tun: fix carrier on/off status

Commit c8d68e6be1c3b242f1c598595830890b65cea64a removed carrier off call
from tun_detach since it's now called on queue disable and not only on
tun close.  This confuses userspace which used this flag to detect a
free tun. To fix, put this back but under if (clean).

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Jason Wang <jasowang@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Tested-by: Toralf Förster <toralf.foerster@gmx.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 5 deletions

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index cc09b67c23bc..ffdb84474c47 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -439,10 +439,13 @@ static void __tun_detach(struct tun_file *tfile, bool clean)
         }
 
         if (clean) {
-                if (tun && tun->numqueues == 0 && tun->numdisabled == 0 &&
-                    !(tun->flags & TUN_PERSIST))
-                        if (tun->dev->reg_state == NETREG_REGISTERED)
+                if (tun && tun->numqueues == 0 && tun->numdisabled == 0) {
+                        netif_carrier_off(tun->dev);
+
+                        if (!(tun->flags & TUN_PERSIST) &&
+                            tun->dev->reg_state == NETREG_REGISTERED)
                                 unregister_netdevice(tun->dev);
+                }
 
                 BUG_ON(!test_bit(SOCK_EXTERNALLY_ALLOCATED,
                                  &tfile->socket.flags));
@@ -1658,10 +1661,10 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
                     device_create_file(&tun->dev->dev, &dev_attr_owner) ||
                     device_create_file(&tun->dev->dev, &dev_attr_group))
                         pr_err("Failed to create tun sysfs files\n");
-
-                netif_carrier_on(tun->dev);
         }
 
+        netif_carrier_on(tun->dev);
+
         tun_debug(KERN_INFO, tun, "tun_set_iff\n");
 
         if (ifr->ifr_flags & IFF_NO_PI)