Re: [mptcp-next v2 2/7] selftests: mptcp: refactor send_query parameters for code clarity

[Matthieu Baerts <matttbe@kernel.org>]

Hi Gang,

On 16/04/2025 10:59, Gang Yan wrote:
> This patch use 'inet_diag_req_v2' instead of 'token' as parameters of
> send_query, and construct the req in 'get_mptcpinfo'. This modification
> can enhance the enhancing clarity of the code, and prepare for the
> dump_subflow_info.
> 
> Co-developed-by: Geliang Tang <geliang@kernel.org>
> Signed-off-by: Geliang Tang <geliang@kernel.org>
> Signed-off-by: Gang Yan <yangang@kylinos.cn>
> ---
>  .../testing/selftests/net/mptcp/mptcp_diag.c  | 19 ++++++++++---------
>  1 file changed, 10 insertions(+), 9 deletions(-)
> 
> diff --git a/tools/testing/selftests/net/mptcp/mptcp_diag.c b/tools/testing/selftests/net/mptcp/mptcp_diag.c
> index ea7cb1128044..8a5b7745c58c 100644
> --- a/tools/testing/selftests/net/mptcp/mptcp_diag.c
> +++ b/tools/testing/selftests/net/mptcp/mptcp_diag.c
> @@ -62,7 +62,7 @@ static void die_usage(int r)
>  	exit(r);
>  }
>  
> -static void send_query(int fd, __u32 token)
> +static void send_query(int fd, struct inet_diag_req_v2 *r)
>  {
>  	struct sockaddr_nl nladdr = {
>  		.nl_family = AF_NETLINK
> @@ -76,19 +76,13 @@ static void send_query(int fd, __u32 token)
>  			.nlmsg_type = SOCK_DIAG_BY_FAMILY,
>  			.nlmsg_flags = NLM_F_REQUEST
>  		},
> -		.r = {
> -			.sdiag_family = AF_INET,
> -			/* Real proto is set via INET_DIAG_REQ_PROTOCOL */
> -			.sdiag_protocol = IPPROTO_TCP,
> -			.id.idiag_cookie[0] = token,
> -		}
> +		.r = *r
>  	};
>  	struct rtattr rta_proto;
>  	struct iovec iov[6];
>  	int iovlen = 1;
>  	__u32 proto;
>  
> -	req.r.idiag_ext |= (1 << (INET_DIAG_INFO - 1));
>  	proto = IPPROTO_MPTCP;
>  	rta_proto.rta_type = INET_DIAG_REQ_PROTOCOL;
>  	rta_proto.rta_len = RTA_LENGTH(sizeof(proto));
> @@ -229,13 +223,20 @@ static void recv_nlmsg(int fd)
>  
>  static void get_mptcpinfo(__u32 token)
>  {
> +	struct inet_diag_req_v2 r = {
> +		.sdiag_family           = AF_INET,
> +		/* Real proto is set via INET_DIAG_REQ_PROTOCOL */
> +		.sdiag_protocol         = IPPROTO_TCP,
> +		.id.idiag_cookie[0]     = token,
> +	};
>  	int fd;
>  
>  	fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_SOCK_DIAG);
>  	if (fd < 0)
>  		die_perror("Netlink socket");
>  
> -	send_query(fd, token);
> +	r.idiag_ext |= (1 << (INET_DIAG_INFO - 1));

Out of curiosity, why can you not set idiag_ext above, when 'r' is declared?

> +	send_query(fd, &r);
>  	recv_nlmsg(fd);
>  
>  	close(fd);

Cheers,
Matt
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