Re: [PATCH v5 10/12] kunit: Add 'kunit_shutdown' option

From: Kees Cook <keescook@chromium.org>
To: Brendan Higgins <brendanhiggins@google.com>
Cc: jdike@addtoit.com, richard@nod.at,
	anton.ivanov@cambridgegreys.com, arnd@arndb.de,
	skhan@linuxfoundation.org, alan.maguire@oracle.com,
	yzaikin@google.com, davidgow@google.com,
	akpm@linux-foundation.org, rppt@linux.ibm.com,
	frowand.list@gmail.com, catalin.marinas@arm.com, will@kernel.org,
	monstr@monstr.eu, mpe@ellerman.id.au, benh@kernel.crashing.org,
	paulus@samba.org, chris@zankel.net, jcmvbkbc@gmail.com,
	gregkh@linuxfoundation.org, sboyd@kernel.org,
	logang@deltatee.com, mcgrof@kernel.org,
	linux-um@lists.infradead.org, linux-arch@vger.kernel.org,
	linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com,
	linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linuxppc-dev@lists.ozlabs.org, linux-xtensa@linux-xtensa.org
Subject: Re: [PATCH v5 10/12] kunit: Add 'kunit_shutdown' option
Date: Fri, 26 Jun 2020 14:40:32 -0700	[thread overview]
Message-ID: <202006261436.DEF4906A5@keescook> (raw)
In-Reply-To: <20200626210917.358969-11-brendanhiggins@google.com>

On Fri, Jun 26, 2020 at 02:09:15PM -0700, Brendan Higgins wrote:
> From: David Gow <davidgow@google.com>
> 
> Add a new kernel command-line option, 'kunit_shutdown', which allows the
> user to specify that the kernel poweroff, halt, or reboot after
> completing all KUnit tests; this is very handy for running KUnit tests
> on UML or a VM so that the UML/VM process exits cleanly immediately
> after running all tests without needing a special initramfs.
> 
> Signed-off-by: David Gow <davidgow@google.com>
> Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
> Reviewed-by: Stephen Boyd <sboyd@kernel.org>
> ---
>  lib/kunit/executor.c                | 20 ++++++++++++++++++++
>  tools/testing/kunit/kunit_kernel.py |  2 +-
>  tools/testing/kunit/kunit_parser.py |  2 +-
>  3 files changed, 22 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/kunit/executor.c b/lib/kunit/executor.c
> index a95742a4ece73..38061d456afb2 100644
> --- a/lib/kunit/executor.c
> +++ b/lib/kunit/executor.c
> @@ -1,5 +1,6 @@
>  // SPDX-License-Identifier: GPL-2.0
>  
> +#include <linux/reboot.h>
>  #include <kunit/test.h>
>  
>  /*
> @@ -11,6 +12,23 @@ extern struct kunit_suite * const * const __kunit_suites_end[];
>  
>  #if IS_BUILTIN(CONFIG_KUNIT)
>  
> +static char *kunit_shutdown;
> +core_param(kunit_shutdown, kunit_shutdown, charp, 0644);
> +
> +static void kunit_handle_shutdown(void)
> +{
> +	if (!kunit_shutdown)
> +		return;
> +
> +	if (!strcmp(kunit_shutdown, "poweroff"))
> +		kernel_power_off();
> +	else if (!strcmp(kunit_shutdown, "halt"))
> +		kernel_halt();
> +	else if (!strcmp(kunit_shutdown, "reboot"))
> +		kernel_restart(NULL);
> +
> +}

If you have patches that do something just before the initrd, and then
you add more patches to shut down immediately after an initrd, people
may ask you to just use an initrd instead of filling the kernel with
these changes...

I mean, I get it, but it's not hard to make an initrd that poke a sysctl
to start the tests...

In fact, you don't even need a initrd to poke sysctls these days.

-- 
Kees Cook