Re: [PATCH mptcp-net v2 2/5] selftests: mptcp: connect: catch IO errors on listen side

[Geliang Tang <geliang@kernel.org>]

On Fri, 2025-09-05 at 20:18 +0200, Matthieu Baerts (NGI0) wrote:
> IO errors were correctly printed to stderr, and propagated up to the
> main loop for the server side, but the returned value was ignored. As
> a
> consequence, the program for the listener side was no longer exiting
> with an error code in case of IO issues.
> 
> Because of that, some issues might not have been seen. But very
> likely,
> most issues either had an effect on the client side, or the file
> transfer was not the expected one, e.g. the connection got reset
> before
> the end. Still, it is better to fix this.
> 
> The main consequence of this issue is the error that was reported by
> the
> selftests: the received and sent files were different, and the MIB
> counters were not printed. Also, when such errors happened during the
> 'disconnect' tests, the program tried to continue until the timeout.
> 
> Now when an IO error is detected, the program exits directly with an
> error.
> 
> Fixes: 05be5e273c84 ("selftests: mptcp: add disconnect tests")
> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
> ---
>  tools/testing/selftests/net/mptcp/mptcp_connect.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.c
> b/tools/testing/selftests/net/mptcp/mptcp_connect.c
> index
> 4f07ac9fa207cb08a934582b98d688d0b9512f97..c1586a7286123a509495ac319fd
> 624b98f0bfd18 100644
> --- a/tools/testing/selftests/net/mptcp/mptcp_connect.c
> +++ b/tools/testing/selftests/net/mptcp/mptcp_connect.c
> @@ -1112,6 +1112,8 @@ int main_loop_s(int listensock)
>  	salen = sizeof(ss);
>  	remotesock = accept(listensock, (struct sockaddr *)&ss,
> &salen);
>  	if (remotesock >= 0) {
> +		int err;
> +
>  		maybe_close(listensock);
>  		check_sockaddr(pf, &ss, salen);
>  		check_getpeername(remotesock, &ss, salen);
> @@ -1125,7 +1127,9 @@ int main_loop_s(int listensock)
>  		SOCK_TEST_TCPULP(remotesock, 0);
>  
>  		memset(&winfo, 0, sizeof(winfo));
> -		copyfd_io(fd, remotesock, 1, true, &winfo);
> +		err = copyfd_io(fd, remotesock, 1, true, &winfo);
> +		if (err)
> +			return err;

The file descriptor (fd) should be closed before returning.

Thanks,
-Geliang

>  	} else {
>  		perror("accept");
>  		return 1;