Re: [PATCH mptcp-next 2/2] selftests: mptcp: simult_flows: set EXIT trap earlier

[Matthieu Baerts <matttbe@kernel.org>]

Hi Gang,

On 24/07/2026 08:52, Gang Yan wrote:
> From: Gang Yan <yangang@kylinos.cn>
> 
> Set the EXIT trap for cleanup immediately after creating the temporary
> file variables, before the dd commands that fill them and the namespace
> init, to ensure cleanup runs on any failure or interruption during the
> early setup phase. If either dd fails (e.g. ENOSPC), the temp files
> already created are not cleaned up.

From what I see, if one of the 'dd' command fails, the errors are simply
ignored.

> Assisted-by: Codex: GLM-5.2
> Signed-off-by: Gang Yan <yangang@kylinos.cn>
> ---
>  tools/testing/selftests/net/mptcp/simult_flows.sh | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/tools/testing/selftests/net/mptcp/simult_flows.sh b/tools/testing/selftests/net/mptcp/simult_flows.sh
> index 3ea3d1efe32e..b40dea5f9b30 100755
> --- a/tools/testing/selftests/net/mptcp/simult_flows.sh
> +++ b/tools/testing/selftests/net/mptcp/simult_flows.sh
> @@ -62,13 +62,12 @@ setup()
>  	sout=$(mktemp)
>  	cout=$(mktemp)
>  	capout=$(mktemp)
> +	trap cleanup EXIT
>  	size=$((2 * 2048 * 4096))
>  
>  	dd if=/dev/zero of=$small bs=4096 count=20 >/dev/null 2>&1
>  	dd if=/dev/zero of=$large bs=4096 count=$((size / 4096)) >/dev/null 2>&1

This 'fix' is only interesting when the script is abort while one of the
dd command is in progress, to create files of 80k and 16M in RAM. I
guess this is very unlikely, no?

If you already managed to end-up in this situation by accident, OK to
accept the change, but the commit message needs to be updated.

If it is a potential fix for an unlikely situation with the selftests,
we probably don't need that.

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.