tun: Remove unnecessary tun_get_by_name

Currently the tun driver keeps a private list of tun devices for what
appears to be a small gain in performance when reconnecting a file
descriptor to an existing tun or tap device.  So simplify the code by
removing it.

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

1 files changed, 19 insertions, 55 deletions

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index d7b81e4fdd56..17923a508535 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -88,7 +88,6 @@ struct tap_filter {
 };
 
 struct tun_struct {
-        struct list_head        list;
         unsigned int            flags;
         int                     attached;
         uid_t                   owner;
@@ -213,11 +212,6 @@ static int check_filter(struct tap_filter *filter, const struct sk_buff *skb)
 
 /* Network device part of the driver */
 
-static int tun_net_id;
-struct tun_net {
-        struct list_head dev_list;
-};
-
 static const struct ethtool_ops tun_ethtool_ops;
 
 /* Net device open. */
@@ -697,30 +691,22 @@ static void tun_setup(struct net_device *dev)
         dev->features |= NETIF_F_NETNS_LOCAL;
 }
 
-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, &tn->dev_list, list) {
-                if (!strncmp(tun->dev->name, name, IFNAMSIZ))
-                    return tun;
-        }
-
-        return NULL;
-}
-
 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;
         const struct cred *cred = current_cred();
         int err;
 
-        tn = net_generic(net, tun_net_id);
-        tun = tun_get_by_name(tn, ifr->ifr_name);
-        if (tun) {
+        dev = __dev_get_by_name(net, ifr->ifr_name);
+        if (dev) {
+                if ((ifr->ifr_flags & IFF_TUN) && dev->netdev_ops == &tun_netdev_ops)
+                        tun = netdev_priv(dev);
+                else if ((ifr->ifr_flags & IFF_TAP) && dev->netdev_ops == &tap_netdev_ops)
+                        tun = netdev_priv(dev);
+                else
+                        return -EINVAL;
+
                 if (tun->attached)
                         return -EBUSY;
 
@@ -733,8 +719,6 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
                         return -EPERM;
                 }
         }
-        else if (__dev_get_by_name(net, ifr->ifr_name))
-                return -EINVAL;
         else {
                 char *name;
                 unsigned long flags = 0;
@@ -782,8 +766,6 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
                 err = register_netdevice(tun->dev);
                 if (err < 0)
                         goto err_free_dev;
-
-                list_add(&tun->list, &tn->dev_list);
         }
 
         DBG(KERN_INFO "%s: tun_set_iff\n", tun->dev->name);
@@ -1095,10 +1077,8 @@ static int tun_chr_close(struct inode *inode, struct file *file)
         /* Drop read queue */
         skb_queue_purge(&tun->readq);
 
-        if (!(tun->flags & TUN_PERSIST)) {
-                list_del(&tun->list);
+        if (!(tun->flags & TUN_PERSIST))
                 unregister_netdevice(tun->dev);
-        }
 
         rtnl_unlock();
 
@@ -1212,37 +1192,21 @@ static const struct ethtool_ops tun_ethtool_ops = {
 
 static int tun_init_net(struct net *net)
 {
-        struct tun_net *tn;
-
-        tn = kmalloc(sizeof(*tn), GFP_KERNEL);
-        if (tn == NULL)
-                return -ENOMEM;
-
-        INIT_LIST_HEAD(&tn->dev_list);
-
-        if (net_assign_generic(net, tun_net_id, tn)) {
-                kfree(tn);
-                return -ENOMEM;
-        }
-
         return 0;
 }
 
 static void tun_exit_net(struct net *net)
 {
-        struct tun_net *tn;
-        struct tun_struct *tun, *nxt;
-
-        tn = net_generic(net, tun_net_id);
+        struct net_device *dev, *next;
 
         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);
+        for_each_netdev_safe(net, dev, next) {
+                if (dev->ethtool_ops != &tun_ethtool_ops)
+                        continue;
+                DBG(KERN_INFO "%s cleaned up\n", dev->name);
+                unregister_netdevice(dev);
         }
         rtnl_unlock();
-
-        kfree(tn);
 }
 
 static struct pernet_operations tun_net_ops = {
@@ -1257,7 +1221,7 @@ static int __init tun_init(void)
         printk(KERN_INFO "tun: %s, %s\n", DRV_DESCRIPTION, DRV_VERSION);
         printk(KERN_INFO "tun: %s\n", DRV_COPYRIGHT);
 
-        ret = register_pernet_gen_device(&tun_net_id, &tun_net_ops);
+        ret = register_pernet_device(&tun_net_ops);
         if (ret) {
                 printk(KERN_ERR "tun: Can't register pernet ops\n");
                 goto err_pernet;
@@ -1271,7 +1235,7 @@ static int __init tun_init(void)
         return 0;
 
 err_misc:
-        unregister_pernet_gen_device(tun_net_id, &tun_net_ops);
+        unregister_pernet_device(&tun_net_ops);
 err_pernet:
         return ret;
 }
@@ -1279,7 +1243,7 @@ err_pernet:
 static void tun_cleanup(void)
 {
         misc_deregister(&tun_miscdev);
-        unregister_pernet_gen_device(tun_net_id, &tun_net_ops);
+        unregister_pernet_device(&tun_net_ops);
 }
 
 module_init(tun_init);