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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: Eric 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: Jesse Gross <jesse@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2011-05-09 04:40:44 +00:00 committed by David S. Miller
parent da37e36876
commit 48752e1b18
2 changed files with 4 additions and 7 deletions
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1
include/linux/if_vlan.h
View File

@ -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;

10
net/8021q/vlan.c
View File

@ -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)