[Devel] Re: [PATCH 1/2] SYSCTL: root unregister routine introduced

[Glauber Costa]

On 12/13/2011 01:02 PM, Stanislav Kinsbursky wrote:
> 13.12.2011 02:52, Andrew Morton пишет:
>> On Mon, 12 Dec 2011 21:50:00 +0300
>> Stanislav Kinsbursky<skinsbursky at parallels.com> wrote:
>>
>>> This routine is required for SUNRPC sysctl's, which are going to be
>>> allocated,
>>> processed and destroyed per network namespace context.
>>> IOW, new sysctl root will be registered on network namespace creation
>>> and
>>> thus have to unregistered before network namespace destruction.
>>>
>>
>> It's a bit suspicious that such a mature subsystem as sysctl newly
>> needs its internals exported like this. Either a) the net namespaces
>> work is doing something which hasn't been done before or b) it is doing
>> something wrong.
>>
>> So, please explain further so we can confirm that it is a) and not b).
>>
>
> Hello, Andrew.
> The goal is to provide an ability to control and modify data by sysctl's
> in network namespace context. This is done by "net" sysctl's.
> But there are two more issues to solve:
> 1) Sysctl's have to be in /proc/sys/sunrpc
> 2) Sysctl's content should be accessible from creator's network context
> (not current user ones's).
>

Have you taken a look at how it is done at net/ipv4/sysctl_tcp_ipv4.c , 
for instance?

It manages to handle a per-net sysctl table without touching a single 
bit at the kernel's core sysctl routines. Not entirely sure if it would 
fit your use case, but maybe it is worth taking a look.

That file achieves both 1) and 2) that you described...