Subject: Re: [PATCH net-next v7 06/12] selftests: ncdevmem: Switch to AF_INET6

From: Jakub Kicinski <[email-masked]>
Date: Mon, 4 Nov 2024 17:54:18 -0800

On Mon,  4 Nov 2024 10:14:24 -0800 Stanislav Fomichev wrote:
> -static int configure_flow_steering(void)
> +static int configure_flow_steering(struct sockaddr_in6 *server_sin)
>  {
> -	return run_command("sudo ethtool -N %s flow-type tcp4 %s %s dst-ip %s %s %s dst-port %s queue %d >&2",
> +	const char *type = "tcp6";
> +	const char *server_addr;
> +	char buf[256];
> +
> +	inet_ntop(AF_INET6, &server_sin->sin6_addr, buf, sizeof(buf));
> +	server_addr = buf;
> +
> +	if (IN6_IS_ADDR_V4MAPPED(&server_sin->sin6_addr)) {
> +		type = "tcp4";
> +		server_addr = strrchr(server_addr, ':') + 1;
> +	}
> +
> +	return run_command("sudo ethtool -N %s flow-type %s %s %s dst-ip %s %s %s dst-port %s queue %d >&2",
>  			   ifname,
> +			   type,
>  			   client_ip ? "src-ip" : "",
>  			   client_ip ?: "",
> -			   server_ip,
> +			   server_addr,
>  			   client_ip ? "src-port" : "",
>  			   client_ip ? port : "",
>  			   port, start_queue);

nit: I think this generate a truncation warning, not sure if it's easy
to fix:

ncdevmem.c:259:28: warning: ‘%s’ directive output may be truncated writing up to 255 bytes into a region of size between 209 and 215 [-Wformat-truncation=]
  259 |         return run_command("sudo ethtool -N %s flow-type %s %s %s dst-ip %s %s %s dst-port %s queue %d >&2",
      |                            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

maybe make buf smaller? 🤔️