Re: [PATCH net-next] net: Add support for filtering neigh dump by device index

[Nikolay Aleksandrov <nikolay@cumulusnetworks.com>]

On 10/03/2015 08:25 PM, David Ahern wrote:
> Add support for filtering neighbor dumps by device by adding the
> NDA_IFINDEX attribute to the dump request. When set the kernel only
> sends neighbor entries for the given device.
> 
> Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
> ---
>  net/core/neighbour.c | 17 +++++++++++++++--
>  1 file changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/net/core/neighbour.c b/net/core/neighbour.c
> index 8c57fdf4d68e..f7786eaef613 100644
> --- a/net/core/neighbour.c
> +++ b/net/core/neighbour.c
> @@ -2249,6 +2249,14 @@ static bool neigh_master_filtered(struct net_device *dev, int master_idx)
>  	return false;
>  }
>  
> +static bool neigh_ifindex_filtered(struct net_device *dev, int filter_idx)
> +{
> +	if (filter_idx && dev->ifindex != filter_idx)
> +		return true;
> +
> +	return false;
> +}
> +
>  static int neigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
>  			    struct netlink_callback *cb)
>  {
> @@ -2259,16 +2267,19 @@ static int neigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
>  	int rc, h, s_h = cb->args[1];
>  	int idx, s_idx = idx = cb->args[2];
>  	struct neigh_hash_table *nht;
> -	int filter_master_idx = 0;
> +	int filter_master_idx = 0, filter_idx = 0;
>  	unsigned int flags = NLM_F_MULTI;
>  	int err;
>  
>  	err = nlmsg_parse(nlh, sizeof(struct ndmsg), tb, NDA_MAX, NULL);
>  	if (!err) {
> +		if (tb[NDA_IFINDEX])
> +			filter_idx = nla_get_u32(tb[NDA_IFINDEX]);
> +
>  		if (tb[NDA_MASTER])
>  			filter_master_idx = nla_get_u32(tb[NDA_MASTER]);
>  
> -		if (filter_master_idx)
> +		if (filter_idx | filter_master_idx)
|| ? :-)

>  			flags |= NLM_F_DUMP_FILTERED;
>  	}
>  
> @@ -2283,6 +2294,8 @@ static int neigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
>  		     n = rcu_dereference_bh(n->next)) {
>  			if (!net_eq(dev_net(n->dev), net))
>  				continue;
> +			if (neigh_ifindex_filtered(n->dev, filter_idx))
> +				continue;
>  			if (neigh_master_filtered(n->dev, filter_master_idx))
>  				continue;
>  			if (idx < s_idx)
>