Subject: Re: [PATCH 1/5] 8021q: Vlan driver should use rcu_barrier() on unload instead of syncronize_net()

From: "Paul E. McKenney" <[email-masked]>
Date: Mon, 8 Jun 2009 08:54:46 -0700

On Mon, Jun 08, 2009 at 03:11:28PM +0200, Jesper Dangaard Brouer wrote:
> The VLAN 8021q driver needs to call rcu_barrier() when unloading the module,
> instead of syncronize_net().  This is needed to make sure that outstanding
> call_rcu() callbacks have completed, before the callback function code is
> removed on module unload.

Looks good!  And thank you for checking up on this!!!

Reviewed-by: Paul E. McKenney <[email-masked]>

> Signed-off-by: Jesper Dangaard Brouer <[email-masked]>
> ---
> 
>  net/8021q/vlan.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c
> index 714e1c3..fe64908 100644
> --- a/net/8021q/vlan.c
> +++ b/net/8021q/vlan.c
> @@ -758,7 +758,7 @@ static void __exit vlan_cleanup_module(void)
>  		BUG_ON(!hlist_empty(&vlan_group_hash[i]));
> 
>  	unregister_pernet_gen_device(vlan_net_id, &vlan_net_ops);
> -	synchronize_net();
> +	rcu_barrier(); /* Wait for completion of call_rcu()'s */
> 
>  	vlan_gvrp_uninit();
>  }
>