vlan: remove one synchronize_net() call (48752e1b) · Commits · 戴 / test

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>

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)

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