netdev - Re: [PATCH v6 net-next 04/14] selftests/net: gro: add self-test for TCP CWR flag

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Message-ID: <92c77477-9945-49c2-90bd-6e05761e2a3e@redhat.com>
Date: Tue, 18 Nov 2025 13:14:13 +0100
From: Paolo Abeni <pabeni@...hat.com>
To: chia-yu.chang@...ia-bell-labs.com, edumazet@...gle.com, parav@...dia.com,
 linux-doc@...r.kernel.org, corbet@....net, horms@...nel.org,
 dsahern@...nel.org, kuniyu@...gle.com, bpf@...r.kernel.org,
 netdev@...r.kernel.org, dave.taht@...il.com, jhs@...atatu.com,
 kuba@...nel.org, stephen@...workplumber.org, xiyou.wangcong@...il.com,
 jiri@...nulli.us, davem@...emloft.net, andrew+netdev@...n.ch,
 donald.hunter@...il.com, ast@...erby.net, liuhangbin@...il.com,
 shuah@...nel.org, linux-kselftest@...r.kernel.org, ij@...nel.org,
 ncardwell@...gle.com, koen.de_schepper@...ia-bell-labs.com,
 g.white@...lelabs.com, ingemar.s.johansson@...csson.com,
 mirja.kuehlewind@...csson.com, cheshire@...le.com, rs.ietf@....at,
 Jason_Livingood@...cast.com, vidhi_goel@...le.com
Subject: Re: [PATCH v6 net-next 04/14] selftests/net: gro: add self-test for
 TCP CWR flag

On 11/14/25 8:13 AM, chia-yu.chang@...ia-bell-labs.com wrote:
> +/* send extra flags of the (NUM_PACKETS / 2) and (NUM_PACKETS / 2 - 1)
> + * pkts, not first and not last pkt
> + */
> +static void send_flags(int fd, struct sockaddr_ll *daddr, int psh, int syn,
> +		       int rst, int urg, int cwr)
> +{
> +	static char flag_buf[2][MAX_HDR_LEN + PAYLOAD_LEN];
> +	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
> +	int payload_len, pkt_size, i;
> +	struct tcphdr *tcph;
> +	int flag[2];
> +
> +	payload_len = PAYLOAD_LEN * (psh || cwr);
> +	pkt_size = total_hdr_len + payload_len;
> +	flag[0] = NUM_PACKETS / 2;
> +	flag[1] = NUM_PACKETS / 2 - 1;
> +
> +	// Create and configure packets with flags

Please use /* */ for comments.

Other than that:

Acked-by: Paolo Abeni <pabeni@...hat.com>

> +	for (i = 0; i < 2; i++) {
> +		if (flag[i] > 0) {
> +			create_packet(flag_buf[i], flag[i] * payload_len, 0,
> +				      payload_len, 0);
> +			tcph = (struct tcphdr *)(flag_buf[i] + tcp_offset);
> +			set_flags(tcph, payload_len, psh, syn, rst, urg, cwr);
> +		}
> +	}
>  
>  	for (i = 0; i < NUM_PACKETS + 1; i++) {
> -		if (i == flag) {
> -			write_packet(fd, flag_buf, pkt_size, daddr);
> +		if (i == flag[0]) {
> +			write_packet(fd, flag_buf[0], pkt_size, daddr);
> +			continue;
> +		} else if (i == flag[1] && cwr) {
> +			write_packet(fd, flag_buf[1], pkt_size, daddr);
>  			continue;
>  		}
>  		create_packet(buf, i * PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
> @@ -1020,16 +1045,19 @@ static void gro_sender(void)
>  		send_ack(txfd, &daddr);
>  		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
>  	} else if (strcmp(testname, "flags") == 0) {
> -		send_flags(txfd, &daddr, 1, 0, 0, 0);
> +		send_flags(txfd, &daddr, 1, 0, 0, 0, 0);
>  		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
>  
> -		send_flags(txfd, &daddr, 0, 1, 0, 0);
> +		send_flags(txfd, &daddr, 0, 1, 0, 0, 0);
>  		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
>  
> -		send_flags(txfd, &daddr, 0, 0, 1, 0);
> +		send_flags(txfd, &daddr, 0, 0, 1, 0, 0);
>  		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
>  
> -		send_flags(txfd, &daddr, 0, 0, 0, 1);
> +		send_flags(txfd, &daddr, 0, 0, 0, 1, 0);
> +		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
> +
> +		send_flags(txfd, &daddr, 0, 0, 0, 0, 1);
>  		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
>  	} else if (strcmp(testname, "tcp") == 0) {
>  		send_changed_checksum(txfd, &daddr);
> @@ -1163,6 +1191,12 @@ static void gro_receiver(void)
>  
>  		printf("urg flag ends coalescing: ");
>  		check_recv_pkts(rxfd, correct_payload, 3);
> +
> +		correct_payload[0] = PAYLOAD_LEN;
> +		correct_payload[1] = PAYLOAD_LEN * 2;
> +		correct_payload[2] = PAYLOAD_LEN * 2;
> +		printf("cwr flag ends coalescing: ");
> +		check_recv_pkts(rxfd, correct_payload, 3);
>  	} else if (strcmp(testname, "tcp") == 0) {
>  		correct_payload[0] = PAYLOAD_LEN;
>  		correct_payload[1] = PAYLOAD_LEN;