Re: [PATCH v5 6/9] selftests: livepatch: Adapt atomic replace tests to provides/obsoletes

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The 'replace' feature detection in test_modules/Makefile fails for out-of-tree (O=) kernel builds, breaking tests on older kernels.
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--- Patch [6]: [PATCH v5 6/9] selftests: livepatch: Adapt atomic replace tests to provides/obsoletes ---
commit e4d15e9f2792340ea543b405f9d074e729665c9b
Author: Yafang Shao <[email protected]>

selftests: livepatch: Adapt atomic replace tests to provides/obsoletes

The legacy "replace" field in struct klp_patch was replaced by the
provides/obsoletes mechanism. This commit adapts selftests to build and
run on both old and new kernels by detecting the presence of the
"replace" field.

> diff --git a/tools/testing/selftests/livepatch/test_modules/Makefile b/tools/testing/selftests/livepatch/test_modules/Makefile
> index a13d398585dcb..29c55df360467 100644
> --- a/tools/testing/selftests/livepatch/test_modules/Makefile
> +++ b/tools/testing/selftests/livepatch/test_modules/Makefile
> @@ -16,6 +16,16 @@ obj-m += test_klp_atomic_replace.o \
>  	test_klp_state3.o \
>  	test_klp_syscall.o
>  
> +# The legacy "replace" field was replaced by provides/obsoletes. When the
> +# kernel (KDIR) still supports "replace", pass KLP_HAS_REPLACE to the
> +# modules so that they can #ifdef the legacy "replace" code. Otherwise
> +# the modules are built with the provides/obsoletes based code (to be
> +# added later).
> +KLP_HAS_REPLACE := $(shell grep -q 'bool replace' $(KDIR)/include/linux/livepatch.h 2>/dev/null && echo y)

[Severity: Medium]
Will this grep fail for out-of-tree (O=...) kernel builds?

If $(KDIR) points to the build directory rather than the source directory,
$(KDIR)/include/linux/livepatch.h might not exist.

When tests are run, detect_replace_attr() will still correctly identify the
replace sysfs attribute on the running kernel and set HAS_REPLACE_ATTR=1.

However, since the module would be compiled without KLP_HAS_REPLACE, it lacks
the replace module parameter. When the test scripts attempt to load the module
with replace=1, insmod will fail, causing the test suite to abort.

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Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=6