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

From: Stanislav Fomichev <[email-masked]>
Date: Mon, 4 Nov 2024 19:33:00 -0800

On 11/04, Jakub Kicinski wrote:
> 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? 🤔️

Are you having some extra -W arguments to make it trigger on the build
bot? Wonder why I don't see the warning locally.. (will try to pass
-Wformat-truncation)