netdev - Re: [PATCH net-next] bridge: multicast router list manipulation

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Message-ID: <20100428015114.GB12165@gondor.apana.org.au>
Date:	Wed, 28 Apr 2010 09:51:14 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Stephen Hemminger <shemminger@...tta.com>
Cc:	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH net-next] bridge: multicast router list manipulation

On Tue, Apr 27, 2010 at 10:13:11AM -0700, Stephen Hemminger wrote:
> I prefer that the hlist be only accessed through the hlist macro
> objects. Explicit twiddling of links (especially with RCU) exposes
> the code to future bugs.
> 
> Compile tested only.
> 
> Signed-off-by: Stephen Hemminger <shemminger@...tta.com>
> 
> 
> --- a/net/bridge/br_multicast.c	2010-04-27 09:54:02.180531924 -0700
> +++ b/net/bridge/br_multicast.c	2010-04-27 10:07:19.188688664 -0700
> @@ -1041,21 +1041,21 @@ static int br_ip6_multicast_mld2_report(
>  static void br_multicast_add_router(struct net_bridge *br,
>  				    struct net_bridge_port *port)
>  {
> -	struct hlist_node *p;
> -	struct hlist_node **h;
> +	struct net_bridge_port *p;
> +	struct hlist_node *n, *last = NULL;
>  
> -	for (h = &br->router_list.first;
> -	     (p = *h) &&
> -	     (unsigned long)container_of(p, struct net_bridge_port, rlist) >
> -	     (unsigned long)port;
> -	     h = &p->next)
> -		;
> -
> -	port->rlist.pprev = h;
> -	port->rlist.next = p;
> -	rcu_assign_pointer(*h, &port->rlist);
> -	if (p)
> -		p->pprev = &port->rlist.next;
> +	hlist_for_each_entry(p, n, &br->router_list, rlist) {
> +		if ((unsigned long) port >= (unsigned long) p) {
> +			hlist_add_before_rcu(n, &port->rlist);
> +			return;
> +		}
> +		last = n;
> +	}
> +
> +	if (last)
> +		hlist_add_after_rcu(last, &port->rlist);
> +	else
> +		hlist_add_head_rcu(&port->rlist, &br->router_list);
>  }

Thanks Stephen, this looks good to me too.
-- 
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