[TUN]: Make the tun_dev_list per-net.

Remove the static tun_dev_list and replace its occurrences in
driver with per-net one.

It is used in two places - in tun_set_iff and tun_cleanup. In 
the first case it's legal to use current net_ns. In the cleanup
call - move the loop, that unregisters all devices in net exit
hook.
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/tun.c

@@ -62,6 +62,7 @@
 #include <linux/if_ether.h>
 #include <linux/if_tun.h>
 #include <linux/crc32.h>
+#include <linux/nsproxy.h>
 #include <net/net_namespace.h>
 #include <net/netns/generic.h>
 
@@ -112,7 +113,6 @@ struct tun_net {
 	struct list_head dev_list;
 };
 
-static LIST_HEAD(tun_dev_list);
 static const struct ethtool_ops tun_ethtool_ops;
 
 /* Net device open. */
@@ -479,12 +479,12 @@ static void tun_setup(struct net_device *dev)
 	dev->destructor = free_netdev;
 }
 
-static struct tun_struct *tun_get_by_name(const char *name)
+static struct tun_struct *tun_get_by_name(struct tun_net *tn, const char *name)
 {
 	struct tun_struct *tun;
 
 	ASSERT_RTNL();
-	list_for_each_entry(tun, &tun_dev_list, list) {
+	list_for_each_entry(tun, &tn->dev_list, list) {
 		if (!strncmp(tun->dev->name, name, IFNAMSIZ))
 		    return tun;
 	}
@@ -492,13 +492,15 @@ static struct tun_struct *tun_get_by_name(const char *name)
 	return NULL;
 }
 
-static int tun_set_iff(struct file *file, struct ifreq *ifr)
+static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
 {
+	struct tun_net *tn;
 	struct tun_struct *tun;
 	struct net_device *dev;
 	int err;
 
-	tun = tun_get_by_name(ifr->ifr_name);
+	tn = net_generic(net, tun_net_id);
+	tun = tun_get_by_name(tn, ifr->ifr_name);
 	if (tun) {
 		if (tun->attached)
 			return -EBUSY;
@@ -511,7 +513,7 @@ static int tun_set_iff(struct file *file, struct ifreq *ifr)
 		     !capable(CAP_NET_ADMIN))
 			return -EPERM;
 	}
-	else if (__dev_get_by_name(&init_net, ifr->ifr_name))
+	else if (__dev_get_by_name(net, ifr->ifr_name))
 		return -EINVAL;
 	else {
 		char *name;
@@ -564,7 +566,7 @@ static int tun_set_iff(struct file *file, struct ifreq *ifr)
 		if (err < 0)
 			goto err_free_dev;
 
-		list_add(&tun->list, &tun_dev_list);
+		list_add(&tun->list, &tn->dev_list);
 	}
 
 	DBG(KERN_INFO "%s: tun_set_iff\n", tun->dev->name);
@@ -609,7 +611,7 @@ static int tun_chr_ioctl(struct inode *inode, struct file *file,
 		ifr.ifr_name[IFNAMSIZ-1] = '\0';
 
 		rtnl_lock();
-		err = tun_set_iff(file, &ifr);
+		err = tun_set_iff(current->nsproxy->net_ns, file, &ifr);
 		rtnl_unlock();
 
 		if (err)
@@ -936,8 +938,17 @@ static int tun_init_net(struct net *net)
 static void tun_exit_net(struct net *net)
 {
 	struct tun_net *tn;
+	struct tun_struct *tun, *nxt;
 
 	tn = net_generic(net, tun_net_id);
+
+	rtnl_lock();
+	list_for_each_entry_safe(tun, nxt, &tn->dev_list, list) {
+		DBG(KERN_INFO "%s cleaned up\n", tun->dev->name);
+		unregister_netdevice(tun->dev);
+	}
+	rtnl_unlock();
+
 	kfree(tn);
 }
 
@@ -974,17 +985,7 @@ static int __init tun_init(void)
 
 static void tun_cleanup(void)
 {
-	struct tun_struct *tun, *nxt;
-
 	misc_deregister(&tun_miscdev);
-
-	rtnl_lock();
-	list_for_each_entry_safe(tun, nxt, &tun_dev_list, list) {
-		DBG(KERN_INFO "%s cleaned up\n", tun->dev->name);
-		unregister_netdevice(tun->dev);
-	}
-	rtnl_unlock();
-
 	unregister_pernet_gen_device(tun_net_id, &tun_net_ops);
 }