Re: [PATCH v3 1/3] selftests: kselftest: avoid cd - in runner

[Hajime Tazaki <thehajime@gmail.com>]

On Tue, 29 Sep 2026 03:16:48 +0900,
Pedro Falcato wrote:
> 
> On Mon, Sep 28, 2026 at 06:27:42PM +0100, Pedro Falcato wrote:
> > On Sat, Sep 26, 2026 at 10:08:17AM +0900, Hajime Tazaki wrote:
> > > The kselftest runner currently uses `cd -` to restore its working
> > > directory after running a test.
> > > 
> > > This is not supported by the minimal BusyBox hush shell used by some
> > > NOMMU targets. Store the original directory explicitly and restore it
> > > with a quoted path instead.
> > > 
> > > This also avoids printing the directory change performed by `cd -` and
> > > handles paths containing whitespace correctly.
> > > 
> > > Cc: Shuah Khan <shuah@kernel.org>
> > > Cc: Kees Cook <kees@kernel.org>
> > > Cc: Andy Lutomirski <luto@amacapital.net>
> > > Cc: Will Drewry <wad@chromium.org>
> > > Cc: Mark Brown <broonie@kernel.org>
> > > Cc: Brendan Jackman <brendan.jackman@linux.dev>
> > > Cc: Hangbin Liu <liuhangbin@gmail.com>
> > > Cc: "Ricardo B. Marliere" <rbm@suse.com>
> > > Cc: linux-kselftest@vger.kernel.org
> > > Cc: linux-um@lists.infradead.org
> > > Cc: linux-mm@kvack.org
> > > Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
> > 
> > NACK.
> > 
> > https://pubs.opengroup.org/onlinepubs/009695099/utilities/cd.html
> > 
> > -
> > When a hyphen is used as the operand, this shall be equivalent to the command:
> > cd "$OLDPWD" && pwd
> > 
> > which changes to the previous working directory and then writes its name.
> > 
> > 
> > If you're running selftests on !POSIX compliant shells, that's a
> > you-issue. Fix the shell, or use something decent.
> 
> ... I realize I was a bit too aggressive but seriously, lets not support
> broken software, please?

thanks for the comments.

no, your comment makes 100% sense to me.
under fork-less environment, we have less options but I agree that
this should be addressed in a shell implementation.

I will try to fix a busybox shell and drop this patch from next spin.

-- Hajime