1 files changed, 71 insertions, 16 deletions

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 25689e9df3b..1b7082d08f3 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -51,15 +51,13 @@ static struct proto macvtap_proto = {
 };
 
 /*
- * Minor number matches netdev->ifindex, so need a potentially
- * large value. This also makes it possible to split the
- * tap functionality out again in the future by offering it
- * from other drivers besides macvtap. As long as every device
- * only has one tap, the interface numbers assure that the
- * device nodes are unique.
+ * Variables for dealing with macvtaps device numbers.
  */
 static dev_t macvtap_major;
-#define MACVTAP_NUM_DEVS 65536
+#define MACVTAP_NUM_DEVS (1U << MINORBITS)
+static DEFINE_MUTEX(minor_lock);
+static DEFINE_IDR(minor_idr);
+
 #define GOODCOPY_LEN 128
 static struct class *macvtap_class;
 static struct cdev macvtap_cdev;
@@ -275,6 +273,58 @@ static int macvtap_receive(struct sk_buff *skb)
 	return macvtap_forward(skb->dev, skb);
 }
 
+static int macvtap_get_minor(struct macvlan_dev *vlan)
+{
+	int retval = -ENOMEM;
+	int id;
+
+	mutex_lock(&minor_lock);
+	if (idr_pre_get(&minor_idr, GFP_KERNEL) == 0)
+		goto exit;
+
+	retval = idr_get_new_above(&minor_idr, vlan, 1, &id);
+	if (retval < 0) {
+		if (retval == -EAGAIN)
+			retval = -ENOMEM;
+		goto exit;
+	}
+	if (id < MACVTAP_NUM_DEVS) {
+		vlan->minor = id;
+	} else {
+		printk(KERN_ERR "too many macvtap devices\n");
+		retval = -EINVAL;
+		idr_remove(&minor_idr, id);
+	}
+exit:
+	mutex_unlock(&minor_lock);
+	return retval;
+}
+
+static void macvtap_free_minor(struct macvlan_dev *vlan)
+{
+	mutex_lock(&minor_lock);
+	if (vlan->minor) {
+		idr_remove(&minor_idr, vlan->minor);
+		vlan->minor = 0;
+	}
+	mutex_unlock(&minor_lock);
+}
+
+static struct net_device *dev_get_by_macvtap_minor(int minor)
+{
+	struct net_device *dev = NULL;
+	struct macvlan_dev *vlan;
+
+	mutex_lock(&minor_lock);
+	vlan = idr_find(&minor_idr, minor);
+	if (vlan) {
+		dev = vlan->dev;
+		dev_hold(dev);
+	}
+	mutex_unlock(&minor_lock);
+	return dev;
+}
+
 static int macvtap_newlink(struct net *src_net,
 			   struct net_device *dev,
 			   struct nlattr *tb[],
@@ -329,7 +379,7 @@ static void macvtap_sock_destruct(struct sock *sk)
 static int macvtap_open(struct inode *inode, struct file *file)
 {
 	struct net *net = current->nsproxy->net_ns;
-	struct net_device *dev = dev_get_by_index(net, iminor(inode));
+	struct net_device *dev = dev_get_by_macvtap_minor(iminor(inode));
 	struct macvtap_queue *q;
 	int err;
 
@@ -337,11 +387,6 @@ static int macvtap_open(struct inode *inode, struct file *file)
 	if (!dev)
 		goto out;
 
-	/* check if this is a macvtap device */
-	err = -EINVAL;
-	if (dev->rtnl_link_ops != &macvtap_link_ops)
-		goto out;
-
 	err = -ENOMEM;
 	q = (struct macvtap_queue *)sk_alloc(net, AF_UNSPEC, GFP_KERNEL,
 					     &macvtap_proto);
@@ -961,12 +1006,15 @@ static int macvtap_device_event(struct notifier_block *unused,
 				unsigned long event, void *ptr)
 {
 	struct net_device *dev = ptr;
+	struct macvlan_dev *vlan;
 	struct device *classdev;
 	dev_t devt;
+	int err;
 
 	if (dev->rtnl_link_ops != &macvtap_link_ops)
 		return NOTIFY_DONE;
 
+	vlan = netdev_priv(dev);
 
 	switch (event) {
 	case NETDEV_REGISTER:
@@ -974,15 +1022,22 @@ static int macvtap_device_event(struct notifier_block *unused,
 		 * been registered but before register_netdevice has
 		 * finished running.
 		 */
-		devt = MKDEV(MAJOR(macvtap_major), dev->ifindex);
+		err = macvtap_get_minor(vlan);
+		if (err)
+			return notifier_from_errno(err);
+
+		devt = MKDEV(MAJOR(macvtap_major), vlan->minor);
 		classdev = device_create(macvtap_class, &dev->dev, devt,
 					 dev, "tap%d", dev->ifindex);
-		if (IS_ERR(classdev))
+		if (IS_ERR(classdev)) {
+			macvtap_free_minor(vlan);
 			return notifier_from_errno(PTR_ERR(classdev));
+		}
 		break;
 	case NETDEV_UNREGISTER:
-		devt = MKDEV(MAJOR(macvtap_major), dev->ifindex);
+		devt = MKDEV(MAJOR(macvtap_major), vlan->minor);
 		device_destroy(macvtap_class, devt);
+		macvtap_free_minor(vlan);
 		break;
 	}