Re: [net-next PATCH v1 3/7] net: add fdb generic dump routine

[Ben Hutchings <bhutchings@solarflare.com>]

On Mon, 2012-04-09 at 15:00 -0700, John Fastabend wrote:
> This adds a generic dump routine drivers can call. It
> should be sufficient to handle any bridging model that
> uses the unicast address list. This should be most SR-IOV
> enabled NICs.
[...]
> +static int nlmsg_populate_fdb(struct sk_buff *skb,
> +			      struct netlink_callback *cb,
> +			      struct net_device *dev,
> +			      int *idx,
> +			      struct netdev_hw_addr_list *list)
> +{
> +	struct netdev_hw_addr *ha;
> +	struct ndmsg *ndm;
> +	struct nlmsghdr *nlh;
> +	u32 pid, seq;
> +
> +	pid = NETLINK_CB(cb->skb).pid;
> +	seq = cb->nlh->nlmsg_seq;
> +
> +	list_for_each_entry(ha, &list->list, list) {
> +		if (*idx < cb->args[0])
> +			goto skip;
> +
> +		nlh = nlmsg_put(skb, pid, seq,
> +				RTM_NEWNEIGH, sizeof(*ndm), NLM_F_MULTI);
> +		if (!nlh)
> +			break;

This break is effectively return 0, but shouldn't we return an error?
In practice this does no harm because any subsequent invocation of
nlmsg_populate_fdb() for the same skb is also going to fail here with no
change to *idx.  But it would be more obviously correct to return an
error.

[...]
> +	}
> +	return 0;
> +nla_put_failure:
> +	nlmsg_cancel(skb, nlh);
> +	return -ENOMEM;
> +}
[...]

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.