Re: [LTP] [PATCH 1/2] testcases/lib: Fix tst_ns_* helpers

Li Wang
2025-01-17T12:33:55Z

On Fri, Jan 17, 2025 at 8:25 PM Cyril Hrubis <chrubis@suse.cz> wrote:

> Replaces SAFE_CLONE() with tst_clone() in the tst_ns_* helpers.
>
> The reason for the replacement is that SAFE_CLONE() uses
> TST_RETRY_FUNC() which calls tst_multiply_timeout(). The problem with
> that is that the tst_multiply_timeout() is a test library function that
> started to print TINFO messages recently and that we rely on parsing the
> output from the tst_ns_* helpers.
>
> The reason SAFE_CLONE() started to call TST_RETRY_FUNC() is that in the
> case that we create new namespaces with the clone call, we may end up
> creating them faster than kernel can clean them up which is described in:
>
> commit 7d882081a5613f44a12fc6b1c44267d4df0857a4
> Author: Petr Vorel <pvorel@suse.cz>
> Date: Mon Mar 28 22:46:43 2022 +0200
>
> lib: Retry safe_clone() on ENOSPC
>
> This combined with the newly introduced changes in the test library that
> check for kernel debugging options that may need to adjust default
> timeouts:
>
> commit 893ca0abe7e82851ff0e5d93c09b1098f2eff121
> Author: Li Wang <liwang@redhat.com>
> Date: Sun Dec 22 15:22:49 2024 +0800
>
> lib: multiply the timeout if detect slow kconfigs
>
> which adds tst_has_slow_kconfig() into the tst_multiply_timeout() causes
> the TINFO messages to be printed.
>
> The reason why we can safely replace the SAFE_CLONE() with tst_clone()
> here is that we are not creating new namspaces in the tst_ns_* helpers,
> but rather than that cloning a new process to be executed inside of the
> namespace, hence we do not need to retry on ENOSPC.
>
> Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
>

Reviewed-by: Li Wang <liwang@redhat.com>

Nice work!

--
Regards,
Li Wang