[NET]: fix oops after tunnel module unload

Tunnel modules used to obtain module refcount each time when
some tunnel was created, which meaned that tunnel could be unloaded
only after all the tunnels are deleted.

Since killing old MOD_*_USE_COUNT macros this protection has gone.
It is possible to return it back as module_get/put, but it looks
more natural and practically useful to force destruction of all
the child tunnels on module unload.

Signed-off-by: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 2 deletions

diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index b788f55e139b..e553e5b80d6e 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -195,7 +195,6 @@ static struct ip_tunnel * ipip6_tunnel_locate(struct ip_tunnel_parm *parms, int
         dev_hold(dev);
 
         ipip6_tunnel_link(nt);
-        /* Do not decrement MOD_USE_COUNT here. */
         return nt;
 
 failed:
@@ -794,10 +793,28 @@ static struct net_protocol sit_protocol = {
         .err_handler    =       ipip6_err,
 };
 
+static void __exit sit_destroy_tunnels(void)
+{
+        int prio;
+
+        for (prio = 1; prio < 4; prio++) {
+                int h;
+                for (h = 0; h < HASH_SIZE; h++) {
+                        struct ip_tunnel *t;
+                        while ((t = tunnels[prio][h]) != NULL)
+                                unregister_netdevice(t->dev);
+                }
+        }
+}
+
 void __exit sit_cleanup(void)
 {
         inet_del_protocol(&sit_protocol, IPPROTO_IPV6);
-        unregister_netdev(ipip6_fb_tunnel_dev);
+
+        rtnl_lock();
+        sit_destroy_tunnels();
+        unregister_netdevice(ipip6_fb_tunnel_dev);
+        rtnl_unlock();
 }
 
 int __init sit_init(void)