Subject: Re: [PATCH 2/6] netns: Teach network device kobjects which namespace they are in.

From: "Serge E. Hallyn" <[email-masked]>
Date: Wed, 5 May 2010 10:17:46 -0500

Quoting Eric W. Biederman ([email-masked]):
> diff --git a/net/Kconfig b/net/Kconfig
> index 041c35e..265e33b 100644
> --- a/net/Kconfig
> +++ b/net/Kconfig
> @@ -45,6 +45,14 @@ config COMPAT_NETLINK_MESSAGES
> 
>  menu "Networking options"
> 
> +config NET_NS
> +	bool "Network namespace support"
> +	default n
> +	depends on EXPERIMENTAL && NAMESPACES
> +	help
> +	  Allow user space to create what appear to be multiple instances
> +	  of the network stack.
> +

Hi Eric,

I'm confused - NET_NS is defined in init/Kconfig right now.  Is the tree
you're working from very different from mine, or is this the unfortunate
rekult of the patches sitting so long?

>  source "net/packet/Kconfig"
>  source "net/unix/Kconfig"
>  source "net/xfrm/Kconfig"
> diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
> index 099c753..1b98e36 100644
> --- a/net/core/net-sysfs.c
> +++ b/net/core/net-sysfs.c
> @@ -13,7 +13,9 @@
>  #include <linux/kernel.h>
>  #include <linux/netdevice.h>
>  #include <linux/if_arp.h>
> +#include <linux/nsproxy.h>
>  #include <net/sock.h>
> +#include <net/net_namespace.h>
>  #include <linux/rtnetlink.h>
>  #include <linux/wireless.h>
>  #include <net/wext.h>
> @@ -466,6 +468,37 @@ static struct attribute_group wireless_group = {
>  };
>  #endif
> 
> +static const void *net_current_ns(void)
> +{
> +	return current->nsproxy->net_ns;
> +}
> +
> +static const void *net_initial_ns(void)
> +{
> +	return &init_net;
> +}
> +
> +static const void *net_netlink_ns(struct sock *sk)
> +{
> +	return sock_net(sk);
> +}
> +
> +static struct kobj_ns_type_operations net_ns_type_operations = {
> +	.type = KOBJ_NS_TYPE_NET,
> +	.current_ns = net_current_ns,
> +	.netlink_ns = net_netlink_ns,
> +	.initial_ns = net_initial_ns,
> +};
> +
> +static void net_kobj_ns_exit(struct net *net)
> +{
> +	kobj_ns_exit(KOBJ_NS_TYPE_NET, net);
> +}
> +
> +static struct pernet_operations sysfs_net_ops = {
> +	.exit = net_kobj_ns_exit,
> +};
> +
>  #endif /* CONFIG_SYSFS */

...

>  int netdev_kobject_init(void)
>  {
> +	kobj_ns_type_register(&net_ns_type_operations);
> +#ifdef CONFIG_SYSFS
> +	register_pernet_subsys(&sysfs_net_ops);
> +#endif
>  	return class_register(&net_class);

I think the kobj_ns_type_register() needs to be under
ifdef CONFIG_SYSFS as well, bc net_ns_type_operations is defined
under ifdef CONFIG_SYSFS.

-serge