[ATM]: Oops reading net/atm/arp

cat /proc/net/atm/arp causes the NULL pointer dereference in the
get_proc_net+0xc/0x3a. This happens as proc_get_net believes that the
parent proc dir entry contains struct net.

Fix this assumption for "net/atm" case.

The problem is introduced by the commit c0097b07abf5f92ab135d024dd41bd2aada1512f
from Eric W. Biederman/Daniel Lezcano.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index a531682..8f92546 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -201,6 +201,8 @@
 extern struct proc_dir_entry *proc_net_fops_create(struct net *net,
 	const char *name, mode_t mode, const struct file_operations *fops);
 extern void proc_net_remove(struct net *net, const char *name);
+extern struct proc_dir_entry *proc_net_mkdir(struct net *net, const char *name,
+	struct proc_dir_entry *parent);
 
 #else