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>

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index d7b81e4..17923a5 100644 (file)
--- 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);