Re: [net-next PATCH v3 04/10] netdev-genl: Add netlink framework functions for queue

[Paolo Abeni <pabeni@redhat.com>]

On Tue, 2023-09-19 at 15:27 -0700, Amritha Nambiar wrote:
> Implement the netdev netlink framework functions for
> exposing queue information.
> 
> Signed-off-by: Amritha Nambiar <amritha.nambiar@intel.com>
> Reviewed-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
> ---
>  net/core/netdev-genl.c |  207 +++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 204 insertions(+), 3 deletions(-)
> 
> diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
> index 336c608e6a6b..ceb7d1722f7c 100644
> --- a/net/core/netdev-genl.c
> +++ b/net/core/netdev-genl.c
[...] 
>  int netdev_nl_queue_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
>  {
> -	return -EOPNOTSUPP;
> +	struct netdev_nl_dump_ctx *ctx = netdev_dump_ctx(cb);
> +	const struct genl_info *info = genl_info_dump(cb);
> +	struct net *net = sock_net(skb->sk);
> +	unsigned int rxq_idx = ctx->rxq_idx;
> +	unsigned int txq_idx = ctx->txq_idx;
> +	struct net_device *netdev;
> +	u32 ifindex = 0;
> +	int err = 0;
> +
> +	if (info->attrs[NETDEV_A_QUEUE_IFINDEX])
> +		ifindex = nla_get_u32(info->attrs[NETDEV_A_QUEUE_IFINDEX]);
> +
> +	rtnl_lock();
> +	if (ifindex) {
> +		netdev = __dev_get_by_index(net, ifindex);
> +		if (netdev)
> +			err = netdev_nl_queue_dump_one(netdev, skb, info,
> +						       &rxq_idx, &txq_idx);
> +		else
> +			err = -ENODEV;
> +	} else {
> +		for_each_netdev_dump(net, netdev, ctx->ifindex) {
> +			err = netdev_nl_queue_dump_one(netdev, skb, info,
> +						       &rxq_idx, &txq_idx);
> +
> +			if (err < 0)
> +				break;
> +			if (!err) {
> +				rxq_idx = 0;
> +				txq_idx = 0;

AFAICS, above 'err' can be either < 0 or == 0. The second test: '!err'
should be unneeded and is a bit confusing.

Cheers,

Paolo