netdev - Re: [net-next PATCH v2 1/1] bring netlink interface to par with brctl show macs

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Date:	Mon, 26 May 2014 03:35:47 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	Jamal Hadi Salim <jhs@...atatu.com>
Cc:	davem@...emloft.net, netdev@...r.kernel.org,
	stephen@...workplumber.org, vyasevic@...hat.com,
	john.r.fastabend@...el.com, sfeldma@...ulusnetworks.com
Subject: Re: [net-next PATCH v2 1/1] bring netlink interface to par with
 brctl show macs

On Sun, 2014-05-25 at 09:15 -0400, Jamal Hadi Salim wrote:
> From: Jamal Hadi Salim <jhs@...atatu.com>
> 
> This patch allows something equivalent to
> "brctl showmacs <bridge device>" with iproute2
> syntax "bridge fdb show br <bridge device>"
> Filtering by bridge is done in the kernel.
> The current setup doesnt scale when you have many bridges each
> with large fdbs (preliminary fix with the kernel patch).
> 
> Signed-off-by: Jamal Hadi Salim <jhs@...atatu.com>
> ---
>  net/core/rtnetlink.c |   49 ++++++++++++++++++++++++++++++++++---------------
>  1 file changed, 34 insertions(+), 15 deletions(-)
> 
> diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> index f31268d..1ad4828 100644
> --- a/net/core/rtnetlink.c
> +++ b/net/core/rtnetlink.c
> @@ -2509,26 +2509,45 @@ static int rtnl_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb)
>  {
>  	int idx = 0;
>  	struct net *net = sock_net(skb->sk);
> +	const struct net_device_ops *ops;
>  	struct net_device *dev;
> +	struct ndmsg *ndm;
>  
> -	rcu_read_lock();
> -	for_each_netdev_rcu(net, dev) {
> -		if (dev->priv_flags & IFF_BRIDGE_PORT) {
> -			struct net_device *br_dev;
> -			const struct net_device_ops *ops;
> -
> -			br_dev = netdev_master_upper_dev_get(dev);
> -			ops = br_dev->netdev_ops;
> -			if (ops->ndo_fdb_dump)
> -				idx = ops->ndo_fdb_dump(skb, cb, dev, idx);
> +	ndm = nlmsg_data(cb->nlh);
> +	if (ndm->ndm_ifindex) {
> +		dev = __dev_get_by_index(net, ndm->ndm_ifindex);
> +		if (dev == NULL) {
> +			pr_info("PF_BRIDGE: RTM_GETNEIGH with unknown ifindex\n");

You left another debug message here.

> +			return -ENODEV;
>  		}
>  
> -		if (dev->netdev_ops->ndo_fdb_dump)
> -			idx = dev->netdev_ops->ndo_fdb_dump(skb, cb, dev, idx);
> -		else
> -			idx = ndo_dflt_fdb_dump(skb, cb, dev, idx);
> +		ops = dev->netdev_ops;
> +		if (ops->ndo_fdb_dump) {
> +			idx = ops->ndo_fdb_dump(skb, cb, dev, idx);
> +		} else {
> +			pr_info("PF_BRIDGE: RTM_GETNEIGH %s no dumper\n",
> +				dev->name);

And here.

> +			return -EINVAL;
> +		}
[...]

Why does this only call the device's own ndo_fdb_dump and not a
bridge-port's bridge's ndo_fdb_dump or ndo_dflt_fdb_dump?

Ben.

-- 
Ben Hutchings
Humans are not rational beings; they are rationalising beings.

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