From 99c4a26a159b28fa46a3e746a9b41b297e73d261 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Wed, 18 Mar 2015 22:52:33 -0400 Subject: net: Fix high overhead of vlan sub-device teardown. When a networking device is taken down that has a non-trivial number of VLAN devices configured under it, we eat a full synchronize_net() for every such VLAN device. This is because of the call chain: NETDEV_DOWN notifier --> vlan_device_event() --> dev_change_flags() --> __dev_change_flags() --> __dev_close() --> __dev_close_many() --> dev_deactivate_many() --> synchronize_net() This is kind of rediculous because we already have infrastructure for batching doing operation X to a list of net devices so that we only incur one sync. So make use of that by exporting dev_close_many() and adjusting it's interfaace so that the caller can fully manage the batch list. Use this in vlan_device_event() and all the overhead goes away. Reported-by: Salam Noureddine Signed-off-by: David S. Miller --- net/core/dev.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'net/core') diff --git a/net/core/dev.c b/net/core/dev.c index a1f24151db5b..5d43e010ef87 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -1385,7 +1385,7 @@ static int __dev_close(struct net_device *dev) return retval; } -static int dev_close_many(struct list_head *head) +int dev_close_many(struct list_head *head, bool unlink) { struct net_device *dev, *tmp; @@ -1399,11 +1399,13 @@ static int dev_close_many(struct list_head *head) list_for_each_entry_safe(dev, tmp, head, close_list) { rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING, GFP_KERNEL); call_netdevice_notifiers(NETDEV_DOWN, dev); - list_del_init(&dev->close_list); + if (unlink) + list_del_init(&dev->close_list); } return 0; } +EXPORT_SYMBOL(dev_close_many); /** * dev_close - shutdown an interface. @@ -1420,7 +1422,7 @@ int dev_close(struct net_device *dev) LIST_HEAD(single); list_add(&dev->close_list, &single); - dev_close_many(&single); + dev_close_many(&single, true); list_del(&single); } return 0; @@ -5986,7 +5988,7 @@ static void rollback_registered_many(struct list_head *head) /* If device is running, close it first. */ list_for_each_entry(dev, head, unreg_list) list_add_tail(&dev->close_list, &close_head); - dev_close_many(&close_head); + dev_close_many(&close_head, true); list_for_each_entry(dev, head, unreg_list) { /* And unlink it from device chain. */ -- cgit v1.2.3