Re: [PATCH v7] net: optimize raw checksum computation

[Stephen Hemminger <stephen@networkplumber.org>]

On Thu,  8 Jan 2026 09:59:13 -0500
scott.k.mitch1@gmail.com wrote:

> diff --git a/lib/net/rte_ip4.h b/lib/net/rte_ip4.h
> index 822a660cfb..67033875cc 100644
> --- a/lib/net/rte_ip4.h
> +++ b/lib/net/rte_ip4.h
> @@ -223,21 +223,19 @@ rte_ipv4_phdr_cksum(const struct rte_ipv4_hdr *ipv4_hdr, uint64_t ol_flags)
>  		uint8_t  zero;     /* zero. */
>  		uint8_t  proto;    /* L4 protocol type. */
>  		uint16_t len;      /* L4 length. */
> -	} psd_hdr;
> -
> -	uint32_t l3_len;
> -
> -	psd_hdr.src_addr = ipv4_hdr->src_addr;
> -	psd_hdr.dst_addr = ipv4_hdr->dst_addr;
> -	psd_hdr.zero = 0;
> -	psd_hdr.proto = ipv4_hdr->next_proto_id;
> -	if (ol_flags & (RTE_MBUF_F_TX_TCP_SEG | RTE_MBUF_F_TX_UDP_SEG)) {
> -		psd_hdr.len = 0;
> -	} else {
> -		l3_len = rte_be_to_cpu_16(ipv4_hdr->total_length);
> -		psd_hdr.len = rte_cpu_to_be_16((uint16_t)(l3_len -
> -			rte_ipv4_hdr_len(ipv4_hdr)));
> -	}
> +	} psd_hdr = {
> +		.src_addr = ipv4_hdr->src_addr,
> +		.dst_addr = ipv4_hdr->dst_addr,
> +		.proto = ipv4_hdr->next_proto_id,
> +		.len = (ol_flags & (RTE_MBUF_F_TX_TCP_SEG | RTE_MBUF_F_TX_UDP_SEG)) ? 0 :
> +			rte_cpu_to_be_16((uint16_t)(rte_be_to_cpu_16(ipv4_hdr->total_length) -
> +				rte_ipv4_hdr_len(ipv4_hdr)))
> +	};
> +#ifdef RTE_

I find it hard to read complex expressions in initialiazers.
Much better as original if statement.
Sometimes you need a union to convince compiler of aliasing