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-rw-r--r--net/core/dev.c49
1 files changed, 48 insertions, 1 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 5c713f2..65f829c 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5247,10 +5247,12 @@ static int dev_new_index(struct net *net)
/* Delayed registration/unregisteration */
static LIST_HEAD(net_todo_list);
+static DECLARE_WAIT_QUEUE_HEAD(netdev_unregistering_wq);
static void net_set_todo(struct net_device *dev)
{
list_add_tail(&dev->todo_list, &net_todo_list);
+ dev_net(dev)->dev_unreg_count++;
}
static void rollback_registered_many(struct list_head *head)
@@ -5918,6 +5920,12 @@ void netdev_run_todo(void)
if (dev->destructor)
dev->destructor(dev);
+ /* Report a network device has been unregistered */
+ rtnl_lock();
+ dev_net(dev)->dev_unreg_count--;
+ __rtnl_unlock();
+ wake_up(&netdev_unregistering_wq);
+
/* Free network device */
kobject_put(&dev->dev.kobj);
}
@@ -6603,6 +6611,34 @@ static void __net_exit default_device_exit(struct net *net)
rtnl_unlock();
}
+static void __net_exit rtnl_lock_unregistering(struct list_head *net_list)
+{
+ /* Return with the rtnl_lock held when there are no network
+ * devices unregistering in any network namespace in net_list.
+ */
+ struct net *net;
+ bool unregistering;
+ DEFINE_WAIT(wait);
+
+ for (;;) {
+ prepare_to_wait(&netdev_unregistering_wq, &wait,
+ TASK_UNINTERRUPTIBLE);
+ unregistering = false;
+ rtnl_lock();
+ list_for_each_entry(net, net_list, exit_list) {
+ if (net->dev_unreg_count > 0) {
+ unregistering = true;
+ break;
+ }
+ }
+ if (!unregistering)
+ break;
+ __rtnl_unlock();
+ schedule();
+ }
+ finish_wait(&netdev_unregistering_wq, &wait);
+}
+
static void __net_exit default_device_exit_batch(struct list_head *net_list)
{
/* At exit all network devices most be removed from a network
@@ -6614,7 +6650,18 @@ static void __net_exit default_device_exit_batch(struct list_head *net_list)
struct net *net;
LIST_HEAD(dev_kill_list);
- rtnl_lock();
+ /* To prevent network device cleanup code from dereferencing
+ * loopback devices or network devices that have been freed
+ * wait here for all pending unregistrations to complete,
+ * before unregistring the loopback device and allowing the
+ * network namespace be freed.
+ *
+ * The netdev todo list containing all network devices
+ * unregistrations that happen in default_device_exit_batch
+ * will run in the rtnl_unlock() at the end of
+ * default_device_exit_batch.
+ */
+ rtnl_lock_unregistering(net_list);
list_for_each_entry(net, net_list, exit_list) {
for_each_netdev_reverse(net, dev) {
if (dev->rtnl_link_ops)
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