Subject: Re: [RFC(v2) net-next 01/13] ndisc: Refer/Update neigh->updated with write lock.

From: Cong Wang <[email-masked]>
Date: Wed, 16 Jan 2013 14:35:40 +0800

On 01/16/2013 12:44 AM, YOSHIFUJI Hideaki wrote:
> Signed-off-by: YOSHIFUJI Hideaki <[email-masked]>
> ---
>   net/ipv6/route.c |   12 ++++++++----
>   1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index 7c34c01..1341f68 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -499,22 +499,26 @@ static void rt6_probe(struct rt6_info *rt)
>   	 * to no more than one per minute.
>   	 */
>   	neigh = rt ? rt->n : NULL;
> -	if (!neigh || (neigh->nud_state & NUD_VALID))
> +	if (!neigh)
> +		return;
> +	write_lock_bh(&neigh->lock);
> +	if (neigh->nud_state & NUD_VALID) {
> +		write_unlock_bh(&neigh->lock);
>   		return;
> -	read_lock_bh(&neigh->lock);
> +	}
>   	if (!(neigh->nud_state & NUD_VALID) &&
>   	    time_after(jiffies, neigh->updated + rt->rt6i_idev->cnf.rtr_probe_interval)) {
>   		struct in6_addr mcaddr;
>   		struct in6_addr *target;
>   
>   		neigh->updated = jiffies;
> -		read_unlock_bh(&neigh->lock);
> +		write_unlock_bh(&neigh->lock);

This looks like a bug fix, which deserves a separated patch rather than
in this rt->n removal series.