Re: [PATCH 2/3] selftests: mptcp: Fix input fd lifecycle in reconnection loop

[Geliang Tang <geliang@kernel.org>]

cc mptcp only.

On Mon, 2025-01-13 at 16:52 +0800, Cong Liu wrote:
> When both cfg_input and cfg_sockopt_types.mptfo are set, the input
> file
> descriptor (fd_in) is opened before the reconnection loop but closed
> within the loop. However, when mptfo is enabled, the descriptor is
> not
> reopened in the loop, causing subsequent iterations to use an invalid
> file descriptor.
> 
> Move the file open operation into the loop to ensure fd_in is always
> valid when needed, regardless of mptfo setting.
> 
> Signed-off-by: Cong Liu <liucong2@kylinos.cn>
> ---
>  tools/testing/selftests/net/mptcp/mptcp_connect.c | 8 +-------
>  1 file changed, 1 insertion(+), 7 deletions(-)
> 
> diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.c
> b/tools/testing/selftests/net/mptcp/mptcp_connect.c
> index 31f4c5618569..4d4ea4627daa 100644
> --- a/tools/testing/selftests/net/mptcp/mptcp_connect.c
> +++ b/tools/testing/selftests/net/mptcp/mptcp_connect.c
> @@ -1247,12 +1247,6 @@ int main_loop(void)
>  	struct addrinfo *peer;
>  	struct wstate winfo;
>  
> -	if (cfg_input && cfg_sockopt_types.mptfo) {
> -		fd_in = open(cfg_input, O_RDONLY);
> -		if (fd_in < 0)
> -			xerror("can't open %s:%d", cfg_input,
> errno);
> -	}
> -
>  	memset(&winfo, 0, sizeof(winfo));
>  	fd = sock_connect_mptcp(cfg_host, cfg_port, cfg_sock_proto,
> &peer, fd_in, &winfo);

Is this 'fd_in' here valid if the previous 'fd_in = open(cfg_input,
O_RDONLY);' is deleted?

>  	if (fd < 0)
> @@ -1270,7 +1264,7 @@ int main_loop(void)
>  	if (cfg_cmsg_types.cmsg_enabled)
>  		apply_cmsg_types(fd, &cfg_cmsg_types);
>  
> -	if (cfg_input && !cfg_sockopt_types.mptfo) {
> +	if (cfg_input) {
>  		fd_in = open(cfg_input, O_RDONLY);
>  		if (fd_in < 0)
>  			xerror("can't open %s:%d", cfg_input,
> errno);