these cases use a dummy sysctl blob on the stack to
provide the min/max values to proc_dointvec_minmax.  And they do
it _EXACTLY_ because the extra pointers are for the netns pointer
and a pointer to the idev.

And any user envisioned can do the same thing, use a trampoline
like the existing cases do.