Re: [PATCH mptcp-next] Squash to "selftests: mptcp: add splice io mode"

[Geliang Tang <geliang@kernel.org>]

Hi Matt,

Thanks for this fix.

On Fri, 2026-01-30 at 11:17 +0100, Matthieu Baerts (NGI0) wrote:
> NIPA review assistant rightly spotted errors with splice() are
> simply...
> ignored! Technically, mptcp_connect.sh will check the integrity of
> the
> transfer, but still, that's clearly not a good practice!
> 
> The different possible errors are now caught, printed, and reported
> to
> the caller.
> 
> Link:
> https://netdev-ai.bots.linux.dev/ai-review.html?id=93466fc9-574b-45fc-996e-13a19a1490a9
> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>

Looks good to me!

Reviewed-by: Geliang Tang <geliang@kernel.org>

> ---
>  tools/testing/selftests/net/mptcp/mptcp_connect.c | 34
> +++++++++++++++++------
>  1 file changed, 25 insertions(+), 9 deletions(-)
> 
> diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.c
> b/tools/testing/selftests/net/mptcp/mptcp_connect.c
> index ff1a298d3469..34d8efe429a4 100644
> --- a/tools/testing/selftests/net/mptcp/mptcp_connect.c
> +++ b/tools/testing/selftests/net/mptcp/mptcp_connect.c
> @@ -937,24 +937,40 @@ static int do_splice(const int infd, const int
> outfd, const size_t len,
>  		     struct wstate *winfo)
>  {
>  	int pipefd[2];
> -	ssize_t bytes;
> +	ssize_t in_bytes, out_bytes;

This line is longer than the previous one; their positions could be
swapped.

-Geliang

>  	int err;
>  
>  	err = pipe(pipefd);
> -	if (err)
> -		return err;
> +	if (err) {
> +		perror("pipe");
> +		return 2;
> +	}
>  
> -	while ((bytes = splice(infd, NULL, pipefd[1], NULL,
> -			       len - winfo->total_len,
> -			       SPLICE_F_MOVE | SPLICE_F_MORE)) > 0)
> {
> -		splice(pipefd[0], NULL, outfd, NULL, bytes,
> -		       SPLICE_F_MOVE | SPLICE_F_MORE);
> +again:
> +	in_bytes = splice(infd, NULL, pipefd[1], NULL, len - winfo-
> >total_len,
> +			  SPLICE_F_MOVE | SPLICE_F_MORE);
> +	if (in_bytes < 0) {
> +		perror("splice in");
> +		err = 3;
> +	} else if (in_bytes > 0) {
> +		out_bytes = splice(pipefd[0], NULL, outfd, NULL,
> in_bytes,
> +				   SPLICE_F_MOVE | SPLICE_F_MORE);
> +		if (out_bytes < 0) {
> +			perror("splice out");
> +			err = 4;
> +		} else if (in_bytes != out_bytes) {
> +			fprintf(stderr, "Unexpected transfer: %zu vs
> %zu\n",
> +				in_bytes, out_bytes);
> +			err = 5;
> +		} else {
> +			goto again;
> +		}
>  	}
>  
>  	close(pipefd[0]);
>  	close(pipefd[1]);
>  
> -	return 0;
> +	return err;
>  }
>  
>  static int copyfd_io_splice(int infd, int peerfd, int outfd,
> unsigned int size,
> 
> ---
> base-commit: 7d56f2ba4d372e9660633de02a01236209c9df8f
> change-id: 20260130-mptcp-sft-no-ignore-splice-err-a35a97c217db
> 
> Best regards,