xen/netloop: make netloop permanent

with reference to RH BZ#567540 [0], this patch makes the netloop
module permanent (like netback is currently). It reverts parts of
xen-unstable c/s 9019:271cb04a4f2b [1] [2] (though that has a typo:
"__init clean_loopback", so it was probably changed later too).

The patch fixes the problem of "rmmod netloop" hanging, resulting in
blocked tasks and inability to shut down cleanly:

... kernel: unregister_netdevice: waiting for veth4 to become
free. Usage count = 1

The problem was also reported for Debian [3] and on the Fedora-xen
mailing list [4].

[0] https://bugzilla.redhat.com/show_bug.cgi?id=567540
[1] http://lists.xensource.com/archives/html/xen-devel/2006-02/msg01033.html
[2] http://xenbits.xensource.com/xen-unstable.hg?rev/271cb04a4f2b
[3] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=425703
[4] http://www.redhat.com/archives/fedora-xen/2007-April/msg00074.html

From: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Keir Fraser <keir@xen.org>

diff --git a/drivers/xen/netback/loopback.c b/drivers/xen/netback/loopback.c
index 9d1839ab7d2d6bca3121f001638b2106ff993f04..239ac128012e58782a358b5755857a8a901f88a7 100644 (file)
--- a/drivers/xen/netback/loopback.c
+++ b/drivers/xen/netback/loopback.c
@@ -290,23 +290,6 @@ static int __init make_loopback(int i)
        return err;
 }
 
-static void __exit clean_loopback(int i)
-{
-       struct net_device *dev1, *dev2;
-       char dev_name[IFNAMSIZ];
-
-       sprintf(dev_name, "vif0.%d", i);
-       dev1 = dev_get_by_name(dev_name);
-       sprintf(dev_name, "veth%d", i);
-       dev2 = dev_get_by_name(dev_name);
-       if (dev1 && dev2) {
-               unregister_netdev(dev2);
-               unregister_netdev(dev1);
-               free_netdev(dev2);
-               free_netdev(dev1);
-       }
-}
-
 static int __init loopback_init(void)
 {
        int i, err = 0;
@@ -323,14 +306,4 @@ static int __init loopback_init(void)
 
 module_init(loopback_init);
 
-static void __exit loopback_exit(void)
-{
-       int i;
-
-       for (i = nloopbacks; i-- > 0; )
-               clean_loopback(i);
-}
-
-module_exit(loopback_exit);
-
 MODULE_LICENSE("Dual BSD/GPL");