net: NETDEV_UNREGISTER_PERNET -> NETDEV_UNREGISTER_BATCH

The motivation for an additional notifier in batched netdevice
notification (rt_do_flush) only needs to be called once per batch not
once per namespace.

For further batching improvements I need a guarantee that the
netdevices are unregistered in order allowing me to unregister an all
of the network devices in a network namespace at the same time with
the guarantee that the loopback device is really and truly
unregistered last.

Additionally it appears that we moved the route cache flush after
the final synchronize_net, which seems wrong and there was no
explanation.  So I have restored the original location of the final
synchronize_net.

Cc: Octavian Purdila <opurdila@ixiacom.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 18 insertions, 28 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 5d131c2f84c..bb37ee1e090 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1353,7 +1353,7 @@ rollback:
 				nb->notifier_call(nb, NETDEV_DOWN, dev);
 			}
 			nb->notifier_call(nb, NETDEV_UNREGISTER, dev);
-			nb->notifier_call(nb, NETDEV_UNREGISTER_PERNET, dev);
+			nb->notifier_call(nb, NETDEV_UNREGISTER_BATCH, dev);
 		}
 	}
 
@@ -4771,8 +4771,7 @@ static void net_set_todo(struct net_device *dev)
 
 static void rollback_registered_many(struct list_head *head)
 {
-	struct net_device *dev, *aux, *fdev;
-	LIST_HEAD(pernet_list);
+	struct net_device *dev;
 
 	BUG_ON(dev_boot_phase);
 	ASSERT_RTNL();
@@ -4828,26 +4827,14 @@ static void rollback_registered_many(struct list_head *head)
 		netdev_unregister_kobject(dev);
 	}
 
-	synchronize_net();
+	/* Process any work delayed until the end of the batch */
+	dev = list_entry(head->next, struct net_device, unreg_list);
+	call_netdevice_notifiers(NETDEV_UNREGISTER_BATCH, dev);
 
-	list_for_each_entry_safe(dev, aux, head, unreg_list) {
-		int new_net = 1;
-		list_for_each_entry(fdev, &pernet_list, unreg_list) {
-			if (net_eq(dev_net(dev), dev_net(fdev))) {
-				new_net = 0;
-				dev_put(dev);
-				break;
-			}
-		}
-		if (new_net)
-			list_move(&dev->unreg_list, &pernet_list);
-	}
+	synchronize_net();
 
-	list_for_each_entry_safe(dev, aux, &pernet_list, unreg_list) {
-		call_netdevice_notifiers(NETDEV_UNREGISTER_PERNET, dev);
-		list_move(&dev->unreg_list, head);
+	list_for_each_entry(dev, head, unreg_list)
 		dev_put(dev);
-	}
 }
 
 static void rollback_registered(struct net_device *dev)
@@ -5129,7 +5116,7 @@ static void netdev_wait_allrefs(struct net_device *dev)
 
 			/* Rebroadcast unregister notification */
 			call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
-			/* don't resend NETDEV_UNREGISTER_PERNET, _PERNET users
+			/* don't resend NETDEV_UNREGISTER_BATCH, _BATCH users
 			 * should have already handle it the first time */
 
 			if (test_bit(__LINK_STATE_LINKWATCH_PENDING,
@@ -5442,11 +5429,6 @@ EXPORT_SYMBOL(unregister_netdevice_queue);
 /**
  *	unregister_netdevice_many - unregister many devices
  *	@head: list of devices
- *
- *	WARNING: Calling this modifies the given list
- *	(in rollback_registered_many). It may change the order of the elements
- *	in the list. However, you can assume it does not add or delete elements
- *	to/from the list.
  */
 void unregister_netdevice_many(struct list_head *head)
 {
@@ -5555,7 +5537,7 @@ int dev_change_net_namespace(struct net_device *dev, struct net *net, const char
 	   this device. They should clean all the things.
 	*/
 	call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
-	call_netdevice_notifiers(NETDEV_UNREGISTER_PERNET, dev);
+	call_netdevice_notifiers(NETDEV_UNREGISTER_BATCH, dev);
 
 	/*
 	 *	Flush the unicast and multicast chains
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 6c1e56aef1f..3b373a8b047 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -959,9 +959,11 @@ static int fib_netdev_event(struct notifier_block *this, unsigned long event, vo
 		break;
 	case NETDEV_CHANGEMTU:
 	case NETDEV_CHANGE:
-	case NETDEV_UNREGISTER_PERNET:
 		rt_cache_flush(dev_net(dev), 0);
 		break;
+	case NETDEV_UNREGISTER_BATCH:
+		rt_cache_flush_batch();
+		break;
 	}
 	return NOTIFY_DONE;
 }
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 9889fbd9648..90cdcfc3293 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -900,6 +900,12 @@ void rt_cache_flush(struct net *net, int delay)
 		rt_do_flush(!in_softirq());
 }
 
+/* Flush previous cache invalidated entries from the cache */
+void rt_cache_flush_batch(void)
+{
+	rt_do_flush(!in_softirq());
+}
+
 /*
  * We change rt_genid and let gc do the cleanup
  */