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>
diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c
index 969e700..718d635d 100644
--- a/net/8021q/vlan.c
+++ b/net/8021q/vlan.c
@@ -120,9 +120,10 @@
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 @@
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)