Re: [PATCH net-next 2/5] net: hns3: support ndo_select_queue()

[Paolo Abeni <pabeni@redhat.com>]

On Mon, 2022-09-05 at 16:15 +0800, Guangbin Huang wrote:
> To support tx packets to select queue according to its dscp field after
> setting dscp and tc map relationship, this patch implements
> ndo_select_queue() to set skb->priority according to the user's setting
> dscp and priority map relationship.
> 
> Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
> ---
>  .../net/ethernet/hisilicon/hns3/hns3_enet.c   | 46 +++++++++++++++++++
>  1 file changed, 46 insertions(+)
> 
> diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
> index 481a300819ad..82f83e3f8162 100644
> --- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
> +++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
> @@ -2963,6 +2963,51 @@ static int hns3_nic_set_vf_mac(struct net_device *netdev, int vf_id, u8 *mac)
>  	return h->ae_algo->ops->set_vf_mac(h, vf_id, mac);
>  }
>  
> +#define HNS3_INVALID_DSCP		0xff
> +#define HNS3_DSCP_SHIFT			2
> +
> +static u8 hns3_get_skb_dscp(struct sk_buff *skb)
> +{
> +	__be16 protocol = skb->protocol;
> +	u8 dscp = HNS3_INVALID_DSCP;
> +
> +	if (protocol == htons(ETH_P_8021Q))
> +		protocol = vlan_get_protocol(skb);
> +
> +	if (protocol == htons(ETH_P_IP))
> +		dscp = ipv4_get_dsfield(ip_hdr(skb)) >> HNS3_DSCP_SHIFT;
> +	else if (protocol == htons(ETH_P_IPV6))
> +		dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> HNS3_DSCP_SHIFT;
> +
> +	return dscp;
> +}
> +
> +static u16 hns3_nic_select_queue(struct net_device *netdev,
> +				 struct sk_buff *skb,
> +				 struct net_device *sb_dev)
> +{
> +	struct hnae3_handle *h = hns3_get_handle(netdev);
> +	u8 dscp, priority;
> +	int ret;
> +
> +	if (h->kinfo.tc_map_mode != HNAE3_TC_MAP_MODE_DSCP ||
> +	    !h->ae_algo->ops->get_dscp_prio)
> +		goto out;
> +
> +	dscp = hns3_get_skb_dscp(skb);
> +	if (unlikely(dscp == HNS3_INVALID_DSCP))
> +		goto out;
> +
> +	ret = h->ae_algo->ops->get_dscp_prio(h, dscp, NULL, &priority);

This introduces an additional, unneeded indirect call in the fast path,
you could consider replacing the above with a direct call to
hclge_get_dscp_prio() - again taking care of the CONFIG_HNS3_DCB
dependency.

Cheers,

Paolo