macvtap: convert to idr_alloc()

Convert to the much saner new idr interface.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/net/macvtap.c

@@ -279,28 +279,17 @@ static int macvtap_receive(struct sk_buff *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 {
+	retval = idr_alloc(&minor_idr, vlan, 1, MACVTAP_NUM_DEVS, GFP_KERNEL);
+	if (retval >= 0) {
+		vlan->minor = retval;
+	} else if (retval == -ENOSPC) {
 		printk(KERN_ERR "too many macvtap devices\n");
 		retval = -EINVAL;
-		idr_remove(&minor_idr, id);
 	}
-exit:
 	mutex_unlock(&minor_lock);
-	return retval;
+	return retval < 0 ? retval : 0;
 }
 
 static void macvtap_free_minor(struct macvlan_dev *vlan)