Re: [PATCH] (1/8) Eliminate brlock in psnap

[Zwane Mwaikambo]

On Tue, 11 Mar 2003, Stephen Hemminger wrote:

>  void unregister_snap_client(struct datalink_proto *proto)
>  {
> -	br_write_lock_bh(BR_NETPROTO_LOCK);
> +	static RCU_HEAD(snap_rcu);
>  
> -	list_del(&proto->node);
> -	kfree(proto);
> +	spin_lock_bh(&snap_lock);
> +	list_del_rcu(&proto->node);
> +	spin_unlock_bh(&snap_lock);
>  
> -	br_write_unlock_bh(BR_NETPROTO_LOCK);
> +	call_rcu(&snap_rcu, (void (*)(void *)) kfree, proto);
>  }

Do we need the spin_lock_bh around the list_del_rcu? But also How 
about. This way we don't change the previous characteristic of block till 
done unregistering

struct datalink_proto {
...
	struct completion registration;
};

void __unregister_snap_client(void *__proto)
{
	struct datalink_proto *proto = __proto;
	complete(&proto->registration);
}

unregister_snap_client(struct datalink_proto *proto)
{
	list_del_rcu(&proto->node);
	call_rcu(&snap_rcu, __unregister_snap_client, proto);
	wait_for_completion(&proto->registration);
	kfree(proto);
}