From 99c4a26a159b28fa46a3e746a9b41b297e73d261 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Wed, 18 Mar 2015 22:52:33 -0400 Subject: [PATCH] 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 --- include/linux/netdevice.h | 1 + net/8021q/vlan.c | 16 +++++++++++++--- net/core/dev.c | 10 ++++++---- 3 files changed, 20 insertions(+), 7 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index ec8f9b5f6500..76951c5fbedf 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2156,6 +2156,7 @@ struct net_device *__dev_get_by_name(struct net *net, const char *name); int dev_alloc_name(struct net_device *dev, const char *name); int dev_open(struct net_device *dev); int dev_close(struct net_device *dev); +int dev_close_many(struct list_head *head, bool unlink); void dev_disable_lro(struct net_device *dev); int dev_loopback_xmit(struct sk_buff *newskb); int dev_queue_xmit(struct sk_buff *skb); diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c index 64c6bed4a3d3..98a30a5b8664 100644 --- a/net/8021q/vlan.c +++ b/net/8021q/vlan.c @@ -413,7 +413,10 @@ static int vlan_device_event(struct notifier_block *unused, unsigned long event, vlan_transfer_features(dev, vlandev); break; - case NETDEV_DOWN: + case NETDEV_DOWN: { + struct net_device *tmp; + LIST_HEAD(close_list); + if (dev->features & NETIF_F_HW_VLAN_CTAG_FILTER) vlan_vid_del(dev, htons(ETH_P_8021Q), 0); @@ -425,11 +428,18 @@ static int vlan_device_event(struct notifier_block *unused, unsigned long event, vlan = vlan_dev_priv(vlandev); if (!(vlan->flags & VLAN_FLAG_LOOSE_BINDING)) - dev_change_flags(vlandev, flgs & ~IFF_UP); + list_add(&vlandev->close_list, &close_list); + } + + dev_close_many(&close_list, false); + + list_for_each_entry_safe(vlandev, tmp, &close_list, close_list) { netif_stacked_transfer_operstate(dev, vlandev); + list_del_init(&vlandev->close_list); } + list_del(&close_list); break; - + } case NETDEV_UP: /* Put all VLANs for this dev in the up state too. */ vlan_group_for_each_dev(grp, i, vlandev) { 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. */ -- 2.20.1