Re: [PATCH v3 12/18] net/r8169: implement Tx path

[Stephen Hemminger <stephen@networkplumber.org>]

On Wed, 23 Oct 2024 11:33:22 +0800
Howard Wang <howard_wang@realsil.com.cn> wrote:

> +static uint32_t
> +rtl8125_get_patch_pad_len(struct rte_mbuf *tx_pkt)
> +{
> +	uint16_t dest_port = 0;
> +	uint32_t pad_len = 0;
> +	int udp_hdr_len = 8;
> +	int trans_data_len, l4_offset;
> +
> +	if (!(tx_pkt->l4_len && (tx_pkt->data_len < 175)))
> +		goto no_padding;
> +
> +	l4_offset = tx_pkt->l2_len + tx_pkt->l3_len;
> +	trans_data_len = tx_pkt->data_len - l4_offset;
> +
> +	if (trans_data_len > 3 && trans_data_len < MIN_PATCH_LENGTH) {
> +		rte_memcpy(&dest_port, rte_pktmbuf_mtod(tx_pkt,
> +							struct rte_ether_hdr *) + l4_offset + 2, 2);
> +		dest_port = ntohs(dest_port);

A couple things here.
1. Use the function rte_pktmbuf_mtod_offset to pick up the header.
2. Don't use hard coded offset from that use a local pointer to the type
3. Don't hard code the size of uint16.
4. Don't use rte_memcpy() for trivially small fixed size objects.
5. Avoid useless initializations (like dest_port)
6. Don't hard code size of UDP header.