[PATCH net-next-2.6] vlan: remove one synchronize_net() call
From: Eric Dumazet <hidden>
Date: 2011-05-09 14:40:48
Subsystem:
networking drivers, networking [general], the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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 <redacted> Cc: Ben Greear <redacted> Cc: Patrick McHardy <redacted> Cc: Paul E. McKenney <redacted> Cc: Jesse Gross <redacted> Cc: Michał Mirosław <mirq-linux@rere.qmqm.pl> --- include/linux/if_vlan.h | 1 - net/8021q/vlan.c | 10 ++++------ 2 files changed, 4 insertions(+), 7 deletions(-)
diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
index 546d9d3..290bd8a 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h@@ -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;
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 @@ 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)