[NET]: Make /proc/net per network namespace

This patch makes /proc/net per network namespace.  It modifies the global
variables proc_net and proc_net_stat to be per network namespace.
The proc_net file helpers are modified to take a network namespace argument,
and all of their callers are fixed to pass &init_net for that argument.
This ensures that all of the /proc/net files are only visible and
usable in the initial network namespace until the code behind them
has been updated to be handle multiple network namespaces.

Making /proc/net per namespace is necessary as at least some files
in /proc/net depend upon the set of network devices which is per
network namespace, and even more files in /proc/net have contents
that are relevant to a single network namespace.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/pppoe.c

@@ -78,6 +78,7 @@
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
 
+#include <net/net_namespace.h>
 #include <net/sock.h>
 
 #include <asm/uaccess.h>
@@ -1042,7 +1043,7 @@ static int __init pppoe_proc_init(void)
 {
 	struct proc_dir_entry *p;
 
-	p = create_proc_entry("net/pppoe", S_IRUGO, NULL);
+	p = create_proc_entry("pppoe", S_IRUGO, init_net.proc_net);
 	if (!p)
 		return -ENOMEM;
 
@@ -1113,7 +1114,7 @@ static void __exit pppoe_exit(void)
 	dev_remove_pack(&pppoes_ptype);
 	dev_remove_pack(&pppoed_ptype);
 	unregister_netdevice_notifier(&pppoe_notifier);
-	remove_proc_entry("net/pppoe", NULL);
+	remove_proc_entry("pppoe", init_net.proc_net);
 	proto_unregister(&pppoe_sk_proto);
 }