[Devel] Re: [PATCH 0/5] Make nicer CONFIG_NET_NS=n case code

[Eric Dumazet]

On Wed, 31 Oct 2007 22:19:43 +0300
Pavel Emelyanov <xemul at openvz.org> wrote:

> Currently we have the NET_NS config option, but the only change it 
> makes is just return ERR_PTR(-EINVAL) inside the cloning call thus
> introducing a bunch of a dead code and making the reference counting
> unneeded. This is not very good.
> 
> So clean the net_namespace.c to fix this.
> 
> I have sent a set of patches to Andrew to make similar thing for
> other namespaces, which introduces the NAMESPACES option to turn
> all the namespaces off at once (to make embedded people suffer
> less). So after that stuff is in, there will be some more patches 
> to tie all this together.
> 
> What is to be done after this set is to make the register_pernet_xxx
> stuff smaller. Currently this code weights approximately 500 bytes, 
> so it worths reducing it, but I haven't found a good solution yet.

Definitly wanted here. Thank you.
One more refcounting on each socket creation/deletion was expensive.

Maybe we can add a macro to get nd_net from a "struct net_device"
so that every instance of

if (dev->nd_net != &init_net)
    goto drop;

can also be optimized away if !CONFIG_NET_NS

extern inline netdev_get_ns(struct netdevice *dev)
{
#ifdef CONFIG_NET_NS
	return dev->nd_net;
#else
	return &init_net;
#endif
}

...

if (netdev_get_ns(dev) != &init_net)
	goto drop;