rtnetlink: wait for unregistering devices in rtnl_link_unregister()
From: Cong Wang <cwang@twopensource.com>
commit 50624c934db18ab90 (net: Delay default_device_exit_batch until no
devices are unregistering) introduced rtnl_lock_unregistering() for
default_device_exit_batch(). Same race could happen we when rmmod a driver
which calls rtnl_link_unregister() as we call dev->destructor without rtnl
lock.
For long term, I think we should clean up the mess of netdev_run_todo()
and net namespce exit code.
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Cong Wang <cwang@twopensource.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 9837beb..2d8d8fc 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -353,15 +353,46 @@
}
EXPORT_SYMBOL_GPL(__rtnl_link_unregister);
+/* Return with the rtnl_lock held when there are no network
+ * devices unregistering in any network namespace.
+ */
+static void rtnl_lock_unregistering_all(void)
+{
+ struct net *net;
+ bool unregistering;
+ DEFINE_WAIT(wait);
+
+ for (;;) {
+ prepare_to_wait(&netdev_unregistering_wq, &wait,
+ TASK_UNINTERRUPTIBLE);
+ unregistering = false;
+ rtnl_lock();
+ for_each_net(net) {
+ if (net->dev_unreg_count > 0) {
+ unregistering = true;
+ break;
+ }
+ }
+ if (!unregistering)
+ break;
+ __rtnl_unlock();
+ schedule();
+ }
+ finish_wait(&netdev_unregistering_wq, &wait);
+}
+
/**
* rtnl_link_unregister - Unregister rtnl_link_ops from rtnetlink.
* @ops: struct rtnl_link_ops * to unregister
*/
void rtnl_link_unregister(struct rtnl_link_ops *ops)
{
- rtnl_lock();
+ /* Close the race with cleanup_net() */
+ mutex_lock(&net_mutex);
+ rtnl_lock_unregistering_all();
__rtnl_link_unregister(ops);
rtnl_unlock();
+ mutex_unlock(&net_mutex);
}
EXPORT_SYMBOL_GPL(rtnl_link_unregister);