From: David S. Miller <davem@davemloft.net>
Date: Thu, 19 Mar 2015 02:52:33 +0000 (-0400)
Subject: net: Fix high overhead of vlan sub-device teardown.
X-Git-Tag: omap-for-v4.1/fixes-rc1~141^2~208
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=99c4a26a159b28fa46a3e746a9b41b297e73d261;p=pandora-kernel.git

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 <noureddine@arista.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

Reading git-diff-tree failed