[RESEND PATCH] s390: fix dead defaults for S390_MODULES_SANITY_TEST and S390_UNWIND_SELFTEST

[RESEND PATCH] s390: fix dead defaults for S390_MODULES_SANITY_TEST and S390_UNWIND_SELFTEST

[Julian Braha]

These config options currently have unconditional defaults of 'n' from the
def_tristate statement, which shadow the later default of
'KUNIT_ALL_TESTS', causing it to be dead code.

It looks to me like the commit 25d36a85c61b ("s390/test_unwind: convert to KUnit")
added the KUNIT_ALL_TESTS default to S390_UNWIND_SELFTEST, but mistakenly
didn't remove the previous 'n' default.

Then, the later commit 90c5318795ee ("s390/module: test loading modules with a lot of relocations")
copied the Kconfig layout from S390_UNWIND_SELFTEST when adding the
S390_MODULES_SANITY_TEST config option, without noticing the existing mistake.

This dead code was found by kconfirm, a static analysis tool for Kconfig.

Fixes: 25d36a85c61b ("s390/test_unwind: convert to KUnit")
Fixes: 90c5318795ee ("s390/module: test loading modules with a lot of relocations")
Signed-off-by: Julian Braha <julianbraha@gmail.com>
---
 arch/s390/Kconfig | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index edc927d9e85a..1b3afe89cb00 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -999,9 +999,8 @@ config S390_MODULES_SANITY_TEST_HELPERS
 menu "Selftests"
 
 config S390_UNWIND_SELFTEST
-	def_tristate n
+	def_tristate KUNIT_ALL_TESTS
 	depends on KUNIT
-	default KUNIT_ALL_TESTS
 	prompt "Test unwind functions"
 	help
 	  This option enables s390 specific stack unwinder testing kernel
@@ -1023,9 +1022,8 @@ config S390_KPROBES_SANITY_TEST
 	  Say N if you are unsure.
 
 config S390_MODULES_SANITY_TEST
-	def_tristate n
+	def_tristate KUNIT_ALL_TESTS
 	depends on KUNIT
-	default KUNIT_ALL_TESTS
 	prompt "Enable s390 specific modules tests"
 	select S390_MODULES_SANITY_TEST_HELPERS
 	help
-- 
2.53.0

Re: [RESEND PATCH] s390: fix dead defaults for S390_MODULES_SANITY_TEST and S390_UNWIND_SELFTEST

[Alexander Gordeev]

On Tue, Apr 14, 2026 at 10:56:51PM +0100, Julian Braha wrote:
> These config options currently have unconditional defaults of 'n' from the
> def_tristate statement, which shadow the later default of
> 'KUNIT_ALL_TESTS', causing it to be dead code.
> 
> It looks to me like the commit 25d36a85c61b ("s390/test_unwind: convert to KUnit")
> added the KUNIT_ALL_TESTS default to S390_UNWIND_SELFTEST, but mistakenly
> didn't remove the previous 'n' default.
> 
> Then, the later commit 90c5318795ee ("s390/module: test loading modules with a lot of relocations")
> copied the Kconfig layout from S390_UNWIND_SELFTEST when adding the
> S390_MODULES_SANITY_TEST config option, without noticing the existing mistake.
> 
> This dead code was found by kconfirm, a static analysis tool for Kconfig.

This tool is still in development, right?

Anyway, I do not quite get what do you mean with the dead code.
Could you please elaborate?

> Fixes: 25d36a85c61b ("s390/test_unwind: convert to KUnit")
> Fixes: 90c5318795ee ("s390/module: test loading modules with a lot of relocations")
> Signed-off-by: Julian Braha <julianbraha@gmail.com>
> ---
>  arch/s390/Kconfig | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)

Thanks!

Re: [RESEND PATCH] s390: fix dead defaults for S390_MODULES_SANITY_TEST and S390_UNWIND_SELFTEST

[Julian Braha]

On Wed, 29 Apr 2026, Alexander Gordeev <agordeev@linux.ibm.com> wrote:
> This tool is still in development, right?

You can find the latest release (v0.7) outside the tree here:
https://github.com/julianbraha/kconfirm

And there's also a recent RFC to move it into the tree here:
https://lore.kernel.org/all/20260427174429.779474-1-julianbraha@gmail.com/

> Anyway, I do not quite get what do you mean with the dead code.
> Could you please elaborate?

Sure! In kconfig, default statements are evaluated in the order
they appear (top --> bottom). This means that if you have an
unconditional default statement at the top, e.g. 'default n', then all
of the default statements that follow it will never be evaluated - in
other words, they are dead code.

In the case of this code in particular, the 'def_tristate n' at the top
does two things:
1. declares the type of the config option as a tristate,
2. sets the default value to 'n' unconditionally.

So, the 'default KUNIT_ALL_TESTS' statement that follows is dead code.

See also this sentence from the "Menu attributes" section of the kconfig
docs:
"If multiple default values are visible, only the first defined one is
active."
Source:
https://docs.kernel.org/kbuild/kconfig-language.html

- Julian Braha