Re: [PATCH v3] Compiler Attributes: remove CONFIG_ENABLE_MUST_CHECK

On Sat, Nov 28, 2020 at 11:34 AM Masahiro Yamada masahiroy@kernel.org wrote:

Revert commit cebc04ba9aeb ("add CONFIG_ENABLE_MUST_CHECK").

A lot of warn_unused_result warnings existed in 2006, but until now they have been fixed thanks to people doing allmodconfig tests.

Our goal is to always enable __must_check where appropriate, so this CONFIG option is no longer needed.

I see a lot of defconfig (arch/*/configs/*_defconfig) files having:

# CONFIG_ENABLE_MUST_CHECK is not set

I did not touch them for now since it would be a big churn. If arch maintainers want to clean them up, please go ahead.

While I was here, I also moved __must_check to compiler_attributes.h from compiler_types.h

Signed-off-by: Masahiro Yamada masahiroy@kernel.org Acked-by: Jason A. Donenfeld Jason@zx2c4.com

Reviewed-by: Nick Desaulniers ndesaulniers@google.com

---

Changes in v3:

• Fix a typo

Changes in v2:

• Move __must_check to compiler_attributes.h

include/linux/compiler_attributes.h | 7 +++++++ include/linux/compiler_types.h | 6 ------ lib/Kconfig.debug | 8 -------- tools/testing/selftests/wireguard/qemu/debug.config | 1 - 4 files changed, 7 insertions(+), 15 deletions(-)

diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h index b2a3f4f641a7..5f3b7edad1a7 100644 --- a/include/linux/compiler_attributes.h +++ b/include/linux/compiler_attributes.h @@ -171,6 +171,13 @@ */ #define __mode(x) __attribute__((__mode__(x)))

+/*

• • gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-war...
• • clang: https://clang.llvm.org/docs/AttributeReference.html#nodiscard-warn-unused-re...
• */

+#define __must_check __attribute__((__warn_unused_result__))

/*

• Optional: only supported since gcc >= 7

diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index ac3fa37a84f9..7ef20d1a6c28 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -110,12 +110,6 @@ struct ftrace_likely_data { unsigned long constant; };

-#ifdef CONFIG_ENABLE_MUST_CHECK -#define __must_check __attribute__((__warn_unused_result__)) -#else -#define __must_check -#endif

#if defined(CC_USING_HOTPATCH) #define notrace __attribute__((hotpatch(0, 0))) #elif defined(CC_USING_PATCHABLE_FUNCTION_ENTRY) diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index c789b39ed527..cb8ef4fd0d02 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -286,14 +286,6 @@ config GDB_SCRIPTS

endif # DEBUG_INFO

-config ENABLE_MUST_CHECK

•   bool "Enable __must_check logic"
  

•   default y
  

•   help
  

•     Enable the __must_check logic in the kernel build.  Disable this to
  

•     suppress the "warning: ignoring return value of 'foo', declared with
  

•     attribute warn_unused_result" messages.
  

config FRAME_WARN int "Warn for stack frames larger than" range 0 8192 diff --git a/tools/testing/selftests/wireguard/qemu/debug.config b/tools/testing/selftests/wireguard/qemu/debug.config index b50c2085c1ac..fe07d97df9fa 100644 --- a/tools/testing/selftests/wireguard/qemu/debug.config +++ b/tools/testing/selftests/wireguard/qemu/debug.config @@ -1,5 +1,4 @@ CONFIG_LOCALVERSION="-debug" -CONFIG_ENABLE_MUST_CHECK=y CONFIG_FRAME_POINTER=y CONFIG_STACK_VALIDATION=y CONFIG_DEBUG_KERNEL=y -- 2.27.0