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Commit 48752e1b authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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vlan: remove one synchronize_net() call 



At VLAN dismantle phase, unregister_vlan_dev() makes one
synchronize_net() call after vlan_group_set_device(grp, vlan_id, NULL).

This call can be safely removed because we are calling
unregister_netdevice_queue() to queue device for deletion, and this
process needs at least one rcu grace period to complete.

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Cc: Ben Greear <greearb@candelatech.com>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Jesse Gross <jesse@nicira.com>
Cc: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Acked-by: default avatarJesse Gross <jesse@nicira.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent da37e368

include/linux/if_vlan.h

+0 −1
Original line number Diff line number Diff line
@@ -86,7 +86,6 @@ struct vlan_group { 
					    * the vlan is attached to.

					    */

	unsigned int		nr_vlans;

	int			killall;

	struct hlist_node	hlist;	/* linked list */

	struct net_device **vlan_devices_arrays[VLAN_GROUP_ARRAY_SPLIT_PARTS];

	struct rcu_head		rcu;

net/8021q/vlan.c

+4 −6
Original line number Diff line number Diff line
@@ -120,9 +120,10 @@ void unregister_vlan_dev(struct net_device *dev, struct list_head *head) 
	grp->nr_vlans--;



	vlan_group_set_device(grp, vlan_id, NULL);

	if (!grp->killall)

		synchronize_net();



	/* Because unregister_netdevice_queue() makes sure at least one rcu

	 * grace period is respected before device freeing,

	 * we dont need to call synchronize_net() here.

	 */

	unregister_netdevice_queue(dev, head);



	/* If the group is now empty, kill off the group. */
@@ -478,9 +479,6 @@ static int vlan_device_event(struct notifier_block *unused, unsigned long event, 
		if (dev->reg_state != NETREG_UNREGISTERING)

			break;



		/* Delete all VLANs for this dev. */

		grp->killall = 1;



		for (i = 0; i < VLAN_N_VID; i++) {

			vlandev = vlan_group_get_device(grp, i);

			if (!vlandev)